United States 

Department of 

Agriculture 

Forest Service 

Pacific Southwest 

Research Station 

General Technical 

Report PSW-128 

Proceedings of the Symposium 

on Current Research on 

Wood-Destroying Organisms 

and Future Prospects for 

Protecting Wood in Use 

September 13, 1989, Bend, Oregon 
Haverty, Michael I.; Wilcox, W. Wayne, technical coordinators. 1991. Proceedings of the symposium on current 

research on wood-destroying organisms and future prospects for protecting wood in use; September 13, 1989; 

Bend, OR. Gen. Tech. Rep. PSW-128. Berkeley, CA: Pacific Southwest Research Station, Forest Service, U.S. 

Department of Agriculture; 65 p. 

In 1989 the Western International Forest Disease Work Conference and the Western Forest Insect Work Conference 

met jointly in Bend, Oregon, during the week of September 11-15, 1989. One of the 90-minute, concurrent workshops 

scheduled during this period was a discussion of the biology and present and future control strategies of wood-destroying 

organisms. This subject area has not traditionally been of concern to these two organizations, either as it might relate to 

protection of wood in use or to the degradation of wood in a forest environment. It was felt that many of the professionals 

attending the meeting would be interested in a discussion of current research in the general area of wood-destroying 

organisms and the future for protection of wood in service. To ensure sufficient participation by knowledgeable 

pathologists and entomologists, the technical coordinators organized a day-long technical session on wood-destroying 

organisms, which emphasized state-of-the-art and future research needs and control practices. The subjects presented 

included: research on wood decay by the USDA Forest Service, new developments in wood-deterioration research from 

the International Research Group on Wood Preservation, methods for nondestructive evaluation of infestations and 

infections of wood-destroying insects and decay in structures, role of termites in forest management in Australia, 

chemotaxonomy of termites, agonistic behavior of termites, tunneling behavior of subterranean termites, bait/toxicant 

strategies for control of subterranean termites, and training of the pest control industry to utilize the new technologies. 

Retrieval Terms; wood biodeterioration, decay mechanisms, fungi, biosystematics, nondestructive evaluation, 

acoustic emission, termites, Australian forests, cuticular hydrocarbons, agonistic behavior, semiochemicals, tunneling 

behavior, foraging behavior, termiticides, bait toxicants. 

Authors assumed full responsibility for the submission of camera-ready manuscripts. 

Views expressed in each paper are those of the authors and not necessarily those of the sponsoring organizations. 

Trade names and commercial enterprises mentioned are solely for information and do not imply endorsement by the 

sponsoring organizations. 

Technical Coordinators: 

MICHAEL I. HAVERTY is a supervisory research entomologist in the Station's Regeneration Insect Research 

Unit in Berkeley. W. WAYNE WILCOX is professor of forestry and wood pathologist in the Forest Products Laboratory, 

University of California at Berkeley. 

Publisher: 

Pacific Southwest Research Station 

P.O. Box 245, Berkeley, California 94701 

May 1991 
Proceedings of the Symposium on 

Current Research on Wood-Destroying 

Organisms and Future Prospects for 

Protecting Wood in Use 

September 13, 1989, Bend, Oregon 

Michael I. Haverty and W. Wayne Wilcox, technical coordinators 

CONTENTS 

In Brief ...............................................................................................................................................................iii 

Introduction ......................................................................................................................................................... v 

Current Research on Wood Decay in the USDA Forest Service ........................................................................ 1 

Harold H. Burdsall, Jr. 

New Developments in Wood-Destroying Organisms from the International Research

Group on Wood Preservation ....................................................................................................................... 4 

Elmer L. Schmidt 

Need for Nondestructive Evaluation (NDE) in the Detection of Decay in Structures ......................................... 7 

W. Wayne Wilcox 

Termites and Forest Management in Australia .................................................................................................. 10 

Don McG. Ewart 

Cuticular Hydrocarbons: Species and Population-Level Discrimination in Termites ....................................... 15

Michael I. Haverty, Marion Page, Barbara L. Thorne, and Pierre Escoubas 

An Assessment of the Potential Uses of Agonistic Behaviors in Termite Control ............................................ 24 

Barbara L. Thorne and Michael I. Haverty 

Factors Affecting the Tunneling Behavior of the Western Subterranean Termite, 

Reticulitermes hesperus Banks ................................................................................................................... 28 

James L. Smith and Michael K. Rust 

The Potential of Using Acoustical Emission to Detect Termites Within Wood ................................................ 34 

Vernard R. Lewis and Richard L. Lemaster 

Direct Colony Baiting of Termite Colonies: A Tool for Ecological Studies ..................................................... 38 

Don McG. Ewart 

Behavioral Ecology of Subterranean Termites and Implications for Control .................................................... 43

J. Kenneth Grace 

i 
CONTENTS 

Baiting Techniques for Control of Coptotermes Species Within Existing

Buildings in Australia ................................................................................................................................46 

J.R.J. French 

Population Suppression of Subterranean Termites by Slow-Acting Toxicants ..................................................51 

Nan-Yao Su and Rudolf H. Scheffrahn 

How Do We Advise the Pest Control Industry in the Post-Organochlorine Era? ..............................................58 

J.R.J. French 

Discussion ..........................................................................................................................................................63 

ii 
IN BRIEF.. 

Haverty, Michael I.; Wilcox, W. Wayne, technical coordinators. 

1991. Proceedings of the symposium on current research on wood-destroying organisms and future prospects for protecting wood in use; September 13, 1989; 

Bend, OR. Gen. Tech. Rep. PSW-128. Berkeley, CA: 

Pacific Southwest Research Station, Forest Service, U.S. 

Department of Agriculture; 65 p. 

Retrieval Terms: wood biodeterioration, decay mechanisms, 

fungi, biosystematics, nondestructive evaluation, acoustic emission, termites, Australian forests, cuticular hydrocarbons, agonistic behavior, semiochemicals, tunneling behavior, foraging 

behavior, termiticides, bait toxicants. 

The USDA Forest Service's research on decay fungi and 

decay caused by fungi is done mainly in two research work units 

at the Forest Products Laboratory in Madison, Wisconsin. One 

unit, the Center for Forest Mycology Research, performs biosystematic research on root-rot and products-rot fungi in the genera 

Armillaria, Phellinus, and Phlebia. This group also maintains 

the culture collection supporting research on decay fungi. A 

second unit, Biodeterioration Research, concentrates on studies 

of the basic mechanisms of wood decay. 

New developments in wood-destroying organisms and in 

wood protection from the 20th annual meeting (May 1989 at 

Lappeenranta, Finland) of the International Research Group on 

Wood Preservation are highlighted in the areas of biological 

control of fungi, dry rot, decay mechanisms and product problems, new techniques, insect problems and control, and developments in wood preservatives. 

Examples of the need for nondestructive evaluation and 

remote sensing technologies for evaluating early stages of decay 

are presented. The need is critical to develop methods of analyzing internal decay at the center of large wood members, and 

decay behind concealing coverings. Current technologies are 

reviewed and their inadequacies are discussed. Acoustic emission (AE) and acousto-ultrasonics appear to hold the greatest 

promise among existing technologies. 

Acoustic emission equipment was used to detect drywood 

termites, Incisitermes minor, in ponderosa pine blocks under 

laboratory conditions. Using a 60 kHz transducer, AE levels 

were recorded for 0, 5, 10, 15, and 20 termites per block. The 

association of AE and varying numbers of drywood termites best 

fit an exponential curve. These data suggest that the detection 

capabilities of AE increase with increasing numbers of termites. 

The implications of this finding to the potential use of AE in 

detecting termites under field conditions are discussed. 

Termites have long been regarded as major pests of Australian forests. Drawing together research on termite ecology and 

mammal conservation, the argument is presented that this perception is wrong: termites are a vital component of native forests 

and are quite necessary for the survival of many wildlife species. 

Hydrocarbons in the cuticle of insects are essential in 

protecting them from desiccation. The vast variety of hydrocarbons synthesized by insects and the apparent species-specificity 

of cuticular hydrocarbon mixtures make them excellent taxonomic characters for separating species within termite genera. 

Preliminary data suggest that cuticular hydrocarbons might be 

used to sort specimens and to search for morphological characters within the subterranean termite genus Reticulitermes. Cuticular hydrocarbon profiles enabled population-level discrimination of Coptotermes formosanus from different geographic 

locations. 

The potential use of termite-termite agonism in pest control 

is explored and evaluated. Intra- and interspecific encounters 

among termites from different colonies are known to result in 

aggressive or avoidance behaviors in a variety of species. Recent 

studies suggest, however, that intraspecific confrontations only 

rarely evoke aggressive responses in several economically important termite genera in the United States (Coptotermes, 

Reticulitermes, and Zootermopsis). Thus the most promising 

applied use of natural agonistic behaviors among termites appears to be in research on individual- and colony-recognition 

systems. Artificial manipulation of recognition and response 

cues might facilitate novel control methodologies based on 

masking or interfering with natural stimuli. Directions for future 

research are discussed. 

Laboratory studies were conducted to determine factors 

that affect the tunneling behavior of Reticulitermes hesperus. 

Soil particles between 0.84 and 2.36 mm in size prevented 

tunneling. Exposure to solid layers of calcium, magnesium, or 

zinc borate did not repel workers, but produced greater than 87 

percent mortality within 10 days. No tunneling occurred in soils 

treated with registered termiticides tested at concentrations 

above 50 ppm. Exposure to bifenthrin and cypermethrin deposits as low as 1 ppm immobilized termite workers and prevented 

them from tunneling. 

Termites failed to penetrate a layer of dead termites killed 

by earlier exposure to chlorpyrifos. Contact with termites killed 

with chlorpyrifos resulted in 96 percent mortality of the tunneling workers. Workers readily penetrated layers of termites 

freshly killed by freezing. 

At 15°C, the distance tunneled by acclimated termites was 

significantly greater than those of unacclimated termites. At 21-

32°C, the acclimation period did not affect the distance tunneled. 

Tunneling rates were significantly lower at 15°C than at 21, 27, 

or 32°C and were significantly greater at 27°C than at 21 or 32°C. 

The benefits of direct colony baiting of Coptotermes lacteus 

are described. Bait substrates enclosed in polyvinyl chloride 

tubes were applied in direct contact with the galleries of a termite 

mound. Attention of researchers is drawn to the potential of this 

method for studying and controlling species other than the 

mound-building Coptotermes lacteus. 

Studies of Reticulitermes flavipes colonies in Ontario, 

iii 
Canada, indicate that these colonies contain greater foraging 

populations and forage over larger territories than was previously thought. Results are consistent with those obtained elsewherewith Coptotermes formosanus and Heterotermes aureus. 

Implications for the development of baiting techniques for 

termite control are discussed, and several laboratory investigations of potential bait toxicants and insecticidal dusts are reviewed. Behavioral chemicals are also potentially useful in 

termite control, and bioassays with tree extractives indicate that 

semiochemicals affecting termite orientation offer an explanation for the observed pattern of R. flavipes infestations in street 

trees in Toronto. 

Baiting techniques have been developed over the years to 

control Coptotermes species, the most economically important 

termite group in Australia. Given the restrictions on organochlorines as termiticides in North America, research has focussed on 

baiting programs against Coptotermes as alternatives to the 

current control measures of drenching soil with pesticides or 

fumigation of entire structures. Details of the baiting proceiv 

dures, toxins used, and their suitability for use in eradicating 

Coptotermes infestations in existing buildings are described. 

Suggestions are offered for the direction in which future baiting 

techniques may prove productive. 

Historic background and the concept of slow-acting toxicants for population suppression of subterranean termites are 

reviewed. Information needed for development of bait-toxicants 

and studies needed to generate such information are summarized. 

Given the loss of organochlorines as termiticides in North 

America, and with the possibility of such restrictions occurring 

in the future in Australia and elsewhere, how are entomologists 

to advise the pest control industry in termite control? A brief 

historical review of pesticide bans and the relevance of these 

bans to the present termite control situation are discussed. 

Suggestions are offered for entomologists to pursue an integrated pest management approach to termite control based on 

sound ecological parameters and social priorities. 
PREFACE 

Early in 1989, one of us (MIH) suggested to the organizing 

committee of the joint meeting of the Western International 

Forest Disease Work Conference (WIFDWC) and the Western 

Forest Insect Work Conference (WFIWC) that they include 

wood-destroying organisms on the program. They accepted the 

idea and wanted the workshop to be interdisciplinary and comoderated by an entomologist and a pathologist. We then began 

to formulate an agenda and to develop a list of likely participants. 

This subject area was not traditionally of concern to these two 

organizations, either as it might relate to protection of wood in 

use or to the degradation of wood in a forest environment. In 

addition, the likely participants on the list do not often attend 

either of these annual meetings. 

We feared very few of the attendees would have much to 

contribute to this workshop because there are so few entomologists or pathologists in these organizations who conduct research on wood-destroying organisms. We did think, however, 

that many of the professionals attending this meeting would be 

interested in a discussion of current research in the general area 

of wood-destroying organisms and the future for protection of 

wood in service. 

To attract scientists currently involved in research on wooddestroying organisms, we convened (by invitation) a technical 

session held during the joint meeting of the WIFDWC and 

WFIWC. We arranged an agenda of 15- to 20-minute presentations, divided equally between entomology and pathology. 

Unfortunately, the American Wood-Preservers' Association 

held their annual meeting concurrent with the joint meeting of 

the WIFDWC and WFIWC. Thus many of the wood pathologists who might have otherwise attended and made presentations were already committed to another meeting. As a result, the 

number of presentations by entomologists was much greater 

than those by pathologists. On the afternoon of September 14, 

we held a 90-minute workshop to summarize the presentations 

and discuss future direction of research on wood-destroying 

organisms. 

Michael I. Haverty W. Wayne Wilcox 

Technical Coordinator Technical Coordinator 

Pacific Southwest Forest Products Laboratory 

Research Station 

USDA Forest Service University of California 

Berkeley, California Berkeley, California 

v 
Current Research on Wood Decay in the USDA Forest Service1

Harold H. Burdsall, Jr.2 

Abstract: The Forest Service's research on decay fungi and 

decay caused by fungi is done mainly in two research work units 

at the Forest Products Laboratory. One unit, the Center for 

Forest Mycology Research, performs biosystematic research on 

root-rot and products-rot fungi in the genera Armillaria, Phellinus, 

and Phlebia and maintains the culture collection supporting this 

research and other research on decay fungi. A second unit, 

Biodeterioration Research, concentrates on studying the basic 

mechanism of wood decay. 

Most of the Forest Service's work on wood decay is being 

done in two work units in Forest Insect and Disease Research 

(FIDR) housed at the Forest Products Laboratory (FPL) in 

Madison, Wis. Work on wood preservation and biotechnological applications of wood decay fungi are also in progress at 

the FPL in Forest Products and Harvesting Research units, but 

the research on the decay fungi and biodeterioration is located in 

the FIDR units, the Center for Forest Mycology Research 

(CFMR) and Biodeterioration Research. 

CENTER FOR FOREST MYCOLOGY RESEARCH 

The investigations of the Center for Forest Mycology 

Research (CFMR) (Research Work Unit FPL 4501) mainly 

address the biosystematics of wood decay fungi and the maintenance of the Forest Service's culture collection of wood-rotting 

fungi. The problems under investigation by the scientists include the biosystematics and species delimitation in the genus 

Armillaria (the root- and butt-rot fungus), the taxonomy of the 

genus Phellinus (which causes substantial root and heart rots of 

forest trees), and the biosystematics of the genus Phlebia, 

(which, although it occurs mainly as a slash-rotting organism, is 

also found in products). In addition, several members of the 

genus Phlebia are of possible use in biopulping or other biotechnological endeavors. The other problem area under investigation in the CFMR involves the resolution of species complexes that are found within the culture collection. 

Biosystematics and Species Delimitation in Armillaria 

The work on the genus Armillaria has involved several 

approaches. One of the main approaches is the use of a rather 

1

 Presented at the Symposium on Current Research on Wood-Destroying 

Organisms and Future Prospects for Protecting Wood in Use, September 13, 

1989, Bend, Oregon. 2 Project Leader, Center for Forest Mycology Research, Forest Products 

Laboratory, Forest Service, U.S. Department of Agriculture, Madison, Wisconsin. 

unique serological technique to distinguish species of Armillaria. 

Instead of being inoculated into mice, goats or rabbits, the 

antigen (Almillaria fungal tissue) is inoculated into both sides of 

the breast and both legs of laying hens. After a second inoculation a week later, and a wait of 2 weeks for incubation within the 

chicken, the antibodies are at sufficient titer and deposited in the 

yolk of the eggs. The eggs are collected, the antibodies isolated, 

and the ELISA technique used to distinguish species on the 

basis of optical density of the color reaction. Our results to date 

indicate that we can distinguish several of the species readily. 

We will be putting more species into the system to see how 

widely applicable this technique might be, because now the 

system shows a great deal of promise. Using laying hens for 

antibody development is advantageous because of the ease of 

inoculation, the ease of obtaining the antibody material through 

the collection of eggs, the rapid increase of titer, and the apparent 

greater specificity (that is, less cross reactivity) of the antibodies 

developed in the egg yolk vs. the blood of the other animals. 

Other investigations on Armillaria are also in progress, 

including attempts to elucidate the nuclear cycle within the life 

cycle of the fungus. Attempts are also being made to develop a 

method for consistent fruiting of the various Armillaria species 

so that genetic material will be regularly available for research 

on the Armillaria species. Refinement of the mating compatibility system and development of methods for cultural identifications are both under study. 

Taxonomy of Phellinus 

Research on the genus Phellinus has resulted in a published 

synopsis of the species of the genus Phellinus in the world. It is 

complete with keys and descriptions—many taken from the 

literature, but otherwise not available. Work is also progressing 

on the delimitation of Phellinus species especially as it concerns 

the variability within species. Phellinus tremulae (Bond.) Bond. 

et Boriss. has been collected and isolates made from all across 

North America, and the variability within this species is being 

studied. The genetic compatibility within the species and other 

variations, both morphological and biological, are being examined. Other species complexes in this group are being examined 

as well. 

Biosystematics of Phlebia 

Research on the genus Phlebia is taking a number of 

different routes: morphological, genetic, and molecular-biological. The genus fruits well in culture so that single-spore 

isolates for incompatibility studies are easily available. Morphological studies are combined with these incompatibility studies 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 1 
and cultural studies to aid in distinguishing the species. In 

addition, the utility of restriction fragment length polymorphisms and gene sequencing is being appraised. This should 

give an idea about the reliability of this methodology/technology to the wood-rotting basidiomycetes and give support to the 

other types of taxonomic investigations that are proceeding. 

To date, the Phlebia rufa complex has been examined and 

found to consist of two different species. This information was 

supported by morphological and genetic data as well. Other 

species of this group are now under investigation. The results 

will not only give us a better idea of the taxonomy and identity 

of the various Phlebia species, but will also indicate the relationships among genera which are closely related to Phlebia. 

Resolution of Species Complexes 

We also have a program that is aimed at resolving species 

complexes in the culture collection. In cases in which we have 

numerous isolates of the same species and it is obvious that there 

are some misidentifications, these misidentifications are being 

resolved by finding the isolates that are similar in culture and 

then going to the fruiting body and finding the differences there 

as well. Two of the genera under investigation are Bjerkandera 

and Phellinus. A number of species that were previously put into 

genus Poria are also under investigation. 

BIODETERIORATION AND PRESERVATION OF WOOD 

Research Work Unit FPL 4551, Biodeterioration of Wood, 

is determining basic mechanisms involved in the decay process. 

The purpose of this work is to find the "Achilles heel" in the 

decay process that could guide the development of new or 

improved treatment. One approach is to use serological techniques including monoclonal antibody methodology to determine how the enzymes get into the wood. These studies use 

monoclonal antibodies to locate and characterize the enzymes 

responsible for wood decay. The presence of the enzymes in the 

sheath surrounding the hyphae and the delivery system transporting the enzymes into the wood are being studied. In addition, 

a technique for visualizing the delivery system of the enzymes 

into the wood substrates has been developed using the Scanning 

Electron Microscope. Results of this work indicate that the 

fungus does develop a sheath as has been suggested in other 

work. This sheath forms microfibrils and microfibrillar materials that penetrate the woody tissues and deliver the enzymes 

deep into the wood. The concept of the enzymes merely being 

distributed at random by diffusion is now regarded as improbable. This work is still in progress but may well provide information that will explain exactly how the enzymes are delivered to 

the woody substrate. 

Considerable progress has been made in understanding the 

nature of the cellulose-degrading agent produced by brown-rot 

fungi. The physical and chemical properties of brown-rotted 

cellulose have been elucidated, and electron spin resonance 

(ESR) has been used to identify formation of hydroxyl radical 

and paramagnetic metals. These results demonstrate that brownrot fungi depolymerize cellulose by oxidative cleavage. Because 

of the rapidity of the degradation, oxidative cleavage most likely 

takes place by formation of cellulose-metal ion complexes and 

reaction with oxygen radicals. Understanding the biochemistry 

of this system should provide tremendous opportunities to 

thwart decomposition of wood. 

Other work is aimed at the use of innocuous fungi as 

biocontrol agents against mold, stain and decay fungi. Species of 

Trichoderma and Scytalidium are the most promising. Methods 

of applying the control agent and the most effective species and 

strains to use are still being evaluated. Field tests to date have 

provided mixed results. 

Determining in a nondestructive manner that decay is 

present at an early stage involves the use of electron spin 

resonance. This technique is based on the idea that as decay 

progresses the element magnesium changes states. By using 

ESR the change in valence of the magnesium can be sensed, and 

the amount of decay can be determined at early stages. This work 

is still in progress. 

From the standpoint of control, the regulation of key enzymes in digestion and growth is of interest. Important digestive 

enzymes are those decomposing cellulose, hemicellulose, and 

lignin. For growth, enzymes of importance are those involved 

in nitrogen metabolism, such as glutamine synthetase and polyamine enzymes, and those involved in cell wall formation, such 

as chitin synthetase. 

Almost nothing is known about nitrogen metabolism in 

wood decay fungi, but it plays the most important role of the 

nonstructural nutrients in wood. The very low amounts of 

nitrogen in wood indicate that wood decay fungi have a very 

efficient mechanism for metabolizing and reusing nitrogen. 

Polyamines are nitrogen compounds found in fungi that are 

essential for growth and development. The biosynthesis of 

polyamines in most organisms can proceed through one of two 

metabolic pathways. However, only one pathway has been 

reported to be the route of synthesis in fungi. This feature makes 

the pathway an ideal target for specific regulation of polyamine 

production in wood decay fungi. The result would be the specific 

control of decay by affecting only fungal growth and development. We are using "suicide" inhibitors such as difluoromethylomithine (DFMO) in the study of polyamine transport systems 

and determining reaction steps in metabolic pathways. The 

inhibitors are enzyme specific and irreversible, acting at the 

catalytic site of the enzyme, which results in "suicide." These 

inhibitors are ideal candidates for studies to target the "Achilles 

heel" of the decay fungi. 

Another approach that might be utilized for specific inhibition of fungal growth and development is the use of chemicals 

that prevent synthesis of chitin, which is an essential component 

of fungal cell walls. Vertebrates do not possess chitinous tissue. 

This basic biological difference has stimulated interest in the 

development of pesticides that specifically inhibit chitin synthesis and have little or no effect on non-target organisms. We are 

presently studying inhibition of chitin synthetase from various 

fungi with chitin synthetase inhibitors. 

To digest the cell wall constituents of wood, enzymes must 

be released external to the fungus. Thus, one method of prevent2 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
ing fungal attack of wood would be to inactivate the extracellular 

degrading enzymes in situ or prevent their release from fungal 

hyphae. Extracellular enzymes, however, appear quite stable―

higher concentrations of chemical are often required to inactivate the enzyme than to prevent growth. A more promising 

approach, therefore, would be to find means to interfere with 

processes involved in enzyme secretion. 

Tunicamyacin and calmodulin antagonists are compounds 

that we found to inhibit secretion of carbohydrate-degrading 

enzymes by wood decay fungi. Tunicamyacin interferes with 

glycosylation or sugar attachment to enzymes, and calmodulin 

antagonists interfere with calcium transport, which appears to be 

a part of the secretory process. We do not propose to use these 

materials as wood preservatives, but they may serve as model 

systems in the continuing search for more environmentally 

compatible fungicides. 

Monitoring of the decay tests in both the deep South and 

other areas of the country is continuing, to learn about the 

effectiveness of various preservative treatments in preventing 

decay and stopping internal decay. 

REFERENCES 

Banik, Mark T.; Larsen, Michael J.; Burdsall, Harold H., Jr. 1990. The formation 

of clamp connections between compatible basidiospore germlings of species 

of Armillaria. Mycological Society of America Newsletter 41(1): 4. (abstr) 

Burdsall, Harold H., Jr. 1990. Taxonomic mycology: concerns about the present; 

optimism for the Future. Mycologia 82(1): 1-8 

Burdsall, Harold H., Jr.; Banik, Mark T. 1990. Cultural characteristics of the 

North American species of Armillaria in culture. Mycological Society of 

America Newsletter 41(l): 8. (abstr) 

Darmono, T.W.; Burdsall, Harold H., Jr. 1990. A method for identifying mating 

types of single spore isolates in Armillaria mellea. Mycological Society of 

America Newsletter 41(1): 13. (abstr) 

Darmono, T.W.; Burdsall, Harold H., Jr. 1990. Evidence of the dikaryotic cells 

of the stipe tissue of it Armillaria tabescens. Mycol. Soc. Amer. Newletter 

41(1): 13.(abstr) 

Highley, Terry L. 1989. Antagonism of Scytalidium lignicola against wood 

decay fungi. Doc. No. IGR/WP/1392. Stockholm: The International Research Group on Wood Preservation. Working group Ia Biological Problems 

(Flora); 14 p. 

Highley, Terry L. 1989. Wood decay: New concepts and opportunities for 

control. In: Proc., 85th annual meeting, American Wood-Preservers' Assoc.; 

1989 April 23-26; San Francisco, CA. Stevensville, MO: American WoodPreservers' Assoc. Vol. 85: 71-77. 

Highley, Terry L.; Micales, Jessie A. 1989. Effect of aromatic monomers on 

production of carbohydrate-degrading enzymes by white-rot and brown-rot 

fungi. FEMS Microbiology Letters 66: 15-22. 

Highley, Terry L. 1989. Influence of Calmodulin antagonists on production of 

carbohydrate-degrading enzymes of brown- and white-rot fungi. Material 

and Organismen 24(4): 241-250 

Highley, Terry L.; Kirk, T. Kent; Ibach, R. 1989. Effect of brown-rot fungi on 

celluose.[sic] In: O'Rear, Charles E.; Llewellyn, Gerald C., eds. Biodeterioration 

research 2- General biodeterioration, degradation, mycotoxins, biotoxins, 

and wood decay: Proceedings, 2d meeting, Pan American Biodeterioration 

Society, 1989 July 28-31; Washington, DC. New York: Plenum Press; 511-

525. 

Illman, Barbara L.; Highley, Terry L. 1989. Decomposition of wood by brownrot fungi. Biodeterioration Research 2: 465-484. 

Illman, Barbara L.; Meinholtz, Dore C.; Highley, Terry L. 1989. Manganese as 

a probe of fungal degradation of wood. In: O'Rear, Charles E.; Llewellyn, 

Gerald C., eds. Biodeterioration research 2- General biodeterioration, degradation, mycotoxins, biotoxins, and wood decay: Proceedings, 2d meeting, 

Pan American Biodeterioration Society; 1989 July 28-31; Washington, DC. 

New York: Plenum Press: 485-496. 

Johnson, Bruce R.; Gutzmer, David I. 1990. Comparison of preservative 

treatments in marine exposure of small wood panels. Res. Note FPL-RN0258. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest 

Products Laboratory; 28 p. 

Larsen, Michael J.; Cobb-Poulle, Leigh Ann. 1990. Phellinus 

(Hymenochaetaceae): A survey of the world taxa. Synopsis Fungorum 3: 

1-206. 

Larsen, Michael J. 1990. Reexamination of the nomenclatural types of Polyporus 

rimosus Berk. and P. badius Berk. Mycotaxon 37: 353-361. 

Lombard, Frances F. 1990. A cultural study of several species of Antrodia 

(Polyporaceae, Aphyllophorales.) Mycologia 82(2): 185-191. 

Micales, Jessie A.; Richter, Adrian L.; Highley, Terry L. 1989. Extracellular 

glucan production by Postia (= Poria) placenta. Material and Organismen 

24(4): 259-269. 

Nakasone, Karen K.; Sytsma, Kenneth J. 1989. Restriction-site mapping of 

mitochondria) DNA in Phlebia radata and Phlebia rufa: intraspecific and 

interspecific variation. Mycological Society of America Newsletter 40(1): 

40. (abstr) 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 3 
New Developments in Wood-Destroying Organisms from the 

International Research Group on Wood Preservation (IRG)1 

Elmer L. Schmidt2 

Abstract: New developments in 

wood-destroying organisms and in wood 

protection from the 20th annual meeting (May 

1989 at Lappeenranta, Finland) of the 

International Research Group on Wood 

Preservation (IRG) are highlighted in the 

areas of biological control of fungi, dry 

rot, decay mechanisms and product problems, 

new techniques, insect problems and control, 

and developments in wood preservatives. 

The aim of the International Research 

Group on Wood Preservation (IRG) is "to 

promote research throughout the world on the 

subject of wood preservation" (Anonymous 

1988). With members in 55 nations around the 

world, its annual meetings and the documents 

presented provide a stimulating forum for 

exchange and discussion of new ideas in 

research and problem-solving in the areas of 

wood-destroying organisms and methods of wood 

protection. 

The IRG Secretariat is currently housed 

in Sweden (Drottning Kristinas vag 47C, S-114 

28, Stockholm). The presentations at the 

annual meeting were organized into four main 

Working Groups with a number of Subgroups in 

each: 

Working Groups IA & IB--Flora and Fauna 

Microbial breakdown mechanisms 

The problem of pretreatment decay

The problem of dry rot

ermite behavior associated with new methods

of termite control 

Insects in dry wood (excluding termites) 

1Presented at the Symposium on Current 

Research on Wood-Destroying Organisms and 

Future Prospects for Protecting Wood in Use, 

September 13, 1989, Bend, Oregon. 

2Associate Professor, Department of 

Forest Products, University of Minnesota, 

2004 Folwell Ave., St. Paul, Minnesota 55108. 

Working Group II--Fundamentals of Testing 

Soft rot tests 

Field tests out of ground

contact Accelerated aging

tests 

Non-destructive testing for defects in wood 

structures 

Working Group III--Preservatives and Methods 

of Treatment 

Collaborative field experiment 

Health and safety aspects 

Remedial treatments 

Refractory timbers 

Working Group IV--Marine Wood Preservation 

Leaching of some copper-based preservatives 

The use of wood in boats 

Sheathing materials 

Given the great number of research 

documents (>125) discussed at the meeting, it 

was necessary to only skim the bulk of 

information for topics of interest to those 

attending the joint Western International 

Forest Disease Work Conference and Western 

Forest Insect Work Conference meeting. For 

more details and data on, the topics briefly 

discussed, please contact the IRG Secretariat 

for copies of specific documents. 

BIOLOGICAL CONTROL DEVELOPMENTS 

Control of blue stain on Araucaria 

cunninghamii Aiton in Australia with the 

bacterium Pseudomonas cepacia (ex Burkholder) 

Palleroni and Holmes was excellent in the 

laboratory, but only 50-65 percent effective 

in 2-month field trials (Benko 1989). Wood 

from a Scots pine pole treated 7 years 

earlier with Trichoderma spp. still resisted 

decay by Lentinus lepideus Fries in 

soil-block tests (Bruce and others 1989). 

4 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
NEW INFORMATION ON THE DRY ROT FUNGUS Serpula 

lacrymans (Wulfen ex Fries) Schroeter 

Dry rot fungus is a major destroyer of 

buildings in Europe and in certain areas of 

Japan and Australia. Mortar or some source of 

calcium seems necessary for growth to 

neutralize the copious oxalic acid produced 

by this fungus by the formation of calcium 

oxalate (Bech-Andersen 1989, Trong 1989). A 

heat treatment has been developed to 

eradicate the fungus from structures (40oC 

for 24 h), and fungus cell viability can be 

checked by Janus Green B stain (a method more 

sensitive than culture attempts) (Koch and 

others 1989). This fungus can remove nitrogen 

from the soil to enhance growth in wood (Doi 

and Togashi 1989). Temperature apparently 

restricts its distribution in Australia and 

its growth rate is not related to decay 

capacity (Thornton 1989a, b). 

MISCELLANEOUS POINTS ON WOOD DECAY 

Peniophora gigantea (Fries) Massee was 

found to be the most common decay fungus in 

Scots pine logs during air seasoning in the 

United Kingdom, and may well be so because of 

its use as a biological control agent against 

Heterobasidion annosum (Fries) Brefeld in the 

region of tree harvest (Zahora and Dickinson 

1989). Soft rot (not detectable by hammer 

sounding) appears not to be a problem in CCAtreated pine poles in Sweden where earlier 

treatments lacking copper failed in service 

(Friis-Hansen and Ludstrom 1989). 

Interesting work on the role of extracellular 

matrix in decay was presented by workers from 

the USDA Forest Products Laboratory in 

Madison, Wisconsin (Green and others 1989; 

Micales and others 1989), and work from 

Sweden has shown localization of lignin 

degrading enzymes in wood (Daniel and others 

1989). Work from South Africa has 

demonstrated that strictly anerobic fungi 

(from ruminates) can colonize and may degrade 

wood (Wiederhold and others 1989). New 

methods for detection of organisms include 

use of fluorescein diacetate (FDA) hydrolysis 

to measure mold growth on wood indirectly 

(Bjurman 1989), and ion mobility spectrometry 

(IMS) to detect bacterially infested red oak 

in the field (Lawrence and others 1989). 

INSECTS 

A review of toxicants used around the 

world to control termites was presented 

(French and LaFage 1989), and an excellent 

review on nonchemical termite barriers noted 

promise for small particle applications 

(French 1989). Chlordane residues in soil 

around homes in Louisiana reflect the fact 

that 14 percent of the treatment sites may be 

potentially susceptible to the Formosan 

termite (LaFage and Delaplane 1989). Early 

promise was demonstrated in the use of 

acoustic emissions to detect termites feeding 

in wood (Fujii and others 1989). Problems 

with weevils (Curculionidae) and death watch 

beetles (Anobiidae) in historical/heritage 

buildings were noted in Spain and Finland 

(Trobajo 1989, Viitanen and Pulkkinen 1989). 

WOOD PRESERVATIVE DEVELOPMENTS 

New generation organic formulations for 

mold and stain control were compared in a 

study from the United Kingdom (Williams and 

Lewis 1989). Acetylated wood has now found 

commercial application in Japan (Takahashi 

and others 1989). Proprionic acid is used to 

protect wood chips for export from South 

Africa (Ismail and others 1989). Other 

problems discussed included mention of the 

surface hardness resulting from CCA treatment 

of pine poles (Jonnsson and others 1989), 

increasing interest in the use of borates for 

decay protection and remedial treatment 

(Barnes and others 1989; Henningsson and 

others 1989), surface enhancement of wood 

with metal tannates (Plackett and Cronshaw 

1989), and performance of pressure-treated 

spruce in field trials (Hosli and Doyle 

1989). 

Again, many other topics of interest were 

presented at the IRG meeting in Finland in 

1989, but were not discussed at this meeting 

due to time constraints of the presentation. 

Interested persons should examine the Annual 

Proceedings of the American Wood Preservers' 

Association (AWPA) which lists titles of IRG 

papers, or contact the IRG Secretariat. 

ACKNOWLEDGMENTS 

Published as paper no. 17,467 of the 

contribution series of the Minnesota 

Agricultural Experiment Station based on 

research conducted under Project 43-69, 

supported by McIntire-Stennis funds. 

REFERENCES 

All references cited are published by the 

International Research Group on Wood 

Preservation, Drotting Kristinas vag 47C, S114 28, Stockholm, Sweden. 

Anonymous. 1988. IRG Statutes, Members, and 

Sponsors. Stockholm, Sweden: IRG 

Secretariat; 115 p. 

Barnes, H. M.; Amburgey, T. L.; Williams, L. 

H.; Morrell, J. J. 1989. Borates as wood 

preserving compounds: the status of 

research in the United States. 

IRG/WP/3542. 

Bech-Andersen, J. 1989. Serpula lacrymans the 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 5 
dry rot fungus: Revue on previous papers. 

IRG/WP/1393. 

Benko, R. 1989. Biological control of blue 

stain on wood with Pseudomonas cepacia 

6253: laboratory and field test. 

IRG/WP/1380. 

Bjurman, J. 1989. Effect of humidity 

fluctuations on mould growth on pine wood. 

IRG/WP/1412. 

Bruce, A.; King, B.; Highley, T. L. 1989. 

Decay resistance of wood removed from 

poles treated with Trichoderma. 

IRG/WP/1386. 

Daniel, G.; Pettersson, B.; Nilsson, T.; 

Volc, J. 1989. Cytoplasmic and 

extracellular localization of manganese II 

dependent peroxidase(s) in white rot fungi 

during degradation of woody materials. 

IRG/WP/1416. 

Doi, S.; Togashi, I. 1989. Utilization of 

nitrogenous substance by Serpula 

lacrymans. IRG/WP/1397. 

French, J.R.J. 1989. The case for 

non-chemical termite barriers in termite 

control? IRG/WP/1381. 

French, J.R.J.; LaFage, J. P. 1989. Termite 

standards questionnaire survey - Second 

report. IRG/WP/1395. 

Friis-Hansen, H.; Ludstrom, H. 1989. Soft rot 

in CCA-treated utility poles in Sweden. 

IRG/WP/1398. 

Fujii, Y.; Noguchi, M.; Imamura, Y.; Tokoro, 

M. 1989. Detection of termite attack in 

wood using acoustic emissions. 

IRG/WP/2331. 

Green, F.; Larsen, M. J.; Murmanis, L. L.; 

Highley, T. L. 1989. Proposed model for 

the penetration and decay of wood by the 

hyphal sheath of the brown-rot fungus 

Postia placenta. IRG/WP/1391. 

Henningsson, B.; Friis-Hansen, H.; Kaarik, 

A.; Edlund, M. L. 1989. Remedial 

ground-line treatment of CCA poles in 

service: a final report after 60 months' 

testing. IRG/WP/3534. 

Hosli, J. P.; Doyle, E. E. 1989. Performance 

of treated spruce in Canadian field test 

sites. IRG/WP/3506. 

Ismail, S.; Smith, E. J.; Baecker, A.A.W. 

1989. The use of propionic acid to prevent 

Pinus patula biodeterioration during 

outside chip storage in Zululand. 

IRG/WP/3531. 

Jonnsson, E.; Anette-Nilsson, E. M.; Ruddick, 

J.N.R. 1989. The effect of service life 

and preservative treatment on the hardness 

of wooden poles. IRG/WP/3537. 

Koch, A. P.; Kjerulf-Jensen, C.; Madsen, B. 

1989. New experiences with dry rot in 

Danish buildings, heat-treatment and 

viability tests. IRG/WP/1423. 

LaFage, J. P.; Delaplane, K. S. 1989. 

Variable chlordane residues in soil 

surrounding houses in Louisiana. 

IRG/WP/1404. 

Lawrence, A. H.; Ward, J.; Pettersen, J. C. 

1989. Identification of bacteria-infected 

red oak by ion mobility spectrometry. 

(Abstract of Poster in IRG/WP/5342; 

p.22.). 

Micales, J. A.; Richter, A. L.; Highley, T. 

L. 1989. Extracellular carbohydrate 

production by isolates of Postia (= Poria) 

placenta. 1989. IRG/WP/1388. 

Plackett, D. V.; Cronshaw, D. R. 1989. Wood 

surface pretreatments with metal tannates. 

IRG/WP/3552. 

Takahashi, M.; Imamura, Y.; Tanahashi, M. 

1989. Effect of acetylation on decay 

resistance of wood against brown rot, 

white rot, and soft rot fungi. 

IRG/WP/3540. 

Thornton, J. D. 1989a. The restricted 

distribution of Serpula lacrymans in 

Australian buildings. IRG/WP/1382. 

Thornton, J. D. 1989b. A new laboratory 

technique devised with the intention of 

determining whether, related to practical 

conditions, there should be a relationship 

between growth rate and decay capacity (of 

different strains) of Serpula lacrymans. 

IRG/WP/1384. 

Trobajo, E.L.R. 1989. Description of the 

damage produced by xilophagus 

curculionides in Spain. IRG/WP/1408. 

Trong, L. 1989. An attempt to grow dry rot 

fungus Serpula lacrymans on mortar 

substrate in non-sterile conditions. 

IRG/WP/1385. 

Viitanen, H.; Pulkkinen, M. 1989. The wood 

attacking insects in wooden houses of an 

old open air museum in southern Finland. 

IRG/WP/1409. 

Wiederhold, A. H.; Morrison, M.; Baecker, 

A.A.W. 1989. The colonization pattern of 

anaerobic fungi in wood. IRG/WP/1403. 

Williams, G. R.; Lewis, D. A. 1989. 

Observations on the colonization of 

freshly-felled timber treated with 

prophylactic chemicals by mould and 

sapstain fungi. IRG/WP/1394. 

Zahora, A. R.; Dickinson, D. J. 1989. 

Pretreatment decay in air-seasoning Scots 

and Corsican pine poles in England. 1989. 

IRG/WP/1390. 

6 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Need for Nondestructive Evaluation (NDE) in the Detection of 

Decay in Structures1 

W. Wayne Wilcox2 

Abstract: Examples of the need for nondestructive and 

remote sensing technologies for evaluating early stages of 

decay are presented. The need is critical to develop 

methods of analyzing internal decay, at the center of 

large wood members, and decay behind concealing 

coverings. Current technologies are reviewed and their 

inadequacies discussed. Acoustic emission and acousto­ ultrasonics appear to hold the greatest promise among 

existing technologies. 

Sometimes, nondestructive evaluation (NDE) is not 

needed to determine that a potentially serious decay

problem exists in a building. If the plywood siding, a

hand railing, or a major glulam beam sprouts mush- rooms (fig. 1), for example, you can be pretty sure you 

have a decay problem on your hands. Unfortunately,

those are rare occurrences. White mycelium growing on 

the surface of wooden structural members in moist areas 

(fig. 2) is also a pretty good clue that you should be 

concerned about the structural integrity of the member 

involved, but that, too, occurs relatively infrequently in

structures. Once the structure is opened and advanced 

Figure 1--Mushrooms on exterior glulam (courtesy of W.A. 

Dost). 

1

Presented at the Symposium on Current Research 

on Wood-Destroying Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 1989, Bend, Oregon. 

2

Professor of Forestry, Forest Products Pathologist, Forest Products Laboratory, University of California at 

Berkeley, Richmond, California 94804. 

Figure 2--Mycelial mat on joist and underside of plywood 

subfloor. 

decay is revealed, little additional information is 

necessary to assess the structural impact of the decay in

many cases. But, in the majority of cases of wooden 

structures with water problems, visual indicators are not 

present and some form of internal assessment must be 

incorporated. 

Two broad categories of internal decay are 

encountered in buildings. One is where wood is exposed 

to the weather and is sufficiently open that the surfaces 

of the wood members remain dry enough that any decay 

occurs inside the member without telegraphing to the 

surface (i.e., internal decay in exposed members). The 

second circumstance is where wooden structural 

components are contained behind surface finishes which 

effectively conceal any evidence of the decay process. 

Here are some examples of both such circum­ stances. 

An A-frame structure supported on glulam beams 

which extend beyond the perimeter walls and roof-line 

allowed the glulams to be subjected to internal decay

(fig. 3). No external evidence of decay was apparent, but

probing revealed sufficient softness to warrant concern for 

the structural integrity of the members. A combination of 

increment boring and ultrasonic pulse timing provided 

sufficient evidence of advanced decay to convince the 

engineer that reinforcement was required (fig. 4). 

Elsewhere, the entire Indian Valley College 

campus was temporarily condemned while exposed glulam 

beams were investigated and a structural solution was 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 7 
Figure 3--Glulam and connections exposed to the weather. 

Figure 4--Internal decay was found by boring and 

ultrasonic pulse timing. 

developed. This design proved particularly difficult, since 

glulams played such an important role in all structural 

aspects of the building, from lateral and vertical support 

to floor and roof support, blocking and decorative trim. However, even glulams used as nonstructural elements 

for their esthetic appeal can constitute life hazard if they

fail. Decay initiated in exposed parts of large members 

may extend past the perimeter wall, through load-bearing 

areas and into the interior of the structure. Although

evaluation of internal decay in exposed members 

currently presents significant challenges, at least it is 

possible; evaluation of decay which extends into the 

structure is often impossible without major demolition. These are two different challenges for NDE. 

For some time, there was a significant tendency on 

the part of designers to expose glulams to the weather on 

the outside of the building for esthetic reasons. We now 

know that this is not a good idea. Once the major check 

system develops in the top of a glulam in exterior 

exposure, it appears to be doomed. Even solid timbers 

exposed to the weather, with numerous contact points 

and bolt holes (fig. 5), present a significant hazard, 

because water is trapped long enough to be absorbed. 

Figure 5--Solid timber with internal decay around a 

bolt hole. 

In both of these cases (exposed glulams, and 

timbers with exposed joints and fastenings) it might be 

justifiable to just call for removal in any structure over 

six years old, and you would not be wrong too much of 

the time. However, because you would end up removing 

some perfectly sound wood if you operated that way, and

also because the people paying for such treatment usually

demand fairly firm evidence of a problem before being

willing to expend the large sums of money involved, some 

sort of internal property evaluation is necessary. As far 

as destructive sampling goes, if it turns out to be 

decayed, it does not matter that you have put a rather

large hole in it. However, if it turns out to be sound, 

then it would have been better to have had a non- destructive method of analyzing the interior of the 

member. Sometimes the life hazard involved in the failure of an individual wood structural member is so great 

that a means of continually monitoring its strength, as 

part of preventive maintenance, would be an extremely 

valuable tool. This is another role which NDE could play. 

In all the previous examples, at least portions of

the wood structural members were exposed to view. However, often, structural members are covered with a 

material which effectively conceals any evidence of the 

existence of a decay problem. Stucco probably is the most 

troublesome, and common, example of such covering. In 

one case, glulam beams and solid wood columns were 

encased in stucco and, in the corners, were affixed with 

planter boxes containing their own irrigation system. 

Unfortunately, this system irrigated both the soil and the 

supporting wood structure, causing decay (fig. 6) which 

was not at all evident behind the stucco (fig. 7). Although 

the prior example was inside a structure, stucco is most 

commonly used as an exterior finish. Both inside and out, stucco is just as concealing and, at the moment, requires 

actual demolition in order to assess the condition of wood 

beneath it. Remote, nondestructive assessment is truly

needed where stucco covers structural wood. 

An elastomeric compound, which mimics stucco, 

failed miserably when applied directly to plywood siding. Because it acted as a membrane, the cracks which developed let water in but the uncracked portions prevented 

it from getting back out. Therefore, it was both part of 

the decay problem and the concealment of the problem. 

8 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Figure 6--Decayed beam which was behind stucco as in 

Fig. 7. 

Figure 7--Stucco wall showing no external evidence of 

decay behind it. 

At the time of this writing, the most reliable field 

test available for diagnosing decay is the "pick test."

Unfortunately, it does not begin to become reliable until 

the equivalent of approximately 10-15 percent weight

loss, at which point a significant amount of wood 

strength has already been lost. Also, it is effective only

when decay is present on the surface, which is frequently 

not the case with major wood structural members in 

exposed service. An effective way of examining the inside 

of a large member is to use an increment borer. This 

instrument produces a core of actual wood from the 

interior of the member, which can be either visually 

examined or microscopically evaluated. Microscopical 

examination can effectively diagnose decay in its earliest 

stages, before significant loss in strength. However, it is 

an arduous, time-consuming and highly specialized 

technique which cannot be applied to a large number of 

wood members, and still leaves behind a hole. 

Probably the most commonly used device for 

detecting decay in the field is the screwdriver, or some 

other type of penetrating probe. Probing allows evaluation 

of both the hardness of the wood (a strength property not 

particularly sensitive to early stages of decay), and its 

toughness (which is very sensitive to early stages of 

decay) through application of the "pick test." When a 

building is undergoing evaluation for the presence of 

decay in structural members the screwdriver is likely to 

be present. However, information gained from probing

may be misleading. 

Properly evaluated and maintained, wooden buildings are capable of providing long service. Around 250 

years is about the best that we can show in this country.

But elsewhere, over 800 years can be demonstrated. 

The big problem is that most of the strength of 

wood is lost in such an early stage of decay that we have 

no current field-applicable technology capable of 

evaluating it with reliability. Professional judgment and 

experience may be our most effective current means of 

evaluating decay in structures. Actually, the intuitive 

expertise we've developed, out of necessity, may be an 

impediment to the development of electronic technology. A fairly recent survey by Barry Goodell and Oregon State 

University (Goodell and Graham, 1983) found that a 

majority of utility pole inspectors are confident that they 

can detect early stages of decay by hammer soundings! 

Moisture meters are used in the field, and can 

indicate whether wood is in a moisture condition capable

of supporting decay. Units with long insulated pins are 

capable of giving such information, even from the inside 

of a member. This technique, however, does not allow 

evaluation of strength loss. A sonic device has been in 

use, by utilities, on poles for many years and appears to 

be effective in locating advanced decay and voids. However, there is no information to suggest that it can detect 

early stages of decay. Experiments have shown that 

ultrasonic pulse transit time measurement is capable of 

detecting early stages of decay in some circumstances,

but not others (Wilcox, 1988). Acoustic emission under 

compression appears to be extremely sensitive to early 

stages of decay, but is not nondestructive (Beall and

Wilcox, 1987). Acousto-ultrasonics appears to be able to 

detect early stages of decay under nondestructive application, but has not yet been adequately researched to 

know for sure. (The primary difference between acoustic 

emission and acousto-ultrasonics is that acoustic emission 

testing involves analysis of sound being generated within 

a material being stressed, whereas acousto-ultrasonics 

involves analysis of sound which has traveled through the 

material but is induced by a source external to the 

material being tested.) Resonant vibration and electrical 

resistance methods may bear promise for nondestructive 

evaluation of wood structural members, but are just

beginning to be researched for this application. 

There is a need for more sensitive tools for 

inspecting wood structural members for damage zones 

and wood decay. Significant efforts are in progress to 

apply emerging technologies to the evaluation and 

inspection of wood members. These tools are being

developed considering the need to correlate NDE 

measurements with member strength and stiffness. 

Whether such technology can be developed for non- destructive application in structures remains to be seen. 

REFERENCES 

Beall, F.C.; Wilcox, W.W. 1987. Relationship of acoustic

emission during radial compression to mass loss 

from decay. Forest Products Journal 37(4):38-42. 

Goodell, B.S.; Graham, R.D. 1983. A survey of methods 

used to detect and control fungal decay of wood 

poles in service. The International Journal of Wood 

Preservation 3(2):61-63. 

Wilcox, W.W. 1988. Detection of early stages of wood 

decay with ultrasonic pulse velocity. Forest 

Products Journal 38(5):68-73. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 9 
Termites and Forest Management in Australia1

Don MG. Ewart2 

Abstract: Termites have long been 

regarded as major pests of Australian 

forests. Drawing together research on 

termite ecology and mammal conservation, 

this paper argues that this perception is 

wrong; termites are a vital component of 

native forests. 

Australian forests are dominated by 

eucalypts. More so than on any 

comparable landmass, Australian forests 

are characterized by members of this one 

genus comprising more than 450 species3. 

Eucalypts first appeared 35 million years 

ago, and are believed to have evolved on 

the margins of the then extensive 

rainforests. With climatic change and 

the retreat of rainforests in the late 

Tertiary, distinct seasons arose and the 

great radiation of the eucalypts began as 

adaptation to varying water supply became 

favored (White 1986). 

The second major genus of Australian 

forest trees is Acacia, the wattles. 

Although Australia has more than 600 

species of Acacia, they rarely dominate 

forests, and usually form an understory 

below a eucalypt canopy. Wattles are 

relatively resistant to termites, and 

standing wattles are mostly degraded by 

beetles. The third major genus, 

Callitris, is the only mainland 

1Presented at the Symposium on 

Current Research on Wood-Destroying 

Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 

1989, Bend, Oregon. 

2Lecturer, School of Early Childhood 

Studies, Institute of Education, The 

University of Melbourne, Priv. Bag 10, 

KEW VIC 3101, Australia. 

3Although Eucalyptus is still a 

single genus, revision of the genus was 

first suggested by Carr and Carr (1959). 

Pryor and Johnson (1971) recognized four 

subgenera which in a later (1981) paper 

they regarded as being equivalent to 

genera, but did not promote at that time. 

It is probably only a matter of time 

before the group is revised into at least 

four genera (Florence 1981). 

gymnosperm to form extensive forest and 

occurs widely in semi-arid regions of 

eastern Australia. Callitris is 

particularly resistant to degradation by 

termites4. 

Australia has very little forest. 

In a land mass of 760 million hectares, 

only 42.5 million hectares, less than six 

percent, are forested. These forests 

occur in a coastal belt, limited by 

rainfall (Senate 1977), and have been 

significantly fragmented since the 

arrival of Europeans. Inland Australia 

is arid, with vast areas of extremely 

sparse woodland where herbivory is 

generally unimportant and much of plant 

production goes directly to the 

detrivores. Termites are thus very 

important and these inland regions may be 

thought of as lightly wooded deserts with 

a fauna dominated by termites, ants and 

lizards. Recent studies (Tongway and 

others 1989) point to termites as 

promoters of small-scale fertile patches 

which are refuges for many desert plant 

species. 

LOSS OF TIMBER TO TERMITES--HISTORIC 

PERSPECTIVES 

The earliest records of termite 

damage to timber in Australia date from 

the late nineteenth century and report 

the impact of indigenous termites on 

introduced horticultural tree crops and 

vines (French 1893). At this time most 

of the timber produced by forest clearing 

was simply burnt, and it was not until 

the native forests were commercially 

harvested on a large scale that the 

activities of termites received 

attention. 

Thirty years ago--even five years 

ago-- I would have reported that termites 

are major pests in Australian forests, 

that they consume large quantities of 

merchantable timber and that the 

intensity of their attack is often much 

greater than in other bioregions (Carne 

4For tabulations of the durability 

of Australian timbers, see Johnson and 

others (1986). 

10 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
and Taylor 1978, Greaves and others 1967, 

Greaves 1962b, Harris 1966, Perry and 

others 1985, Ratcliffe and others 1952). 

The first researchers calculated the 

“cost” of termites in terms of the volume 

of timber lost" by surveying the extent 

of degraded timber that contained 

evidence of termite activity. Studies 

showed that in both highland and lowland 

forests, termites "reduced" timber yield 

by 25 percent or more (Greaves and others 

1965, 1967). This indicated loss in 

potential profitability lead to novel 

control proposals, including the treating 

of individual trees with arsenic trioxide 

or organochlorines applied by injection, 

the removal of all mature trees that 

might potentially harbour termites and 

the replacement of susceptible native 

forest with plantations of Pinus spp. 

(Greaves 1959, Greaves and others 1967). 

However, with the exception of conversion 

to pines, none of these termite control 

measures have ever been economically 

feasible. 

In the main, only five termite 

species are responsible for almost all of 

the attack in commercial Australian 

forests. The primitive Giant Northern 

Termite (Mastotermes darwiniensis 

Froggatt) (Mastotermitidae) is a major 

impediment to tropical forestry, the 

dampwood termite (Porotermes adamsoni 

[Froggatt]) (Porotermitidae) occurs in 

cool or mountainous forests along the 

eastern seaboard, but by far the most 

important are of the genus Coptotermes 

Wasmann (Rhinotermitidae): 

C. acinaciformis Froggatt (C.a. raffrayi 

in Western Australia), C. frenchi Hill 

and C. lacteus (Froggatt). 

Species of Coptotermes are very 

adaptable; they may nest in the ground, 

in mounds of their own construction, or 

in trees. Their distribution in 

Australia is almost as wide as the 

eucalypts they eat: desert, woodland, 

cool temperate forest and rainforest 

(Calaby and Gay 1959). 

ATTACK ON TREES 

Termites prefer to consume decayed 

wood (Wood 1978, French and others 1981, 

1987) and there is evidence that they are 

healthier if they do (Hendee 1935, Lenz 

and others 1980). Attack on trees is 

more likely to occur when the tree is 

wounded (Greaves and others 1965). 

Colony formation by founding-pairs is 

through scar tissue, typically reported 

to be fire scars at the base of trees 

(Greaves and others 1965, Perry and 

others 1985), but entry through less 

easily observed routes such as branch 

stubs, damaged roots and the exit holes 

of beetles and moths is also probable. 

Attack is also initiated when termites 

extend galleries in the soil and enter 

other trees, typically from galleries 

running on the underside of roots and 

entering the heartwood at the root crown, 

a habit common in Coptotermes. This 

method of attack may occur over distances 

of 50 meters with a single colony feeding 

on more than 15 trees (Greaves 1962a) and 

is eased by the high incidence of natural 

root grafting among eucalypts (Ashton 

1975). 

Coptotermes build a central nest, at 

the base of the tree, with the nursery 

being below ground level in cool climates 

and elevated in warmer areas. The 

termites consume the heartwood, as its 

natural anti-feedant chemicals degrade 

through decay organisms and natural 

ageing. Porotermes consume the timber in 

a similar manner, but do not maintain a 

central nest, rather, they work through 

the tree as a travelling population. 

Thus the main "pest" species are 

consuming dead and decayed heartwood and 

decayed areas of timber which are of 

negligible commercial value. Rather than 

being primary agents of timber 

degradation, their presence is secondary: 

an effect rather than a cause. Timber is 

not a limiting resource for the termites, 

but appropriately degraded timber is; 

termites select their food for the 

presence of appropriate decay. 

Shigo's model of compartmentalization of decay in trees (CODIT) 

(Shigo 1984) is widely ignored by 

Australians (see, for example, Perry and 

others 1985), but the patterns of termite 

activity in eucalypt timber closely 

follow Shigo's predicted areas of 

response. His model is particularly 

useful in understanding the coevolutionary balance between termites and 

trees: although termites feed within the 

tree, the tree is able to limit their 

activity and protect its structural 

integrity, by compartmentalizing scar 

tissue. It does a tree no harm to be 

hollowed and may even provide some 

structural advantage (Dickinson and 

Tanner 1978, Janzen 1976). The longevity 

of termite infested eucalypts show that 

this balance between growth and 

consumption may be held for more than two 

centuries, with the process of hollowing 

extending into all the main branches. 

Early growth of eucalypts 

concentrates on the attainment of height. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 11 
Crown growth dominates mid-life, with 

maturity occurring when the crown reaches 

the limits of dimensional stability. The 

term “overmature” is used to describe 

trees where the growth of the crown is 

balanced by more or less continual branch 

shedding. Most young trees do not suffer 

termite infestation until about 70 cm 

dbhob5 although the risk is greater 

where injuries have occurred (Carne and 

Taylor 1978, Elliott and Bashford 1984, 

Mackowski 1984). 

Fire is considered to be the major 

cause of such injury (Elliott and 

Bashford 1984, Perry and others 1985), 

particularly when prescribed burning is 

involved. Even where eucalypts are 

planted as exotics, termite attack is 

secondary to some other stress-causing 

factor (Chatterjee and Singh 1967). Any 

significant breach of the tree's defences 

will result in the formation attractive 

scar tissue. Thus today, a tree's 

chances of early termite infestation are 

increased by roading and logging 

machinery, which cause mechanical damage 

to the cambium at the base of trees and 

also, by logging and silvicultural 

thinning due to collisions with falling 

trees. 

However, my observations in the 

Boola Boola State Forest in eastern 

Victoria (Ewart 1988) suggest that 

regrowth is being rotated while it is too 

small to support large colonies of the 

major pest species. These termites 

require large timber for nesting, and 

attack on small regrowth trees is most 

commonly initiated from colonies located 

in remnant old-growth trees or stumps. 

Thus while management may make more 

palatable timber available to termites, 

the populations of termites will diminish 

drastically, unless sufficient colonysites remain. 

SPECIES DEPENDENT ON TERMITE-CREATED 

HOLLOWS 

The excavations of termites alter 

the structure of trees and provide spaces 

which have become a necessary part of the 

habitat of many vertebrate species. 

These beneficial activities are 

increasingly recognized by wildlife 

researchers (Ambrose 1982, Mackowski 

1984, Saunders 1979) but remain largely 

ignored by termite biologists (e.g. 

McMahan 1986). Termites do not create 

these hollows directly; their 

excavations, apart from the minimum space 

5Diameter Breast Height Over Bark. 

needed for access, are quickly filled 

with mud and feces ("mudgut”). Mudgut 

pipes may extend the full height of the 

tree and into each of the major limbs. 

Eventually the mudgut column compacts 

under its own weight or erodes as water 

enters through openings created by shed 

branches. This creates cavities which 

other animals readily utilize. 

A wide range of bats, birds and 

arboreal marsupials are entirely 

dependent on hollows of particular 

volume, depth and opening diameter for 

nest sites. Australian vertebrates, 

unlike some of their northern hemisphere 

counterparts, do not excavate their own 

tree hollows but are limited in their 

efforts to minor maintenance, relying 

instead on the actions of termites. 

Fallen, hollowed limbs and trunks of 

overmature trees provide habitat for 

ground-dwelling reptiles and mammals. A 

particular example of this is the 

specialist termite eater, the Numbat 

(Myrmecobius fasciatus Waterhouse) 

(Marsupialia: Myrmecobiidae). Numbats 

feed exclusively at secondary 

aggregations of termites on the forest 

floor and require numerous hollow logs 

for shelter. They were once widespread 

across southern Australia, but their 

range has now been reduced to a small 

area of southwestern Australia due to the 

loss of habitat (Christensen and others 

1984, Friend 1982). Wildfire and logging 

reduce the supply of suitably hollowed 

fallen wood and without shelter, numbats 

quickly fall prey to the introduced 

European foxes. 

FUTURE MANAGEMENT CONSIDERATIONS 

Typically, a eucalypt does not 

develop hollows until between 90 to 120 

years old, well after the age at which 

termites begin to feed, but also well 

beyond the present 40 to 80 year age at 

rotation. Management prescriptions call 

for the retention of a few overmature 

"habitat" trees in each logging coupe. 

However, although eucalypts may persist 

for two to three centuries after 

developing hollows, they will in time die 

and eventually fall. Thus the 

prescriptions are inadequate because they 

make no provision for recruitment to 

replace these habitat trees as they are 

lost. 

The impending threat to wildlife 

populations is potentially serious. 

Populations will decline rapidly as nest 

sites become limiting. Even if 

corrective action is taken immediately, 

many forests will soon face a gap of a 

12 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
century or more before another generation 

of suitably hollowed trees can develop 

(Mackowski 1984). 

This problem is compounded by the 

negative effects of logging on the 

retained habitat trees: few will be able 

to live to their full potential as the 

coupes in which they stand will be logged 

between three and seven times during this 

period. The cost of providing artificial 

hollows during this period will be 

enormous. Thus in areas where multiple 

use management includes the maintenance 

of wildlife, there is a need to retain 

not just habitat trees but also cohorts 

of replacement trees and populations of 

termites to transform them. Managers of 

native eucalypt forest need to change 

their perception of termites: termites 

are not pests, but have a vital role in 

forest ecology and must be seen as an 

intrinsic part of the system. 

REFERENCES 

Ambrose, G.J. 1982. An ecological and 

behavioural study of vertebrates 

using hollows in eucalypt branches. 

PhD thesis, Department of Zoology, 

La Trobe University, Victoria, 

Australia. 

Ashton, David H. 1975. Studies of litter 

in Eucalyptus regnans forests. 

Australian Journal of Botany 23: 

413-433. 

Calaby, J.H.; Gay, F.J. 1959. Aspects of 

the distribution and ecology of 

Australian termites. In: 

Bodemheimer, F.S.; Weisbach, W.W., 

eds. Biogeography and ecology in 

Australia. The Hague: Junk; 211-

233. 

Carne, P.B.; Taylor, K.L. 1978. Insect 

pests. In: Hillis, W.E.; Brown, 

A.G., eds. Eucalypts for wood 

production. Melbourne, Australia: 

CSIRO; 155-168. 

Carr, D.J.; Carr, S.G.M. 1959. Floral 

morphology and taxonomy of 

Eucalyptus. Nature 184: 1549-1552. 

Chatterjee, P.N.; Singh, P. 1967. 

Preliminary observations on die-back 

and termite attack in eucalypts 1-3 

years old in New Forest plantation. 

Proceedings of the All India 

symposium on fast growing tree 

species, Dehra Dun: 1-2. 

Christensen, P.; Maisey, K.; Perry, D.H. 

1984. Radiotracking the Numbat, 

Myrmecobius fasciatus, in the Perup 

forest of Western Australia. 

Australian Wildlife Research 11: 

275-288. 

Dickinson, T.A.; Tanner, E.V.J. 1978. 

Exploitation of hollow trunks by 

tropical trees. Biotropica 10(3): 

231-233. 

Elliott, H.J.; Bashford, R. 1984. 

Incidence and effects of the 

dampwood termite Porotermes 

adamsoni, in two Tasmanian east 

coast eucalypt forests. Australian 

Forestry 47(1): 11-15. 

Ewart, Don McG. 1988. Aspects of the 

ecology of the termite Coptotermes 

lacteus (Froggatt). PhD thesis, 

Department of Zoology, La Trobe 

University, Victoria, Australia. 

Florence, R.G. 1981. The biology of a 

eucalypt forest. In: Pate, J.S.; 

McComb, A.J., eds. The biology of 

Australian Plants. Nedlands: 

University of Western Australia 

Press; 147-180. 

French, C. 1893. A handbook of the 

destructive insects of Victoria, 

with notes on the methods to be 

adopted to check and extirpate them. 

Part II. Melbourne: Government 

Printer; 222p. 

French, John R.J.; Donaldson, R.; Ewart, 

Don McG. 1987. Electronic 

monitoring of temperatures in air, a 

termite mound, trees and soil. 

Australian Forestry 17: 79-82. 

French, J.R.J.; Robinson, P.J.; Bartlett, 

N.R. 1981. A rapid and selective 

field assessment of termite feeding 

preference of the subterranean 

termite Heterotermes ferox (Frogg.) 

using toilet roll and small 

wood-block baits. Sociobiology 

6(2): 135-151. 

Friend, T. 1982. The Numbat - an 

endangered specialist. Australian 

Natural History 20(10): 339-342. 

Greaves, T. 1959. Termites as forest 

pests. Australian Forestry 23: 

114-120. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 13 
Greaves, T. 1962a. Studies of foraging 

galleries and the invasion of living 

trees by Coptotermes acinaciformis 

and C. brunneus (Isoptera). 

Australian Journal of Zoology 10: 

630-651. 

Greaves, T. 1962b. Termites in 

Australian forests. Proceedings of 

the 11th International Congress of 

Entomology 1960; Vienna; 238-240. 

Greaves, T.; Armstrong, G.J.; McInnes, 

R.S.; Dowse, J.E. 1967. Timber 

losses caused by termites, decay and 

fire in two coastal forests in New 

South Wales. Technical Paper, 

Division of Entomology, CSIRO 

Australia 7: 2-18. 

Greaves, T.; McInnes, R.S.; Dowse, J.E. 

1965. Timber losses caused by 

termites, decay and fire in an 

alpine forest in New South Wales. 

Australian Forestry 29(3): 161-174. 

Harris, W.V. 1966. On the genus 

Coptotermes in Africa (Isoptera: 

Rhinotermitidae). Proceedings of 

the Royal Entomological Society, 

London. Ser. B. 35: 161-171. 

Hendee, E.C. 1935. The role of fungi in 

the diet of the common damp-wood 

termite Zootermopsis angusticollis. 

Hilgardia 9(10): 499-525. 

Janzen, D.H. 1976. Why tropical trees 

have rotten cores. Biotropica 8(2): 

110. 

Johnson, G.C.; Thornton, J.D.; Saunders, 

I.W. 1986. An in-ground natural 

durability field test of Australian 

timbers and Australian Reference 

species. Material and Organismen 

21(4): 251-264. 

Lenz, M.I.; Ruyooka, D.B.A.; Howick, C.D. 

1980. The effect of brown and white 

rot fungi on wood consumption and 

survival of Coptotermes lacteus 

(Froggatt) (Isoptera: 

Rhinotermitidae) in a laboratory 

bioassay. Zeitschrift für 

Angewandte Entomologie 89: 344-362. 

Mackowski, C.M. 1984. The ontogeny of 

hollows in Blackbutt (Eucalyptus 

pilularis) and its relevance to the 

management of forests for possums, 

gliders and timber. In: Smith, 

Andrew P.; Hume, Ian D., eds. 

Possums and gliders. Sydney: 

Australian Mammal Society; 553-567. 

McMahan, E.A. 1986. Beneficial aspects 

of termites. In: Vinson, S. 

Bradleigh, ed. Economic impact and 

control of social insects. New 

York: Praeger; 144-164. 

Perry, D.H.; Lenz, M.I.; Watson, J.A.L. 

1985. Relationships between fire, 

fungal rots and termite damage in 

Australian forest trees. Australian 

Forestry 48(1): 46-53. 

Pryor, L.D.; Johnson, L.A.S. 1971. A 

Classification of the eucalypts. 

Canberra: Australian National 

University Press. 

Pryor, L.D.; Johnson, L.A.S. 1981. 

Eucalyptus, the universal 

Australian, In: Keast, A., ed. 

Biogeography and ecology in 

Australia. The Hague: Junk. 

Ratcliffe, F.N.; Gay, F.J.; Greaves, T. 

1952. Australian termites. 

Melbourne: CSIRO Australia; 124 p. 

Saunders, D.A. 1979. The availability 

of tree hollows for use as nest 

sites by White-tailed Black 

Cockatoos (Calyptorhynchus baudinii 

latirostris). Australian Journal of 

Wildlife Research 6: 205-216. 

Senate. 1977. Woodchips and the 

environment: Report from the Senate 

Standing Committee on Science and 

the Environment. Canberra: 

Australian Government Publishing 

Service; 454 p. 

Shigo, A.L. 1984. Compartmentalization: 

a conceptual framework for 

understanding how trees grow and 

defend themselves. Annual Review of 

Phytopathology 22: 189-214. 

Tongway, D.J.; Ludwig, J.A.; Whitford, 

Walter G. 1989. Mulga log mounds: 

fertile patches in the semi-arid 

woodlands of central Australia. 

Australian Journal of Ecology 

14(3):263-268. 

White, Mary E. 1986. The Greening of 

Gondwana. Frenchs Forest, New South 

Wales: Reed; 256. 

Wood, Tom G. 1978. Food and feeding 

habits of termites. In: Brian, M.V. 

ed., Production ecology of ants and 

termites. Cambridge: Cambridge 

University Press; 55-80. 

14 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Cuticular Hydrocarbons: Species and Population-Level 

Discrimination in Termites1 

Michael I. Haverty Marion Page Barbara L. Thorne Pierre Escoubas2 

Abstract: Hydrocarbons in the cuticle of insects are essential in 

protecting them from desiccation. The vast variety of hydrocarbons synthesized by insects and the apparent species-specificity 

of cuticular hydrocarbon mixtures make them excellent taxonomic characters for separating species within termite genera. 

Hydrocarbon phenotypes of dampwood termites, Zootermopsis, 

correspond to species diagnoses. A morphological character, the 

subsidiary tooth of the right mandible, was found that correlates 

exactly with the hydrocarbon phenotypes of the three described 

species of Zootermopsis. Two distinct hydrocarbon phenotypes 

within Z. nevadensis have been used to identify a new subspecies, Z. n. nuttingi, which is morphologically indistinguishable 

from its conspecific, Z. n. nevadensis. This subspecies designation was corroborated with studies of agonistic behavior. Preliminary data suggest that cuticular hydrocarbons might be 

similarly used to sort specimens and to search for morphological 

characters within the subterranean termite genus Reticulitermes. 

This may facilitate a revision of this important genus. Cuticular 

hydrocarbon profiles enabled population-level discrimination of 

the Formosan subterranean termite, Coptotermes formosanus, 

from different geographic locations. 

The outer layer of the cuticle of all terrestrial insects 

consists of a thin layer of wax (Hadley 1985). This wax plays a 

key role in survival of the insect by providing protection from 

desiccation (Hadley 1980), as well as serving as a barrier to 

abrasion, microorganisms, and chemicals (Blomquist and 

Dillwith 1985). Hydrocarbons are ubiquitous components in 

insect cuticular lipids and can comprise up to 90 percent of the 

material (Blomquist and Dillwith 1985, Hadley 1985). They 

have been shown to be important semiochemicals, and have 

been postulated as species and caste recognition cues in termites 

(Howard and Blomquist 1982). 

Alkanes occur in all insect surface lipids investigated so far. 

n-Alkanes generally range from 21 to 36 carbon atoms, and an 

odd number of carbons predominate. Terminally-branched and 

internally-branched monomethylalkanes are also prevalent in 

1

Presented at the Symposium on Current Research on Wood-Destroying 

Organisms and Future Prospects for Protecting Wood in Use, September 13, 

1989, Bend, Oregon. 2

Project Leader and Principal Research Entomologist, respectively, Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. 

Department of Agriculture, Berkeley, Calif.; Adjunct Assistant Professor, 

Department of Biology, Northeastern University, Boston, Mass., and Research 

Associate, Museum of Comparative Zoology, Harvard University, Cambridge, 

Mass.; Research Associate, Plant-Animal Interactions Research Group, Mizutani 

Plant Ecochemicals Project, Research Development Corporation of Japan, 

Eniwa-shi, Hokkaido, Japan. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 

insect surface lipids and range from simple compositions, in 

which only one compound is present, to complex mixtures 

(Blomquist and Dillwith 1985). In most monomethylalkanes, 

the methyl branch is located on an odd-numbered carbon atom 

between carbons 3 and 17. As careful analyses of mono-, di- and 

trimethylalkanes are made on more organisms, it appears that 

the methyl groups can be positioned almost anywhere on the 

chain. n-Alkenes, with one, two, or three double bonds, have 

been characterized in about one-half of the insect species examined to date. The chain length of cuticular n-alkenes usually 

ranges from 20 to 37 carbon atoms, with odd-numbered chain 

lengths predominating. The position of the double bond can be 

almost anywhere in the chain, but is common at carbon 9 

(Blomquist and Dillwith 1985). 

HYDROCARBONS AS TAXONOMIC CHARACTERS 

Moore (1969) was the first to report the composition of 

cuticular hydrocarbons in a termite, Nasutitermes exitiosus 

(Hill) (Nasutitermitidae). He found the majority of the hydrocarbons to be paraffins from C24 to C47 with compounds with an odd 

number of carbons in the parent chain predominating. Blomquist and 

others (1979) and Howard and others (1978, 1980 and 1982) 

completely characterized the cuticular hydrocarbons of three 

termite species. They found that R. flavipes (Kollar). R. virginicus 

(Banks) (Rhinotermitidae), and Z. angusticollis (Hagen) 

(Termopsidae) possess drastically different hydrocarbon profiles, and all three of these profiles differ markedly from those 

reported earlier for N. exitiosus (Hill). Those investigators 

postulated that hydrocarbons might serve as semiochemical 

cues for caste and species recognition. On the basis of these early 

results, Howard and Blomquist (1982) hypothesized that each 

insect species had a mixture of cuticular hydrocarbons that was 

peculiar to that species and potentially useful as taxonomic 

characters. 

Insects synthesize most if not all of their complement of 

cuticular hydrocarbons de novo (Blomquist and Dillwith 1985). 

We assume this synthesis is genetically controlled and is affected only slightly by environmental parameters. Insect species 

generally have from 10 to 40 major components in their hydrocarbon mixtures. The relatively large number of possible hydrocarbon components found in the cuticle of insects, ease of 

chemical analysis and identification of hydrocarbons, and apparent species-specific compositions for many insects make 

hydrocarbons attractive characters for use in chemotaxonomy 

(see references in Haverty and others 1989 and Page and others 

1990). 

15 
We consider hydrocarbons to be unnecessary for higher 

order taxonomic separations. Obvious and consistent morphological characters will usually suffice. If there are qualitative 

differences among species within a genus, a reasonable goal 

would be to develop a dichotomous key to the species. Useful 

hydrocarbons should be abundant, not minor components (at 

least 1 percent, but preferably > 5 percent of the total hydrocarbon mixture). They should also be unique or present in only a 

few of the species, or conversely, they should be common in 

most of the species yet completely absent, rare or of insignificant 

quantities in one or a few. Furthermore, they should have a 

unique elution time so that they do not coelute with another 

hydrocarbon in the same species, nor should they elute at a time 

similar to that of a different hydrocarbon in a different species. 

From a collection of these hydrocarbons, many different dichotomous keys are possible. 

For the most part we have been corroborating existing 

taxonomies that are based on morphological, genetic and/or 

behavioral characteristics. For example, we have helped unravel 

species complexes, identified sibling species and substantiated 

recent synonymies in cone beetles, genus Conophthorus (Haverty 

and others 1989, Page and others 1990). Ideally, we should use 

these chemical characters much as classical taxonomists use 

morphology, behavior or genetics, i.e., to sort the groups of 

insects on the basis of chemical characters first, rather than after 

groups have already been sorted on the basis of existing 

(nonchemical) character criteria. 

That is how we initially started working on the cuticular 

hydrocarbons of termites. While trying to understand a synonymy of two species of cone beetles, C. ponderosae Hopkins 

and C. lambertianae Hopkins, we decided to use cuticular 

hydrocarbons as taxonomic characters. To test our methodology 

we examined the hydrocarbons of the dampwood termite, Z. 

angusticollis, which had been characterized in the literature 

(Blomquist and others 1979). We found our results to be qualitatively similar, yet quantitatively very different from those 

reported by Blomquist and others (1979). Furthermore, our 

termite specimens were identified as Z. nevadensis, not Z. 

angusticollis. Additional collections and analyses led us to 

identify an "extra" hydrocarbon phenotype of Zootermopsis 

(Haverty and others 1988), and to find a morphological character for unequivocal identification of the three described species 

of Zootermopsis (Thorne and Haverty 1989). 

These serendipitous discoveries have encouraged us to 

continue our work on termites as well as other groups of 

economically important forest insects. We have found that 

characterization of cuticular hydrocarbons often leads to subsequent biological or chemical studies which clarify taxonomic 

questions. 

CHARACTERIZATION OF CUTICULAR 

HYDROCARBONS 

Detailed descriptions of collection and extraction procedures for specific termite species have been published elsewhere 

(Blomquist and others 1979, Howard and others 1978, 1982, 

1988, Haverty and others 1988, 1990). Cuticular lipids are 

extracted by immersing 15 to 500 termites (depending on size 

and total quantity of cuticular hydrocarbon), as a group, in 2 to 

10 ml of hexane for 10 min. After extraction, hydrocarbons are 

separated from other components by pipetting the extract and an 

additional 2 to 8 ml of hexane through 3 cm of activated BioSilA in Pasteur pipette mini-columns. Hydrocarbon extracts are 

evaporated to dryness under a stream of nitrogen and redissolved 

in 30 to 100 p of hexane for GC-MS analyses. When termites are 

extracted in the field, the hexane extracts can be allowed to fully 

evaporate. Dried extracts can then be easily shipped to the 

laboratory for chromatographic analysis. These field-dried extracts are redissolved in 10 ml of hexane and processed as usual. 

If termites are frozen, they should be removed from the freezer 

and allowed to warm to ambient temperature before extraction. 

After extraction, insects should be stored in 70 percent ethanol 

for later identification by morphological features and to serve as 

voucher specimens. All voucher specimens should be deposited 

in an appropriate reference museum. 

All of our extractions were accomplished as described 

above. Our gas chromatography-mass spectrometry (GC-MS) 

analyses have been performed on a Hewlett Packard 5890 gas 

chromatograph equipped with a Hewlett Packard 5970B Mass 

Selective Detector interfaced with Hewlett Packard Chemstation 

computer. The GC-MS was equipped with a fused silica capillary column (30 m x 0.2 mm ID, HP-1) and operated in split 

mode (with a split ratio of 8:1 to 20:1). Each mixture is analyzed 

by a temperature program from either 150°C, or 200°C to 320°C 

at 3°C/min with a final hold of 10 to 20 minutes. Electron impact 

(EI) mass spectra were obtained at 70 eV. n-Alkanes were 

identified by comparing their retention times and mass spectra 

with external standards (n-C22, n-C24, n-C28, and n-C32). Alkenes 

and methyl-branched alkanes were tentatively identified by 

calculating their equivalent chain lengths; mass spectra of 

methylalkanes were interpreted as described by Blomquist and 

others (1987). 

SORTING SPECIMENS BY HYDROCARBON MIXTURES 

The best example of the use of cuticular hydrocarbons as 

taxonomic characters for termites is the study we initiated with 

the dampwood termites, Zootermopsis (Haverty and others 

1988). In preliminary work we collected what we tentatively 

identified as colonies of Z. angusticollis (Hagen) from the 

vicinity of Burney, Calif., in the Lassen National Forest, and 

extracted their cuticular hydrocarbons. We identified the same 

hydrocarbon components as published by Blomquist and others 

(1979), but in markedly different proportions. This was our first 

clue that considerable intraspecific variation might exist in the 

mixtures of cuticular hydrocarbons of Zootermopsis, and 

prompted us to examine this genus more thoroughly. 

16 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
The current taxonomy of the genus Zootermopsis recog- Table 1—Diagnostic hydrocarbons identified from four phenotypes of 

nizes three species: Z. nevadensis, Z. angusticollis, and Z. Zootermopsis (from Haverty and others 1988) 

laticeps (Banks) (Emerson 1933, Sumner 1933, Weesner 1970). Phenotype1 

We identified four consistent, unique cuticular hydrocarbon 

phenotypes from the three described species. Phenotype I (Z. Hydrocarbon2 ECL3

 I II III IV 

nevadensis) contains large amounts (ca. 10 percent of the total 

hydrocarbon) of the symmetrical dimethylalkane 5, 17- 9-, 11-MeC21 21.37 0 ++ 0 Tr 

dimethylheneicosane (fig. 1). This dimethylalkane is not found 2- or 4-MeC21 21.62 0 0 0 ++ 

in any other phenotype (table 1). 5,17-DimeC21 22.04 +++ 0 0 0 

Phenotype II (Z. angusticollis) has the most complex hydro- 3,11 ; 3,13-DimeC21 22.11 0 +++ 0 0 

carbon mixture, sharing many of the components eluting before n-C2323:1 22.70 0 0 ++ ++ 

n-nonacosane with at least one of the other three phenotypes 

(Ha

many unique compounds in quantities greater than 1 percent 2- or 4-MeC28 28.60 0 ++ 0 0 

(table 1): an isomeric mixture of 9- and 11-methylheneicosane; 2- or 4-MeC331 31.75 0 ++ 0 0 

3,11- and 3, 13-dimethylheneicosane; 3, 11- and 3, 13- 7,11-DimeC35 35.70 0 0 0 ++ 

dimethyltricosane; 2- or 4-methyloctacosane and 2- or 4- 7,13-DimeC39 38.53 0 0 0 ++ 

verty and others 1988). However, phenotype II possesses 3,11-, 3,13-DimeC23 24.10 0 ++ 0 0 

methyihentriacontane. 1

 A triple + indicates > 5.0 percent of the total hydrocarbon component and 

++ from 1.0 to 5.0 percent of the total. Trace (Tr) components appear

infrequently or consistently in very small quantities (< 0.5 percent of the total). 

A zero indicates the hydrocarbon was never identified for the phenotype. 2

 Carbon number is the total number of carbons in the parent chain, 

excluding the methyl groups. 3

 ECL = Equivalent chain length. 

Figure 1―Gas chromatograms of the surface hydrocarbons of four phenotypes of Zootermopsis. Numbers identify 

peaks characterized by Haverty and others (1988). 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 17 
Phenotype III (Z. nevadensis) clearly contains the simplest 

hydrocarbon profile. Only 10 hydrocarbon components are 

present in significant quantities (greater than 1.0 percent of the 

total hydrocarbon fraction). This is the only phenotype we 

collected from the Pacific Coast with an olefin (tricosene). All 

of the other major (>5.0 percent) or significant (>1.0 percent) 

components of Phenotype III are shared with at least one of the 

other phenotypes (Haverty and others 1988). 

Phenotype IV (Z. laticeps) is also fairly simple, with only 13 

significant (1.0 percent of total hydrocarbon) components, and 

is quite similar to Phenotype III. The major differences are the 

three unique compounds: 2- or 4- methylheneicosane; 7, 11-

dimethylpentatriacontane and 7,13-dimethylheptatriacontane 

(table 1). 

Identification of four consistent, unique cuticular hydrocarbon phenotypes from three extant species was in conflict with 

the species-specific hypothesis put forward by Howard and 

others (1978, 1982). If cuticular hydrocarbon profiles are truly 

species-specific, then there is at least one new, undescribed 

species of Zootermopsis. It appears that Z. angusticollis and Z. 

laticeps are valid species, but Z. nevadensis is a complex of at 

least two species or one species with polymorphic hydrocarbon 

chemistry. Clarification of specific status of each phenotype 

required many different approaches. The approaches we investigated were correlation of hydrocarbon chemistry and external 

morphology from an extensive geographic collection (Thorne 

and Haverty 1989), bioassays of aggressive behavior (Haverty 

and Thorne 1989), isoenzyme analysis (Korman and others, 

1991), and DNA hybridization (Broughton 1989). 

CORRELATION OF HYDROCARBONS WITH 

EXTERNAL MORPHOLOGY 

Determination of Zootermopsis species on the basis of 

morphology is often equivocal, especially in juvenile or small 

colonies. However, by sorting specimens on the basis of cuticular hydrocarbon phenotypes, we found a character on the right 

mandible, the shape and position of the subsidiary tooth, that 

enables unequivocal diagnosis of Z. angusticollis, Z. nevadensis 

and Z. laticeps (Thorne and Haverty 1989). This small subsidiary tooth is present at the base of the anterior edge of the first 

marginal tooth on the right mandible of nonsoldiers of all genera 

within the Termopsidae. Shape and position of the subsidiary 

tooth can be consistently and accurately used to diagnose both 

sexes of all nonsoldier morphs of Z. angusticollis and Z. 

nevadensis. 

Because the subsidiary tooth character does not rely on a 

series of soldiers (relatively rare in colonies or collections) or 

alates (only present seasonally and absent from most samples or 

collections), it can be used to determine virtually any collection 

of Zootermopsis. Large larvae or nymphs are almost always 

abundant, and dissection of several individuals will not reduce 

the value of the collection. The mandible structure does not 

enable morphological discrimination of the two Z. nevadensis 

hydrocarbon phenotypes. However, agonistic behavior which 

involves social interactions between individuals, including fighting, fleeing, or submitting, provides a biological model for 

species discrimination. 

AGONISTIC INTERACTIONS BETWEEN 

HYDROCARBON PHENOTYPES 

Termites show a wide range of agonistic behaviors when 

interacting with other termites from a different colony of the 

same or a different species. Aggressive encounters are often 

particularly dramatic because of defensive morphological modifications of the soldier caste and effective use of strong mandibles by the pseudergate or worker castes. Interspecific aggression is common in termite-termite interactions. Intraspecific 

aggression (between colonies) has also been shown in a variety 

of other termites. A few documented cases exist, however, in 

which aggression between conspecific termites is absent; i.e., 

where individuals from different colonies can be mixed with 

little or no reaction (see references in Haverty and Thorne 1989). 

Three experiments were conducted to assess agonistic 

interactions between hydrocarbon phenotypes (Haverty and 

Thorne 1989). We hypothesized that meetings between termites 

from colonies of like phenotypes would be more passive than 

encounters between individuals of different phenotypes. In the 

first series of experiments we assessed the agonistic response of 

soldiers from each of the three hydrocarbon phenotypes with 

nymphs from each phenotype. In the second we assessed the 

intra-caste agonistic behavior of either pseudergates or soldiers 

from hydrocarbon phenotypes I, II, and III. In the third we 

assessed the intra-caste agonistic behavior of pseudergates or 

soldiers from hydrocarbon phenotype IV with those like castes 

from phenotypes I, II, and III. 

Our results demonstrated that soldiers or pseudergates 

seldom attack individuals of the same hydrocarbon phenotype. 

Phenotype II (Z. angusticollis) is typically aggressive toward 

phenotype III (Z. nevadensis), but not always aggressive against 

phenotype I (Z. nevadensis). The variation in response is dependent on which castes are placed in the bioassay arena: soldierversus-soldier bouts result in consistent aggression, while 

pseudergate-versus-pseudergate or soldier-versus-nymphs contacts do not. Both pseudergates and soldiers of Z. laticeps 

(phenotype IV) respond agonistically toward the other three 

phenotypes. 

Although hydrocarbon phenotypes I and III, both Z. 

nevadensis, are morphologically indistinguishable, agonistic 

behavioral responses between them are not equivalent to Iversus-I or III- versus-III behavioral responses. We interpret the 

lack of avoidance or aggressive behavior within each of the two 

phenotypes of Z. nevadensis and the significant avoidance and 

aggressive behavior between phenotypes as definite evidence of 

discrimination between disparate hydrocarbon phenotypes (fig. 

2). These agonistic bioassays along with data on distinct hydro­

-carbon patterns and geographic distributions serve as the basis 

for designating two subspecies of Z. nevadensis: Z. n. nevadensis, 

(Hagen) and Z. n. nuttingi (Haverty and Thorne), ssp. nov 

(Haverty and Thorne 1989). 

HYDROCARBONS OF RETICULITERMES 

The morphology of the subterranean termites in the family 

Rhinotermitidae is quite variable among colonies within the 

18 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Figure 2―Agonistic behavior between Zootermopsis hydrocarbon phenotypes I and III: A. Soldier (first Roman numeral) vs. nymphs (second Roman 

numeral) of like or different phenotypes; B. Pseudergates vs. pseudergates; C. Soldier vs. soldier. The number of observations and relative frequency 

of each class of behavior are shown. Behaviors are passive, avoidance, and aggression. 

same species. It is readily acknowledged that the genus 

Reticulitermes is in need of revision. "The definition of the 

various species of Reticulitermes and, therefore, the limits of 

their distributions, is difficult. Certainly this genus is woefully 

in need of a critical taxonomic study..." (Weesner 1970). We 

have characterized the cuticular hydrocarbons of "species" of 

Reticulitermes from the western United States, R. tibialis Banks 

and R. hesperus Banks, as well as those from two species 

common to the eastern United States, R. flavipes (Kollar) and R. 

virginicus (Banks) (fig. 3). Examination of our profiles and 

those published in the literature reveals 80 hydrocarbons from 

these species of Reticulitermes from the southern and western 

United States. Of these hydrocarbons, we consider at least 21 to 

be of diagnostic value (table 2). 

We have collected Reticulitermes in California from areas 

suspected to have only R. hesperus or R. tibialis, Cloverdale and 

Owens Lake, respectively. We found that the cuticular hydrocarbon profiles of workers from these two areas are very similar, 

with the primary difference being one hydrocarbon substitution: 

11, 15-dimethylpentacosane in R. hesperus and 2- or 4-

methylpentacosane in R. tibialis (table 2, fig. 3). This similarity 

of hydrocarbon mixtures indicates that these two collections are 

either the same species or closely related. Our collections of "R. 

tibialis” from two different locations in Arizona, Fairbank and 

Prescott, exhibit extremely different cuticular hydrocarbon profiles which are also different from our collections of either R. 

hesperus or R. tibialis from California (fig. 3). From these 

results we infer that there are probably at least three species of 

Reticulitermes in western North America. 

ORIGIN OF INTRODUCED SPECIES 

Another way to use data on cuticular hydrocarbons is to 

relate the similarity of hydrocarbon profiles to the origin of 

introduced termite species. To test this approach we examined 

the cuticular hydrocarbon profiles of four geographically distant 

populations of the Formosan subterranean termite, Coptotermes 

formosanus Shiraki, in the United States (Haverty and others 

1990). This species is considered to be one of the most voracious 

subterranean termites and a serious threat to wood in structures 

throughout its range. It was introduced into Japan before 1600 

and subsequently into Hawaii and the mainland United States 

(Su and Tamashiro 1987). Although many of the infestations in 

the continental United States were first noticed after 1965, C. 

formosanus colonies were most likely established after World 

War II in the port cities of Houston and Galveston, Texas; New 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 19 
Figure 3―Gas chromatograms of the surface hydrocarbons of four "species" of Reticulitermes. 

Orleans and Lake Charles, Louisiana; and Charleston, South analysis to select discriminating variables (proportion of a given 

Carolina (Beal 1987). There has been a significant "spread" of hydrocarbon), followed by canonical discriminant analysis to 

C. formosanus to other southern port cities including greater provide two-dimensional displays of the chosen variables. GCFort Lauderdale, Florida, Memphis, Tennessee, Baton Rouge, MS analyses of the cuticular wax of representative samples of C. 

Louisiana, and Mobile, Alabama. Similarity or difference in formosanus indicate that all colonies and both castes from all 

hydrocarbon patterns between the four populations (Hallandale, four locations contain the same sixteen hydrocarbon compoFlorida; New Orleans, Louisiana; Lake Charles, Louisiana; and nents. We examined this set of quantitative chemical characters 

Honolulu, Hawaii) was determined by stepwise discriminant to determine the similarity between the hydrocarbon profiles 

20 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Table 2―Diagnostic hydrocarbons for four species of Reticulitermes1 

Reticulitermes species2,3 

Hydrocarbon4 ECL5 flav virg AZ1 AZ2 CA1 CA2 

n-C23 

C25:1 

C25:2 

11,15-DimeC25 

2- or 4-MeC25 

5,17-DimeC25 

C27:1 

C29:2 

C29:1 

C31:2 

11-; 15-MeC31 

11,15-DimeC31 

23.00 +++ ++ +++ o +++ +++ 

24.70 +++ +++ o o o o 

25.40 +++ +++ o o o o 

25.60 o o o o o +++ 

25.70 ++ ++ ++ o +++ o 

25.90 o o ++ o o o 

26.70 o o o +++ o o 

28.69 o o o +++ o o 

28.70 o o o +++ o o 

30.69 o o o +++ o o 

31.40 o +++ o 0 o o 

31.64 o ++ o o o o 

11-; 13-; 15-; 17-MeC33 33.30 o +++ o o o o 

11,15-; 11,21-; 

13,17-DimeC33 33.57 o ++ o o o o 

11-; 13-; 15-; 17-MeC35 35.31 ++ ++ o o ++ o 

11,15-DimeC35 35.60 ++ ++ o o ++ o 

7,17-DimeC35 35.70 + o o o o o 

5,17-DimeC35 35.80 ++ o o o o o 

11-; 13-; 15-; 17-; 

19-MeC37 37.30 ++ ++ ++ o +++ ++ 

11,15-DimeC37 37.59 ++ + o o +++ ++ 

5,17-DimeC37 37.80 ++ o ++ o o o 

1 Hydrocarbons listed for each species are all from chemical analyses by Page, Haverty, and Escoubas. 2

 Reticulitermes "species": flav=R. flavipes, virg=R.virainicus, AZ1=R. tibialis from Fairbank, Ariz., 

AZ2 = R. tibialis from Prescott, Ariz., CA1 = R. hesperus from Cloverdale, Calif., CA2 = R. tibialis from 

Highway 35 near Owens Lake, Calif. 3

 A triple + indicates ≥ 5.0 percent of the total, ++ from 1.0 to 5.0 percent of the total and + from 0.5 to 

1.0 percent of the total hydrocarbon component. Some trace (tr.) components appear infrequently or 

consistently in very small quantities (< 0.5 percent of the total). A zero indicates the hydrocarbon was never 

identified for the phenotype. 4

 Carbon number is the total number of carbons in the parent chain, excluding the methyl groups. 5

 ECL = Equivalent chain length. 

within and among the sampled geographic locations. Our underlying assumption was that colonies of C. formosanus with 

quantitatively similar cuticular hydrocarbon profiles are likely 

to be more closely related, i.e., originating from the same 

geographical source, than those that are less similar. 

Colonies of C. formosanus from each of the four geographic 

locations can be separated from colonies from all of the other 

sites on the basis of concentrations of cuticular hydrocarbon 

components. Discriminant analysis of the proportions of the 

cuticular hydrocarbons of workers identified seven hydrocarbon components that reasonably separate the four populations. 

For the two locations for which we had soldiers, only three 

hydrocarbon components were necessary. No single component, however, can be used to separate C. formosanus from the 

four geographic locations. Stepwise discriminant analysis al- Figure 4―Plot of colonies of C. formosanus from four different locations lowed us to use a selection of the hydrocarbon components to along two axes of canonical discriminant space. Open characters represent 

effectively distinguish C. formosanus from these geographic actual data points; closed characters represent the mean value for the 

locations (fig. 4). population. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 21 
Clearly the population from Lake Charles is very different 

from those from the other locations. This difference supports the 

assertion that the introduction of C. formosanus into Louisiana 

was from two separate sources (La Fage 1987). It also appears 

that the Honolulu population, at least the insects we sampled 

from the Manoa Valley in Honolulu, was probably not the 

original source of infestations in either New Orleans, Lake 

Charles or Hallandale. The affinity of the infestation from 

Hallandale, Florida, is least clear. The hydrocarbon profile is 

significantly different from that of both Honolulu and New 

Orleans. 

Unfortunately, with our present data base, cuticular hydrocarbon profiles have not allowed us to determine whether the 

more recent infestation in Hallandale, Florida, resulted from 

international or domestic, maritime or surface commerce. Our 

results suggest that C. formosanus from Hallandale, Florida, 

New Orleans, Louisiana, and Lake Charles, Louisiana, are not 

related to those from Honolulu, Hawaii, and probably originated 

from other geographical locations. 

CONCLUSIONS 

Our experience, thus far, in applying knowledge of cuticular hydrocarbon composition to the identification of termite 

species has been encouraging. We have used hydrocarbons to 

sort specimens initially to identify a new diagnostic morphological character for Zootermopsis species. Where morphology 

cannot be used to separate hydrocarbon phenotypes, we have 

been able to use inter- and intraphenotype agonistic behavior to 

corroborate cuticular hydrocarbon phenotypes. Geographical 

races of Coptotermes formosanus can be distinguished even on 

the basis of the concentrations of individual hydrocarbon components. 

There are still some unresolved questions to be addressed 

before we consider the use of cuticular hydrocarbons for taxonomic studies of termites. They are: (1) What is the influence of 

genetics and the environment (e.g., temperature, relative humidity, and diet) on the mixture of hydrocarbons? (2) Are cuticular 

hydrocarbons, or the other chemicals present in the wax layer, 

responsible for species or caste recognition? (3) Are hydrocarbon profiles within "good species" qualitatively identical or are 

there some exceptions to the rules; can different biological 

species have identical hydrocarbon profiles? (4) What is the rate 

of change in hydrocarbon profiles as species evolve? Do slight 

differences in profiles mean that the species are closely related? 

and (5) Can hydrocarbons, as well as morphology, behavior and 

genetics, be used to determine phyletic relationships among 

groups within a genus? Resolution of these questions will 

greatly advance the precision of cuticular hydrocarbons as 

chemotaxonomic characters in all insects. 

Currently we rely on gross quantities of chemical insecticides applied to the soil for protection of wooden structures from 

our native subterranean termites. This practice will likely be 

deemed as unacceptable soon. Future species-specific control 

strategies for any subterranean termite will require an understanding of the foraging, feeding, and interspecific behaviors of 

the species to be controlled, and this necessitates accurate 

identification of the species. 

It is readily acknowledged that Reticulitermes is the most 

economically important genus of termites in the United States 

and Europe, yet the genus is in desperate need of revision. There 

should be a significant effort to revise the genus Reticulitermes 

in North America and two important groups of pantropical 

termites: Coptotermes and Nasutitermes. These latter two genera are among the most economically important groups in the 

world. This revision will require collaboration among the termite scientists throughout the world, and will involve studies of 

morphology, behavior, genetics and, of course, cuticular hydrocarbons. We consider cuticular hydrocarbons to constitute a 

very useful set of characters that can provide insight into the 

taxonomy of termites for which classical morphometric analyses have failed. 

ACKNOWLEDGMENTS 

The experiments reported here would not have been possible without numerous collections of termite foraging groups 

and colonies. For their help in gathering the specimens used in 

these studies we thank David Azuma, Patrick Hahn, Jill Haverty, 

Peter Haverty, Jeffery La Fage, Bryce McPherson, Timothy 

Myles, Lori Nelson, William Nutting, Rebecca Rosengaus, 

Michael Rust, Rudolf Scheffrahn, Timothy Schowalter, NanYao Su, and Robin Yamamoto. The diligence of Lori Nelson in 

processing the numerous hydrocarbon samples is greatly appreciated. We are most thankful to Gary Blomquist for helping us 

understand hydrocarbon chemistry and analysis. David Wood 

provided resources to assist in the collection and extraction of 

the western Reticulitermes species described. This work was 

supported, in part, by an Internal Competitive Grant from the 

Pacific Southwest Forest and Range Experiment Station, Forest 

Service, U.S. Department of Agriculture, Berkeley, California, 

and by National Science Foundation grant BSR-8607407 to 

B.L.T., by research scholarships to P.E. from the French government (Programme LAVOISIER), E.I. DuPont de Nemours, Inc., 

and the Philippe Foundation. 

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the continental United States. In: Tamashiro, M.; Su, N.-Y., eds. Biology and 

control of the Formosan subterranean termite. Research Extension Series 

083. Honolulu: University of Hawaii; 48-53. 

Blomquist, Gary J.; Dillwith, Jack W. 1985. Cuticular lipids. In: Kerkut, G.A.; 

Gilbert, L.I., eds. Comprehensive insect physiology, biochemistry and 

pharmacology. Vol. 3. Integument, respiration and circulation. Oxford: 

Pergamon; 117-154. 

Blomquist, Gary J.; Howard, Ralph W.; McDaniel, C.A. 1979. Structure of the 

cuticular hydrocarbons of the termite Zootermopsis angusticollis (Hagen). 

Insect Biochemistry 9:371-374. 

Blomquist, Gary J.; Nelson, Dennis R.; de Renobales, Mertxe. 1987. Chemistry, 

biochemistry, and physiology of insect cuticular lipids. Archives of Insect 

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Broughton, Richard E. 1989. A DNA-DNA hybridization study of the termite 

genus Zootermopsis (Isoptera). Chico: California State Univ.; 77 p. Master 

of Science Thesis. 

Emerson, Alfred E. 1933. A revision of the genera of fossil and recent Termopsinae 

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Scientist 68:546-553. 

Hadley, Neil F. 1985. The adaptive role of lipids in biological systems. New 

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Haverty, Michael I.; Nelson, Lori J.; Page, Marion. 1990. Cuticular hydrocarbons of four populations of Coptotermes formosanus shiraki in the United 

States: similarities and origins of introductions. Journal of Chemical Ecology. 16:1635-1647. 

Haverty, Michael I.; Page, Marion; Blomquist, Gary J. 1989. Value of cuticular 

hydrocarbons for identifying morphologically similar species of pine cone 

beetles. In: Miller, Gordon E., compiler, Proceedings 3rd cone and seed 

insects working party conference, Working party S2.07-01, International 

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Haverty, Michael I.; Page, Marion; Nelson, Lori J.; Blomquist, Gary J. 1988. 

Cuticular hydrocarbons of dampwood termites, Zootermopsis: intra- and 

intercolony variation and potential as taxonomic characters. Journal of 

Chemical Ecology 14: 1035-1058. 

Haverty, Michael I.; Thorne, Barbara L. 1989. Agonistic behavior correlated 

with hydrocarbon phenotypes in dampwood termites, Zootermopsis (Isoptera: 

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Howard, Ralph W.; Blomquist, Gary J. 1982. Chemical ecology and biochemistry of insect hydrocarbons. Annual Review of Entomology 27:149-172. 

Howard, Ralph W.; McDaniel, C.A.; Blomquist, Gary J. 1978. Cuticular 

hydrocarbons of the eastern subterranean termite, Reticulitermes flavipes 

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Howard, Ralph W.; McDaniel, C.A.; Blomquist, Gary J. 1980. Chemical 

mimicry as an integrating mechanism: cuticular hydrocarbons of a termitophile 

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Howard, Ralph W.; McDaniel, C.A.; Nelson, Dennis R.; Blomquist, Gary J.; 

Gelbaum, Leslie T.; Zalkow, Leon H. 1982. Cuticular hydrocarbons of 

Reticulitermes virginicus (Banks) and their role as potential species- and 

caste-recognition cues. Journal of Chemical Ecology 8:1227-1239. 

Howard, Ralph W.; Thorne, Barbara L.; Levings, Sally C.; McDaniel, C.A. 

1988. Cuticular hydrocarbons as chemotaxonomic characters for Nasutitermes 

corniger (Motschulsky) and N. ephratae (Holmgren)(Isoptera: Termitidae). 

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Korman, Amy K.; Pashley, Dorothy P.; Haverty, Michael I.; La Fage, Jeffery P. 

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Zootermopsis species (Isoptera: Termopsidae). Annals of Entomological 

Society of America 84:1-9. 

La Fage, Jeffery P. 1987. Practical considerations of the Formosan subterranean 

termite in Louisiana: A 30-year-old problem. In: Tamashiro, M.; Su, N: Y., 

eds. Biology and control of the Formosan subterranean termite. Research 

Extension Series 083. Honolulu: University of Hawaii; 37-42. 

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F.M., eds. Biology of termites, Vol. I. New York: Academic Press; 407-432. 

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Zootermopsis species (Isoptera: Termopsidae) based on a mandibular character of non-soldier castes. Annals of the Entomological Society of America 

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477-525. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 23 
An Assessment of the Potential Uses of Agonistic Behaviors 

in Termite Control1 

Barbara L. Thorne Michael I. Haverty2 

Abstract: The potential use of termite-termite agonism in pest 

control is explored and evaluated. Intra- and interspecific encounters among termites from different colonies are known to 

result in aggressive or avoidance behaviors in a variety of 

species. Recent studies suggest, however, that intraspecific 

confrontations only rarely evoke aggressive responses in several 

economically important termite genera in the United States 

(Coptotermes, Reticulitermes, and Zootermopsis). Thus the 

most promising applied use of natural agonistic behaviors among 

termites appears to be in research on individual- and colonyrecognition systems in the Isoptera. Artificial manipulation of 

recognition and response cues might facilitate novel control 

methodologies based on masking or interfering with natural 

stimuli. Directions for future research are discussed. 

Insect behaviors are diverse, and knowledge of the behaviors of a species has always been a key element in pest management. Basic knowledge of activity periods, diet preferences, and 

mating behaviors can be central in determining an approach 

toward deterring a pest species. Taking advantage of behavioral 

patterns or interfering with natural repertoires or both can 

produce very effective control methodologies. 

Understanding the foraging behavior of subterranean termites is crucial to prevention of damage to buildings (Beal and 

others 1989; Su and Scheffrahn 1990). Preventative techniques 

include proper construction practices to exclude or deter foraging and feeding by subterranean termites and application of large 

volumes of chemical insecticides as soil drenches to kill or repel 

foraging subterranean termites. Existing and future methods for 

remedial control of subterranean termites will also rely on 

knowledge of the foraging behavior of these insects (Su and 

Scheffrahn 1990). 

Two promising future control methods involve the use of 

physical barriers and the use of nonrepellent, slow-acting insecticides. Physical barriers will consist of a substrate that has a 

particle size impenetrable to subterranean termites (Su and 

Scheffrahn 1990). Nonrepellent, slow-acting insecticides will 

be used in baits or in baiting systems. Subterranean termites will 

recruit to the bait stations through natural foraging behaviors and 

feed on the chemically impregnated wood. It is then hoped that 

1

Presented at the Symposium on Current Research on Wood-Destroying 

Organisms and Future Prospects for Protecting Wood in Use, September 13, 

1989, Bend, Oregon. 2

Senior Research Associate and Adjunct Assistant Professor, Department 

of Biology, Northeastern University, Boston, Mass. 02115 and Curatorial 

Research Associate, Museum of Comparative Zoology, Harvard University, 

Cambridge, Mass. 02138; Project Leader and Principal Research Entomologist, 

Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. 

Department of Agriculture, P.O. Box 245, Berkeley, Calif. 94701 

they will return to their colony and feed their insecticide-laced 

crop contents to colony mates before dying. Normal foraging 

behaviors will thus cause an entire colony to be slowly poisoned 

by toxic baits. Termite colony populations will become depressed, and they will ultimately be eliminated, not simply 

excluded, from structures. 

Another behavior that has recently received attention by 

termite biologists is agonistic behavior. Agonistic behavior 

involves social interactions between individuals, including submitting, fleeing and fighting, even to death. Termites show a 

wide range of agonistic behaviors when interacting with termites from a different colony. In all cases studied to date, 

termites from colonies of different sympatric species respond 

aggressively when they meet (Adams and Levings 1987; Clément 

1982; Grassi and Sandias 1896-1897; Haverty and Thorne 1989; 

Ne11968; Springhetti and Amorelli 1982; Thorne 1982; Traniello 

and Beshers 1985). Intraspecific confrontations also result in 

clear aggressive or avoidance behaviors in a variety of termite 

species (Adams and Levings 1987; Andrews 1911; Binder 1988; 

Clément 1986; Dudley and Beaumont 1889; Howick and 

Creffield 1980; Jones 1987; Levings and Adams 1984; Nel 

1968; Pearce and others 1990; Pickens 1934; Su and Haverty 

1991; Thorne 1982). Since many of these termite-termite interactions result in injury or death to some or all of the insects, it is 

reasonable to evaluate their potential use in control of termites 

as structural pests. 

CASE STUDY: THE DAMPWOOD TERMITE GENUS 

Zootermopsis 

From an individual termite's viewpoint, the fundamental 

problem in encounters with other termites is the correct discrimination of colony mates from noncolony mates. We examined 

intra- and interspecific interactions among all species of 

Zootermopsis Emerson in the Pacific coastal states and southwest deserts of the United States (Haverty and Thorne 1989). 

Those results are summarized here, and new data on response of 

naive soldiers from incipient colonies are reported. 

Zootermopsis laticeps (Banks) is morphologically distinct 

from other members of the genus. This species also has an 

isolated geographic range in Arizona, New Mexico, and northern Mexico, and lives in dead portions of live trees, usually in 

riparian situations. In the absence of alates, the morphological 

characters used to differentiate the described species Z. 

angusticollis (Hagen) and Z. nevadensis (Hagen) were ambiguous. That imprecision made it impossible to establish valid 

experimental encounters between colonies. This problem was 

resolved when Haverty and others (1988) discovered three 

consistent and distinct cuticular hydrocarbon phenotypes among 

the two "species," Z. angusticollis and Z. nevadensis, that occur 

24 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
along the Pacific Coast. The hydrocarbon separations enabled us 

to isolate a diagnostic character, shape and position of the 

subsidiary tooth on the right mandible of nonsoldiers, which 

established unambiguous discrimination of Z. angusticollis 

from Z. nevadensis (Thorne and Haverty 1989). 

Z. angusticollis shows one distinct hydrocarbon profile 

throughout its range (labelled phenotype II by Haverty and 

others [1988]). Two hydrocarbon phenotypes (I and III) are 

associated with the single morphological species Z. nevadensis, 

but each chemical phenotype has a discrete geographic distribution and may have temporal isolation in alate phenologies 

(Haverty and others 1988; Haverty and Thorne 1989; Thorne 

and Haverty 1989; Weesner 1970). In our experiments we 

investigated whether intra- or inter-hydrocarbon phenotypes of 

Zootermopsis colonies show discrimination in behavioral encounters. 

In the laboratory we set up pairwise experimental trials in 

which we placed combinations of various castes from different 

hydrocarbon phenotypes into petri dish arenas lined with filter 

paper. Responses were recorded on a ranking system from no 

noticeable reaction to immediate lethal attack. Observed behaviors were typically either docile or highly aggressive, with little 

intermediate response. 

General results of these experiments are summarized here 

(for more detail see Haverty and Thorne 1989). In intraphenotype 

pairings, agonistic reactions among members of any castes are 

rare, except between some colonies of Z. angusticollis. 

Interphenotype interactions frequently stimulate aggressive responses (fig. 1), but behaviors vary depending on which colonies 

are involved. Z. angusticollis and Z. nevadensis phenotype III, 

which occur sympatrically throughout much of their range, are 

more aggressive towards each other than are Z. angusticollis and 

Z. nevadensis phenotype I, which have an allopatric distribution. The two hydrocarbon phenotypes of Z. nevadensis do show 

discrimination responses in behavioral encounters, and in that 

way act like distinct species. The behavioral discrimination was 

further evidence to justify designation of the Z. nevadensis 

complex into two subspecies, Z. nevadensis, subsp. nevadensis 

(Hagen) [phenotype I] and Z. nevadensis subsp. nuttingi (Haverty 

and Thorne) [phenotype III] (Haverty and Thorne 1989). 

Supplementing experiments reported in Haverty and Thorne 

(1989), we have recently conducted a series of comparable trials 

involving young, naive soldiers from experimentally bred laboratory colonies. In July and August 1987, the wings of mature 

male and female Z. nevadensis subsp. nuttingi alates from a 

variety of colonies were removed and the alates were paired in 

small petri dishes lined with moist sand and containing a piece 

of Douglas-fir wood. Many of these couples successfully reared 

offspring. The first soldier differentiated when brood size reached 

approximately 15-20 individuals. In March 1989 we removed 

these young soldiers from incipient colonies which still contained both primary reproductives, and introduced each soldier 

to three nymphs or larvae from a haphazardly selected colony 

of Z. nevadensis subsp. nevadensis [14 trials] or Z. angusticollis 

Figure 1―Zootermopsis angusticollis soldier attacking a Z. nevadensis nymph. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 25 
[10 trials]. Each soldier was used only once (experimental 

protocol identical to that described for Haverty and Thorne 

1989, Experiment 1). In the Z. nevadensis subsp. nuttingi versus 

Z. nevadensis subsp. nevadensis encounters, naive Z. n. subsp. 

nuttingi soldiers attacked and killed Z. n. subsp. nevadensis 

larvae or nymphs in 5 of the 14 trials. In all 14 cases soldiers 

showed agonistic responses by repeatedly flaring their mandibles. Results of the Z. nevadensis subsp. nuttingi soldier 

encounters with Z. angusticollis larvae or nymphs were consistent: in each of the 10 cases the soldiers attacked and killed the 

Z. angusticollis. These data on naive soldiers parallel results 

from the experiments using soldiers from mature field colonies 

reported in Haverty and Thorne (1989). 

The generally docile reactions observed in the intraphenotype 

trials raised the possibility that passive fusion might occur 

between members of two conspecific field colonies whose 

gallery networks met in a host log. We have demonstrated 

experimentally, however, that soldiers, nymphs, and pseudergates 

will kill and consume functional reproductives from a foreign 

colony, even within the same hydrocarbon phenotype. Thus, 

complete colony fusion in nature is unlikely (Haverty and 

Thorne 1989). Aside from Zootermopsis, the only cases of 

passive coalescence of termite colonies reported in the literature 

involve Reticulitermes (Rhinotermitidae) (Clement 1986; Jones 

1987) and some populations of Coptotermes (Rhinotermitidae) 

(Su and Haverty 1991; Su and Scheffrahn 1988). 

The stimuli responsible for aggressive behaviors in 

Zootermopsis or other species of North American termites are 

unknown. Clearly, however, the rapidity, consistency, and efficiency of these aggressive responses are effective in termitetermite interactions. In the remainder of this paper we examine 

realistic potential uses of these natural behaviors as elements of 

pest management strategies. 

POTENTIAL APPLIED USES OF TERMITE AGONISTIC 

BEHAVIORS 

Natural aggressive behaviors between termite colonies 

might be used constructively either in bioassays to learn more 

about the biology of a particular species or directly in termite 

control. As an example, in species showing consistent intraspecific aggression, agonistic behaviors could be used to precisely 

map the foraging territory of a given colony (technique used by 

Pearce and others 1990). Termites from different locations 

could be observed in encounters with (A) individuals known to 

be from the focal colony and (B) members of a geographically 

distinct, conspecific colony. A passive response to sample A and 

an aggressive response to B would suggest that termites in the 

test sample were foragers from the same colony represented in 

sample A (but responses of termites to neighbors versus strangers has not yet been studied [see Gordon 1989]). An agonistic 

response to both groups A and B would mean that the termites 

in the test sample were from a separate (third) colony. 

Precise knowledge of the foraging areas of a termite colony 

would be useful in studies of colony population size, growth 

rate, foraging range, and the density of colonies within a community. In treatment procedures, knowledge of foraging areas 

may become crucial as control techniques using bait toxicants 

are developed. Unfortunately, use of agonistic bioassays in 

mapping colony foraging areas will not work reliably on any of 

the two dominant genera of subterranean termite pests in the 

United States Reticulitermes and Coptotermes), because intraspecific mixtures of these termites are generally docile. 

(Broad variability in degree of agonistic response among termites from different colonies or populations or both has been 

noted by Haverty and Thorne 1989; Su and Haverty 1991; Su 

and Scheffrahn 1988; Thorne 1982.) 

Perhaps the most promising and intriguing outcome of the 

study of termite agonistic behaviors is that such work might 

ultimately lead to an understanding of the recognition code(s) 

used by termites to discriminate colony mates from noncolony 

mates. Recognition may involve cuticular hydrocarbon components (Howard and Blomquist 1982; Howard and others 1980, 

1982); other behavioral and chemical cues are likely involved as 

well. Once the discrimination process is understood, numerous 

applied approaches could be designed around the theme of 

masking or interfering with recognition stimuli. Manipulation of 

recognition and response cues could be used to enable chemically loaded intruders to enter a colony, to potentially instigate 

a civil war, or to impregnate building materials with an offensive, behavioral stimulus to prevent termite colonization. 

Very generally, any stimulus that aggravates termites is 

potentially useful in termite control. The scientific goal is to find 

a stimulus that repels termites, or triggers an avoidance response, but it must be a persistent avoidance or repulsion 

stimulus with little or no habituation. If the termites acclimate to 

the stimulus, it will no longer elicit the desired response. 

Control applications involving behavioral bioassays or live 

termites as an integral part of the pest management program will 

require trained operators and, typically, a longer treatment 

period than with chemical applications. Expense is predicted to 

be higher because of the labor involved in culturing and sampling termites. Integrated approaches may be beneficial in a 

variety of circumstances. However, in cases where little or no 

pesticides are desired in the infested area, control methodologies 

which make use of natural behavioral repertoires may provide 

effective alternatives. 

DIRECTIONS FOR FUTURE RESEARCH 

Studies of Additional Taxa 

Further studies on patterns of agonistic behavior within and 

among termite species will broaden our perspective on the 

potential uses of such aggressive or repulsive responses in 

termite control. Thus far, agonistic behaviors within and between Zootermopsis species have been studied (Haverty and 

Thorne 1989). Intraspecific agonism has been studied in 

Heterotermes aureus (Snyder) (Binder 1988; Jones 1987) and 

Coptotermes formosanus shiraki (Su and Haverty 1991). The 

genus Reticulitermes is the most economically important group 

of wood-destroying insects in the United States, yet little behavioral work has been done on the Reticulitermes species within 

the United States. This genus should definitely be the target of 

26 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
future research on intra- and interspecific agonistic behavior. 

Chemoreception 

The neurobiology of chemoreception has never been examined in termites, but this approach should be tractable and could 

help, for example, in our understanding of the role of cuticular 

hydrocarbons (or fractions of these lipids) in termite-termite 

recognition processes. Such studies would help us identify 

natural, biologically active compounds with potential for practical applications. 

Detailed Ethological Analyses 

Many of the behaviors between termites of different colonies may be more subtle than overt aggression, avoidance, or 

apparent tolerance. Fine scale ethological studies of intercolony 

interactions must be done to investigate the spectrum between 

fighting and "passive" responses, and isolate the stimuli evoking 

each category of response. 

Evaluation of Experimental Methodologies 

Laboratory results should be confirmed in the field to 

validate the experimental protocols used to study dynamics 

between termite colonies. When intra- or interspecific encounters occur between termites in their natural social and physical 

environment, does one observe the same passive or aggressive 

reactions which are seen in laboratory trials involving small 

subsets of the same two colonies? 

The methods for studying termite-termite encounters are 

still being devised and refined. Binder (1988) introduced some 

innovative approaches in his study of H. aureus. In one experiment he simulated a foraging arena with a balsawood barrier 

separating termites from separate colonies (dyed to differentiate colony affiliation). A high magnification video camera was 

used to document movements and behaviors over the 24 hours 

required for the termites to penetrate the barrier. Similar studies 

employing video equipment and image tracking software would 

expand our understanding of termite-termite behaviors. Eventually, standardization of protocols should be considered to facilitate comparisons between studies on related taxa. 

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USDA Forest Service Gen. Tech. Report PSW-128. 1991. 27 
Factors Affecting the Tunneling Behavior of the Western 

Subterranean Termite, Reticulitermes hesperus Banks1 

James L. Smith Michael K. Rust2 

Abstract: Laboratory studies were conducted to 

determine factors that affect the tunneling 

behavior of the western subterranean termite 

(Reticulitermes hesperus Banks). Soil particle 

sizes between 2.36 and 0.84 mm prevented 

tunneling. Exposure to solid layers of calcium, 

magnesium, or zinc borate did not repel workers, 

but produced >87 percent kill within 10 d. No 

tunneling occurred in soils treated with the 

formulated termiticides tested at concentrations 

≥50 ppm. Termites did not tunnel in soils 

treated with as little as 1 ppm bifenthrin or 

cypermethrin. Exposure to bifenthrin and 

cypermethrin deposits immobilized termite workers 

which prevented them from tunneling. 

Termites failed to penetrate a layer of 

dead termites killed by earlier exposure to 

chlorpyrifos. Contact with dead termites 

resulted in 96 percent mortality of the tunneling 

workers. Workers readily penetrated layers of 

termites freshly killed by freezing, and some 

died within 24 h. 

At 15°C, the distance tunneled by 

acclimated termites was significantly greater 

than those of unacclimated termites. At 21-32°C, 

the acclimation period did not affect the 

distance tunneled. Tunneling rates were 

significantly lower at 15°C than at 21, 27, or 

32°C. Tunneling rates at 27°C were significantly 

greater than at 21 or 32°C. 

Most species of subterranean termites live 

deep within the soil, requiring workers to 

construct elaborate systems of tunnels to forage 

for food and water. The competence of a 

structural subterranean termite pest may, to a 

1 Presented at the Symposium on Current 

Research on Wood-Destroying Organisms and 

Future Prospects for Protecting Wood in Use, 

September 13, 1929, Bend, Oregon. 2 Graduate Research Assistant and 

Professor of Entomology, respectively, University 

of California, Riverside, Calif. 

great extent, be determined by its foraging 

behavior. Williams (1977) categorizes foraging 

in subterranean termites into two basic patterns: 

species which forage over a long distance to 

larger, more scattered pieces of litter and 

species which forage close to the nest, consuming 

small pieces of litter. Reticulitermes spp. in 

the western United States clearly fall into the 

first category. 

The habit of random foraging may be a 

distinct advantage for Amitermes, Heterotermes, 

and Reticulitermes spp. occurring in open areas 

or in ranges of dense but widespread vegetation 

types. Studies by Su and others (1984) suggest 

that the Formosan subterranean termite 

(Coptotermes formosanus Shiraki) forages in a 

random network of tunnels. Within small plots, 

Heterotermes aureus (Snyder) was a random forager 

(Jones and others 1987). Descriptions of 

tunneling in the western subterranean termite 

(Reticulitermes hesperus Banks) of irregular 

reticulations with no particular plan also 

suggest a random foraging pattern (Pickens 1934). 

Studies were conducted to determine various 

abiotic and biotic factors that might affect the 

random tunneling behavior of R. hesperus. The 

effects of soil particle size, borate compounds, 

soil treated with termiticides, the presence of 

dead termites, and temperature on tunneling 

behavior were studied. 

METHODS AND MATERIALS 

Size of Soil Particles 

To determine the optimal particle size, 

termites were allowed to tunnel in soils with 

various particle sizes. Glass tubes (9 mm i.d. 

by 15 cm tall) were filled with soil with 

particle sizes ranging from 2.36 to 0.84, 0.84 to 

0.42, 0.42 to 0.25, 0.25 to 0.18, and 0.18 to 

0.15 mm (8 to 20, 20 to 40, 40 to 60, 60 to 80, 

and 80 to 100 mesh/in.). Twenty R. hesperus 

workers were placed in the bottom of each of five 

tubes for each range of particle sizes. The 

distance tunneled by the termites was recorded 

periodically for 24 h (Smith and Rust in press). 

28 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Influence of Borate Barriers on Tunneling 

Termites were allowed to tunnel in glass 

tubes packed with a band of solid inorganic 

borate to determine its effect on their tunneling 

behavior. Calcium, magnesium, and zinc borate 

powders (provided by U.S. Borax Research, 

Anaheim, CA) were used in the study. The bottoms 

of glass tubes (9 mm i.d. by 15 cm tall) were 

closed with a cotton plug (1.8 cm long) and 

filled with 3.9 cm of untreated soil (20-100 

mesh), a 1-cm thick layer of borate compound, and 

6.5 cm of untreated soil. Cotton plugs (1.8 cm 

long) were placed in the top of each tube. The 

tubes were inverted, the cotton plugs were 

removed from the bottom, and 1.5-ml aliquots of 

water were added to the soils. This prevented 

the 3.9-cm untreated layer of soil from being 

contaminated with borate and termites from 

encountering any borate before the 1-cm layer. 

Twenty workers were placed in the bottom of each 

tube along with a small piece of paper towel to 

serve as food. The tubes were stoppered and set 

upright. Termites were allowed to tunnel for 48 

h. The number of tubes in which termites 

penetrated the borate barrier and number of dead 

termites were counted at 48 h. Termites were 

removed from the tubes and placed in plastic 

Petri dishes (35 mm diameter by 10 mm tall) 

provisioned with a disk of clean paper towel. 

The dishes and termites were maintained at 25 + 

2°C and 93 percent RH. The number of dead 

termites was counted 7 and 10 days after the 

termites were removed from the tunneling tubes. 

Five replicates were used for each of the three 

different borate compounds. 

Influence of Soil Termiticides on Tunneling 

To determine the toxicity and repellency of 

soils treated with termiticides, termites were 

permitted to tunnel in glass tubes (9 mm i.d. by 

15 cm tall) packed with untreated and treated 

soil (Smith and Rust in press). A 3.9-cm layer 

of untreated soil was gently packed into each 

tube followed by a 7.5-cm layer of treated soil. 

The tubes were inverted and 1.5-ml aliquots of 

water were added to the untreated soil. The 

water was drawn through the treated section with 

an air vacuum, allowing the soil to be uniformly 

moistened with minimal contamination of the 

untreated soils. 

Twenty workers were introduced in the 

bottom of each tube. The distance tunneled by 

the termites was recorded after 48 h, at which 

time the termites were removed from the tubes and 

the number of moribund and dead insects was 

counted. 

Avoidance of Dead Termites 

To determine the effect of dead termites on 

the tunneling behavior of R. hesperus, termites 

were allowed to tunnel in soil and encounter dead 

termites. Glass tubes (9 mm i.d. by 15 cm tall) 

were filled with 3.9 cm of soil at the bottom. 

Next, a layer of ten dead termites was added, 

which had been exposed to either soil treated 

with chlorpyrifos at 500 ppm for 24 h (Smith and 

Rust in press) or frozen for 24 h. Exposure to 

treated soil simulates mortality caused by 

contact with a chemical barrier, and freezing 

simulates natural mortality. The dead termites 

were covered with 7.5 cm of soil. Twenty live 

workers were added to the bottom of each of five 

tubes per treatment and allowed to tunnel 24 h. 

At 24 h, the number of tubes in which the 

termites penetrated the barrier of dead termites 

and the number of termites rendered dead or 

moribund during the tunneling activities were 

recorded. 

Influence of Temperature on Tunneling 

Studies were conducted to determine whether 

length of acclimation of termites to certain 

temperatures affected their rate of tunneling. 

To determine whether acclimation periods were 

important, 5 lots of 20 termites were held at 15, 

21, 27, or 32°C or at room conditions (25°C) for 

either 12, 24, 36, or 48 h before testing. Glass 

tubes (9 mm i.d. by 15 cm tall) were filled with 

11.4 cm of untreated soil. The soil was 

moistened with 1.5 ml of water. The tubes were 

placed in environmental chambers maintained at 

either 15, 21, 27, or 32°C for 12 h to condition 

the soil to the appropriate temperature. At the 

end of each termite acclimation period, twenty 

workers were placed in each of five tubes per 

temperature and allowed to tunnel for 12 h. The 

five tubes with acclimated termites and termites 

held at 25°C were placed back into the same 

acclimation chambers maintained at either 15, 21, 

27 or 32°C. Distances tunneled were recorded at 

12 h. Differences in the distances tunneled from 

each acclimation period and temperature were 

analyzed by an analysis of variance (ANOVA) using 

MSTAT: Micro Computer Statistical Program 

(Michigan State University, East Lansing), and 

means were separated by Tukey's HSD at the alpha 

= 0.05 level (Tukey 1953). 

To determine the effect of soil temperature 

on tunneling rates, workers were permitted to 

tunnel in glass tubes (9 mm i.d. by 30 cm tall) 

filled with 25 cm of untreated soil and moistened 

with 3 ml of water. Groups of termites were 

acclimated at 15, 21, 27, and 32°C for 48 h. The 

tubes containing the moist soil were placed in 

environmental chambers maintained at either 15, 

21, 27, or 32°C and allowed to condition for 

12 h. After the 48-h acclimation period, twenty 

workers were placed in each of five tubes per 

temperature. The five tubes with termites were 

placed back at the original four acclimation 

temperatures. Distances tunneled were recorded 

at 2, 4, 6, 8, 10, 12, and 24 h. Tunneling rates 

at the four temperatures were determined by 

regression analysis of variance using MSTAT: 

Micro Computer Statistical Program (Michigan 

State University, East Lansing). 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 29 
RESULTS AND DISCUSSION 

Size of Soil Particles 

Rates of termite tunneling in tubes 

filled with soils of different particle sizes 

were as follows: 

Particle Distance tunneled Rate ± 95pct 

size (mm) Total cm (h)a CLb (cm/h) 

2.36-0.84 0 0 

0.84-0.42 24.9 (115) 0.22 ± 0.09 

0.42-0.25 32.5 (115) 0.28 ± 0.11 

0.25-0.18 28.8 (100) 0.29 ± 0.13 

0.18-0.15 30.3 (100) 0.30 ± 0.21 

a Total distance tunneled in (total 

cumulative hours) b Mean rate with 95 pct confidence level in 

cm/hr 

Consequently, soil with particle sizes ≥0.15 and 

≤0.84 mm were used in subsequent studies to 

ensure optimal tunneling activity. 

Size of the substrate particles is 

important in determining whether subterranean 

termites can tunnel through soil. Ebeling and 

Pence (1957) showed that soil with particle sizes 

ranging from 3.35 to 1.18 mm (6-16 mesh/in.) were 

impenetrable to R. hesperus, and soil with 

particle sizes ranging from 0.3 to 0.15 mm (50-

100 mesh/in.) were penetrable. For the Formosan 

subterranean termite, C. formosanus, it was 

determined that penetration occurred in untreated 

substrates with particle sizes ranging from 0.8 

mm to <0.2 mm (20 to 80+ mesh/in.); particle 

sizes from 2.4 to 1.7 mm (8-12 mesh/in.) 

completely prevented penetration (Tamashiro and 

others 1987). 

Substrates with particle sizes ≥ 3 mm were 

easily penetrated by the subterranean termites 

studied thus far; termites were able to move 

through the spaces made by these larger particles 

(Ebeling and Pence 1957, Tamashiro and others 

1987). Soils that are impenetrable to termites 

have particles that are too large for termites to 

pick up in their mouths and move, yet with spaces 

between particles small enough so that termite 

headcapsules will not pass through. The size of 

particles that are penetrable to termites will 

vary with each species. 

Influence of Borate Barriers on Tunneling 

R. hesperus workers penetrated 60 percent 

of the calcium borate barriers and 100 percent of 

the magnesium borate and zinc borate barriers. 

There was 42 percent mortality of termites 

exposed to calcium borate barriers at 48 h, but 

no substantial mortality with the other two 

barriers. Termite mortality was 87, 98, and 89 

percent in tubes packed with calcium, magnesium, 

and zinc borates, respectively, 10 d after 

removal from the tubes. The solid borate layers 

were not repellent to worker termites, and 

contact with or ingestion of them caused 

significant latent mortality. 

Influence of Soil Termiticides on Tunneling 

As shown in figure 1, termites did not 

tunnel into soil treated with bifenthrin or 

cypermethrin, regardless of concentration. No 

tunneling occurred in soil treated with 

chlordane, chlorpyrifos, fenvalerate, isofenphos, 

or permethrin at concentrations ≥50 ppm. In 

addition to preventing tunneling into treated 

soil, the above soil termiticide treatments also 

severely reduced tunneling activity in the 

untreated zone beneath the treated soil (fig. 1). 

Termites tunneled in soil treated with chlordane, 

chlorpyrifos, isofenphos, fenvalerate, or 

permethrin at concentrations ≤10 ppm. The most 

tunneling occurred in soils treated with 

chlorpyrifos and isofenphos, whereas very little 

tunneling occurred in the soils treated with 

chlordane, fenvalerate, or permethrin at these 

lower concentrations (fig. 1). After 48 h, 

termites were removed from the soil-filled tubes. 

The greatest mortality (76 to 100 percent) 

occurred in the tubes filled with soils treated 

with 100 to 500 ppm of bifenthrin or chlorpyrifos 

(table 1). 

Termites did not tunnel in treated soil, 

especially in soil treated at high 

concentrations, yet substantial mortality 

occurred. Insecticide diffused from treated to 

untreated soil in concentrations high enough to 

kill or affect behavior. Movement of insecticide 

seems to be facilitated by water solubility or 

vapor pressure. Chlordane appeared to move the 

least distance, while bifenthrin and cypermethrin 

moved the farthest, because termites tunneled 

closest to soil treated with chlordane and never 

Figure 1--Average distance tunneled by R. 

hesperus underneath treated soils and in soils 

treated at 500 to 1 ppm with various termiticides. Dashed lines indicate common boundary of 

treated and untreated soil. Vertical bars 

represent standard errors of means. Chlorp. = 

chlorpyrifos, Isofen. = isofenphos, Bifen = 

bifenthrin, Cyper. = cypermethrin, Fenval. = 

fenvalerate, Perm. = permethrin, c = control 

(Smith and Rust in press). 

30 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
----------------------------------- 

Table 1--Percent mortality of R. hesperus after 

tunneling 48 h in tubes filled with termiticidetreated soils. 1 

Concentration of termiticide (ppm) 

Termiticide 500 250 10 50 10 1 

Bifenthrin 100 100 76 29 2 9 

Chlorpyrifos 90 95 85 51 10 42 

Cypermethrin 50 27 1 5 0 44 

Fenvalerate 32 4 52 0 0 2 

Isofenphos 26 39 42 40 0 40 

Chlordane 22 20 4 2 19 21 

Permethrin 4 6 1 3 3 3 

1 Adapted from Smith and Rust (in press). 

approached the soil treated with bifenthrin or 

cypermethrin (fig. 1). Apparently chlordane is 

not as repellent as bifenthrin and cypermethrin. 

At high concentrations less mortality occurred in 

soils under chlordane-treated soil than in soils 

under the bifenthrin and cypermethrin treatments, 

even though termite tunneling was severely 

reduced. This suggests that biologically active 

amounts of bifenthrin and cypermethrin were 

moving longer distances. At low concentrations, 

no significant mortality was produced underneath 

bifenthrin and cypermethrin treatments, and very 

little tunneling was observed in the untreated 

soil. 

We hypothesize that the alpha-cyano 

pyrethroids produced sublethal effects which may 

inhibit tunneling, perhaps by temporarily 

paralyzing termites that contact them. Scott and 

Matsumura (1983) reported two types of pyrethroid 

action against cockroaches. Type I action was 

related to a factor which causes repetitive 

neuronal discharges, whereas type II action was 

related to suppressing repetitive discharge and 

causing immobility. The presence of an alpha-, 

may lead to type II action. Some pyrethroids 

with and without alpha-cyano moieties, such astype I and type II action (Scott and Matsumura 

1983). This might explain why there was more 

tunneling in or underneath soils treated with 

fenvalerate and permethrin than there was 

underneath soil treated with bifenthrin or 

cypermethrin. 

Factors causing repellency of termites to 

soils treated with insecticide are unclear. Su 

and others (1982) classified insecticides as type 

I or type II, according to behavioral responses 

of C. formosanus. Type I insecticides (e.g., 

pyrethroids) killed very few termites because the 

termites sealed or avoided tunnels that extended 

to treated areas, and therefore were considered 

repellent. Type II insecticide treatments (e.g., 

chlordane and chlorpyrifos) also killed few 

termites, but survivors avoided the treatment as 

dead and decaying termites accumulated in the 

tunnels, not in response to insecticide-treated 

media. Consequently, type II insecticides were 

not considered repellent. 

In our studies with R. hesperus fenvalerate 

and permethrin performed like type I 

insecticides, killing very few termites and 

preventing tunneling in treated soil. The 

pyrethroids bifenthrin and cypermethrin, however, 

provided very different effects. They prevented 

tunneling by immobilizing the insects. 

Chlordane-treated soils performed as a type I 

insecticide, and chlorpyrifos did not elicit 

type I or type II responses. Termites tunneled 

into soils beneath the chlorpyrifos treatment, 

resulting in high mortality, but did not tunnel 

into the treated soil. 

When soils were treated with high 

concentrations of all these termiticides, the 

amount of tunneling was negligible. Some 

tunneling occurred when soils were treated with 

lower concentrations. Biologically active 

amounts of insecticide move from the upper layers 

of treated soil to untreated soils below, causing 

reduced tunneling, mortality, and sublethal 

effects. This downward movement may increase the 

effective depth of the primarily surface 

applications of insecticides. Even though 

environmental exposure may reduce the initial 

levels (500 ppm) of soil treatments, it is likely 

that the soils will retain their repellency for a 

number of years. There is a considerable amount 

of research yet to be conducted on the factors 

that affect longevity and movement of insecticide 

in the soil, as well as the behavior of termites 

encountering these termiticide-treated soils. 

Avoidance of Dead Termites 

Workers of R. hesperus did not penetrate 

the layer of dead termites which were killed by 

exposure to chlorpyrifos, and there was 96 

percent mortality from their tunneling efforts. 

Termites penetrated the layer of termites killed 

by freezing in 80 percent of the tubes and there 

was 30 percent mortality. In the untreated 

controls, workers tunneled to the top of all the 

tubes with only 5 percent mortality. The layer 

of termites killed with chlorpyrifos was not 

penetrated by R. hesperus workers; contact with 

the treated termites was enough to kill 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 31 
significant numbers of termites within 24 h. The 

layer of "naturally" killed termites was not 

completely repellent to tunneling termites, but 

did produce some mortality. The appearance of 

dead and decaying termites may lead to the 

avoidance of treated areas as suggested by Su and 

others (1982). However, it may also be that 

toxicant on the dead termites also contributes to 

avoidance behavior in addition to mortality. 

Influence of Temperature on Tunneling 

Regardless of acclimation periods, the 

tunneling rates of termites exposed to soil 

temperatures of 21, 27, and 32°C were not 

significantly different from the tunneling rates 

of unacclimated termites at these same 

temperatures. At 15°C, the distance tunneled by 

termites acclimated for 12, 24, 36, or 48 h was 

significantly greater than those tunneled by 

unacclimated termites (fig. 2). 

Figure 2--Average distance tunneled by R. 

hesperus at four different temperatures and five 

acclimation periods. Circle = 15.6°C, square = 

21.1°C, star = 26.7°C, triangle = 32.2°C. 

At 15°C, termite tunneling rates (0.1 cm/h) 

were significantly less than at 21, 27, or 32°C 

(F = 17.65; df = 3; P < 0.01). At 21 and 32°C, 

there were no significant differences in termite 

tunneling rates (0.39 and 0.33 cm/h, respectively). Tunneling rates at 27°C were 

significantly greater than at 15 and 21°C (F = 

70.58; df = 2; P < 0.01) (fig. 3). 

As termites forage from subterranean 

galleries where soil temperatures are relatively 

constant, worker termites will be exposed to 

elevated temperatures. The rates at which they 

tunnel will influence the time spent contacting 

treated soils and the time exposed to elevated 

and possibly lethal temperatures. The study 

suggests that termites leaving subterranean 

galleries do not require acclimation to the 

elevated surface temperatures, whereas returning 

termites may require time to acclimate to cooler 

subterranean conditions. 

The above studies show that both abiotic 

and biotic factors affect the tunneling behavior 

of R. hesperus. Certain physical and chemical 

barriers have the ability to affect tunneling 

behavior most drastically. The potential effects 

of biotic factors such as temperature and of the 

appearance of dead termites in galleries on the 

performance of chemical barriers are evident but 

need further examination. 

Figure 3--Regression lines of distance tunneled 

by R. hesperus at four different temperatures. 

15.6°C, y = 0.44 + 0.10x; 21.1°C, y = 1.46 + 

0.39x; 26.7°C, y = 2.21 + 0.49x; 32.2°C, y = 2.98 

+ 0.33x. 

32 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
ACKNOWLEDGMENTS 

We thank Donald A. Reierson, Department of 

Entomology, University of California, Riverside, 

for his critical review and suggestions. This 

study was supported in part by a grant from U.S. 

Borax Research. 

REFERENCES 

Ebeling, Walter; Pence, Roy. 1957. Relation of 

particle size to the penetration of 

subterranean termites through barriers of 

sand or cinder. Journal of Economic 

Entomology 50: 690-692. 

Jones, Susan C.; Trosset, Michael W.; Nutting, 

William L. 1987. Biotic and abiotic 

influences on foraging of Heterotermes 

aureus (Snyder)(Isoptera: Rhinotermitidae). 

Environmental Entomology 16(3): 791-795. 

Pickens, A.L. 1934. The biology and economic 

significance of the western subterranean 

termite, Reticulitermes hesperus. In: 

Kofoid, Charles A., ed. Termites and 

termite control. Berkeley, Calif.: 

University of California Press; 157-183. 

Scott, Jeffrey G.; Matsumura, F. 1983. Evidence 

for two types of toxic action of 

pyrethroids on susceptible and DDTresistant German cockroaches. Pesticide 

Biochemistry and Physiology 19: 141-150. 

Smith, James L.; Rust, Michael K. Tunneling 

response and mortality of the western 

subterranean termite, Reticulitermes 

hesperus, (Isoptera: Rhinotermitidae) to 

soil treated with termiticides. Journal of 

Economic Entomology. [In press]. 

Su, Nan-Yao; Tamashiro, Minoru; Yates, Julian R.; 

Haverty, Michael I. 1982. Effect of 

behavior on the evaluation of insecticides 

for the prevention of or remedial control 

of the formosan subterranean termite. 

Journal of Economic Entomology 75: 188-193. 

Su, Nan-Yao; Tamashiro, Minoru; Yates, Julian R.; 

Haverty, Michael I. 1984. Foraging 

behavior of the Formosan subterranean 

termite (Isoptera: Rhinotermitidae). 

Environmental Entomology 13(6): 1466-1470. 

Tamashiro, Minoru; Su, Nan-Yao; Ebesu, R.H. 

1987. The Formosan subterranean termite in 

Hawaii: problems and control. In: 

Tamashiro, Minoru; Su, Nan-Yao, eds., 

Biology and control of the Formosan 

subterranean termite. Proceedings 67th 

Meet. Pacific Branch Entomol. Soc. Am. June 

25-27, 1985; Honolulu. Res. Ext. Ser. 083, 

Honolulu: Univ. Hawaii. 

Tukey, J.W. 1953. The problem of multiple 

comparisons. Princeton, N.J.: Princeton 

Univ. 

Williams, R. Michael C. 1977. The ecology and 

physiology of structural wood destroying 

Isoptera. Material and Organismen 12: 111-

140. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 33 
The Potential of Using Acoustical Emission to Detect Termites 

Within Wood1 

Vernard R. Lewis Richard L. Lemaster2 

Abstract: Acoustical emission (AE) equipment was 


used to detect drywood termites Incisitermes minor


in ponderosa pine Pinus ponderosa blocks under 


laboratory conditions. Using a 60 kHz transducer, 


AE levels were recorded for 0, 5, 10, 15, and 20 


termites per block. The association of AE and 


varying numbers of drywood termites best fit an 


exponential curve. These data suggest that the 


detection capabilities of AE increase with 


increasing numbers of termites. The implications 


of this finding to the potential use of AE in 


detecting termites under field conditions are 


discussed. 


In California, as many as 73 species of insects 


have been reported to cause damage to wooden 


structures (Ebeling 1975). Of these species, the 


subterranean termite Reticulitermes hesperus Banks 


and the drywood termite Incisitermes minor (Hagen) 


have had the greatest economic impact. Each year, 


more than 1.5 million inspection reports on 


termites and other wood-damaging pests are filed 


with the California Structural Pest Control Board 


(SPCB). Notices of Corrective Actions against 


these pests annually exceed 250,000, and the yearly 


costs of these inspections and control measures 


exceed $350 million (Brier and others 1988). 


In the past, control of termites within 


buildings relied heavily on the use of chlordane. 


However, because of problems involving 


environmental contamination and pesticide-related 


injuries, chlordane, along with many other 


pesticides, are no longer used or registered for 


control of wood-destroying insects. Since the 


discontinuance of the use of chlordane for 


subterranean termite control, recent reports reveal 


that termite control failures have increased as 


much as 30 percent (Katz 1989), and often result


in additional callback treatments. As the number


of callback treatments increases, there is concern 


that pesticide usage in urban areas, already more 


1

Presented at the Symposium on Current Research 


on Wood-Destroying Organisms and Future Prospects 


for Protecting Wood in Use, September 13, 1989, 


Bend, Oregon. 


2

Chancellor's Minority Postdoctoral Fellow, 


Department of Entomological Sciences, University of 


California, Berkeley, and Senior Research 


Specialist, Forest Products Laboratory, University 


of California, Berkeley. 


than 10 lb/acre, may also increase (National 


Academy of Sciences 1980). As a consequence, 


methods for reliable and accurate detection and 


control of termites are needed. 


Although new research shows promise for the 


development of nonchemical barriers, biological 


controls, attractants, and repellents for termites 


(Rust and others 1988), little has been done to 


improve inspections of structures. The use of 


electronic stethoscopes and dogs for detecting 


termites is gaining in popularity, though their 


utility has not yet been rigorously tested. On-


site visual inspection is still the dominant 


detection technique used by the industry. 


Unfortunately, visual inspection is highly 


subjective. Consequently, many of the 1,000 


complaints filed each year with the California SPCB 


result in litigation. 


Acoustic emission (AE) (the generation, 


transmission, and reception of energy in the form 


of vibrational waves in matter) (Kinsler and others 


1982) offers a potentially useful innovation for 


improving the detection of termites. The early 


applications of AE were for detecting defects and 


sounds emanating from metals (Dornfeld and 


Kannatey-Asibu 1980); however, new applications 


have been developed for machined wood (Lemaster and 


Dornfeld 1987), and sapwood trunk samples (Haack 


and others 1988). Although most AE studies are for 


stored grains and fruit-boring insects (Hansen and 


others 1988, Webb and others 1988), in Japan the 


Formosan subterranean termite (Coptotermes


formosanus Shiraki) has also been studied (Fujii 


and others 1990). 


Because of the economic losses caused by 


termites in California, and the need for improved 


detection of wood-destroying insects, we initiated 


a pilot study on the use of AE for detecting 


termites. The insect species studied was the 


drywood termite Incisitermes minor. This species 


was chosen because of its importance as a wood-


damaging pest and ease in laboratory rearing. 


METHODS 


A 6-mm diameter hole was drilled at the center 


of fifty ponderosa pine (Pinus ponderosa Dougl. ex 


Laws.) blocks (25 mm by 25 mm by 106 mm long). 


Each block was assigned to one of five groups of 10 


specimens each. The first group had 5 drywood 


termites inserted into each block. The number of 


drywood termites for the next three groups was 


increased by a multiple of 5, resulting in 10, 15, 


34 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
and 20 termites per block. The last group had no 


termites placed in the blocks, and served as the 


control. Each block was inspected using an 


acoustic emission amplifier (100 dB) and 60 kHz 


transducer. The emission signals emanating from 


each block for two 30-second periods were recorded 


at a threshold voltage of 1.1 volt and were input 


into a computer for analysis. 


RESULTS 


As the number of drywood termites increased 


within sample blocks, the AE that were produced 


increased exponentially (fig. 1). The amount of 


variance explained by this model was large (r2 = 


0.77). Multiple comparisons revealed significant 


differences among mean AE counts and drywood 


termite densities (table 1; F4,97 = 5.57, p < 


0.0005). Sample blocks with termites had AE 


counts three times greater than blocks with 5 


termites, six times greater than blocks with 10 


termites, three times greater than blocks with 15 


termites, and approximately thirty times greater 


than controls. Blocks with 5, 10, and 15 termites 


were not significantly different from controls. 


DISCUSSION 


The use of sound vibrations to detect termites 


in wood is not new. Thirty-five years ago, 


electronic stethoscopes were first proposed to 


detect termites (Pence and others 1954). This 


technology relied on the production of audible 


sound waves and the ability of the human ear to 


perceive them. The authors claimed that this 


device could detect the footfall sounds of a single 


termite. However, widespread adaptation of this 


new technology did not occur, possibly because (1) 


only a limited band of the total sound spectrum 


could be utilized (e.g., sound in the non-audible 


frequencies is also produced by termites), (2) 


large differences exist in hearing ability among 


individuals, and (3) false readings were produced 


due to excessive background noise levels. 


More recently, workers in Japan have used AE 


equipment to detect Formosan subterranean termites 


inside wood (Fujii and others 1990). They 


demonstrated that AE increased as the number of 


termites increased; however, the type of 


association (e.g., linear or nonlinear) was not 


mentioned. The results of our analysis reveal an 


exponential relationship between termite number and 


AE. This finding suggests (1) the sensitivity of 


AE equipment increases exponentially with increases 


in drywood termite number and (2) drywood termite 


behavioral interactions increase exponentially with 


increases in termite number. However, because 


closed wooden blocks were used to house termites, 


it was impossible to tell whether the AEs recorded 


were derived from feeding, head-banging, walking, 


or background noise level. Experiments currently 


under way at the University of California Forest 


Products Laboratory utilizing a video camera, 


recorder, AE sensor, and wooden blocks with 


plexiglass fronts will allow direct observation of 


Figure 1-- Nonlinear regression model for mean acoustic 

emission (AE) counts and number of drywood termites inside 

ponderosa pine blocks. Vertical bars represent ± SD. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 35 
Table 1--Mean acoustic emission (AE) counts for five 
 l
 densities of drywood termites inside ponderosa pine blocks.


—
 2


Density 


X AE counts (+SD)/30 sec


0 23.3 ( 7.5)a 


5 232.1 (163.9)a 


10 104.3 (128.3)a 


15 184.3 ( 92.6)a 


20 631.0 (405.6)b 


1

Each mean is based on AE recorded twice from each of 10 


pine blocks. 


2

Column means not followed by the same letter are 


significantly different (p < 0.05, Student-Keuls-Newman 


[SAS 19851 multiple range test). 


termite behavior during AE readings. These 


concurrent behavioral and acoustical observations 


will improve the correlation of AE events and 


related termite behaviors, as well as outline peak 


AE activity periods during the day. 


Additional areas of study are needed and 


include characterizing AE from different species of 


insects and wood and determining the number of 


sensors needed to inspect large pieces of wood. 


These later studies will better gauge AE as a 


diagnostic tool for detecting wood-damaging insect 


pests. This information is crucial for complying 


with the appropriate treatment recommendations 


mandated by the Structural Pest Control Board Act 


of California. 


ACKNOWLEDGMENT 


We thank Frank C. Beall and William A. Dost for 


technical assistance, Richard J. Brand for 


statistical advice, and F.L. Kala for reviewing the 


manuscript. This research was supported in part by 


the Forest Products Laboratory, University of 


California, Berkeley. 


REFERENCES 


Brier, A.N.; Dost, W.A.; Wilcox, W.W. 1988. 


Characteristics of decay and insect 


attack in California homes. California 


Agriculture 42(5): 21-22. 


Dornfeld, D.A.; Kannatey-Asibu, E. 1980. Acoustic 


emission during orthogonal metal cutting. 


International Journal of Mechanical Science 


22(5): 285-296. 


Ebeling, W. 1975. Urban entomology. Berkeley: 


University of California Division of 


Agricultural Sciences; 695 p. 


Fujii, Y.; Noguchi, M.; Imamura, Y.; Tokoro, M. 


1990. Using acoustic emission monitoring to 


detect termite activity in wood. Forest 


Products Journal 40(1): 34-36. 


Haack, R.A.; Blank, R.W.; Fink, F.T.; Mattson, W.J. 


1988. Ultrasonic acoustical emissions from 


sapwood of Eastern white pine, Northern red 


oak, red maple, and paper birch; implications 


for bark- and wood-feeding insects. The 


Florida Entomologist 71(4): 427-440. 


Hansen, J.D.; Webb, J.C.; Armstrong, J.W.; Brown, 


S.A. 1988. Acoustical detection of Oriental 


fruit fly (Diptera: Tephritidae) larvae in 


Papaya. Journal of Economic Entomology 81(3): 


963-965. 


Katz, H. 1989. What is the "Jugular Strategy." 


Pest Management 8(2): 14-15. 


Kinsler, L.E.; Frey, A.R.; Coppers, A.B.; Sanders, 


J.V. 1982. Fundamentals of acoustics, 3d ed. 


New York: John Wiley & Sons, Inc.; 480 p. 


Lemaster, R.L.; Dornfeld, D.A. 1987. Preliminary 


investigation of the feasibility of using 


acousto-ultrasonics to measure defects in 


lumber. Journal of Acoustic Emission 6(3): 157-


165. 


National Academy of Sciences. 1980. Urban pest 


management. Washington, D.C.: National Academy 


Press; 273 p. 


36 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Pence, R.J.; Magasin, S.J.; Nordberg, R.G. 1954. 
 SAS Institute. 1985. SAS/STAT guide for personal 


Detecting wood-boring insects. California 
 computers, Ver. 6 ed. Cary, North Carolina: SAS 


Agriculture 8(11): 5. 
 Institute, Inc.; 378 p. 


Rust, M.K.; Grace, J.K.; Wood, D.L.; Reierson, D.A. 
 Webb, J.C.; Litzkow, C.A.; Slaughter, D.C. 1988. 


1988. The search for new termite control 
 A computerized acoustical larval detection 


strategies. California Agriculture 42(5): 15-
 system. Applied Engineering in Agriculture 


18. 4(3): 268-274. 


USDA Forest Service Gen. Tech. Report PSW-128. 1991. 37 
Direct Colony Baiting of Termite Colonies: A Tool for 

Ecological Studies1 

Don McG. Ewart2 

Abstract: The benefits of direct colony 

baiting are described: bait substrates 

enclosed in polyvinyl chloride tubes are 

applied in direct contact with the 

galleries of the termite nest. Attention 

of researchers is drawn to the potential 

of this method for species other than the 

mound-building Coptotermes 1acteus. 

In the post-organochlorine era, 

knowledge of termite biology and 

behaviour is a precursor to effective 

control. This paper describes Australian 

experiences with termite baiting 

techniques and future directions for 

baiting research. 

EXPERIENCE WITH BAITING IN AUSTRALIA 

I first used baits to locate 

termites in 1979, after the method of La 

Fage and others (1973) as part of a study 

of the effects of removal of ground-wood 

by campers in Wyperfeld National Park in 

the desert of northwestern Victoria. By 

using rolls of toilet paper as baits and 

experimentally manipulating the wood 

supply it was possible to clearly show 

that fire-wood collection greatly 

diminished termite numbers (Ewart 1979). 

Baiting for termites in Australia 

has a long history, mostly the work of 

the CSIRO3 Division of Entomology in 

Canberra (Gay and others 1957). One 

enduring technique is the use of wood 

dowels to detect termites in trees 

1Presented at the Symposium on 

Current Research on Wood-Destroying 

Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 

1989, Bend, Oregon. 

2Lecturer, School of Early Childhood 

Studies, Institute of Education, The 

University of Melbourne, Priv. Bag 10, 

KEW VIC 3101, Australia 

3Commonwealth Scientific and 

Industrial Research Organisation 

(Greaves 1964). Dowel baits facilitate 

the detection of termites in living 

trees, without significant damage to the 

tree (Greaves and Florence 1966). The 

technique is simple: a hole is bored in 

the tree at about chest-height, and a 

snug-fitting dowel of a palatable 

eucalypt species is inserted to at least 

half the diameter. The dowel is likely 

to intercept termite galleries towards 

the center of the tree, where galleries 

are more abundant in the old heartwood. Within a few days, the dowel may be 

removed for inspection. The presence of 

termites may be determined by observing (i) fecal spotting on the bait, or (ii) 

cavities resulting from consumption of 

bait as food or excavation to re-open 

blocked galleries. If a suitable level 

of activity is detected, the dowel-hole 

may be treated with an insecticide, 

typically arsenic trioxide, although 

organochlorines and other termiticides 

have been used. The hole represents a 

potential entry point for other pests 

(Anon 1987), but this may be prevented by 

treatment with dieldrin (Greaves and 

Florence 1966). 

Along the Great Dividing Range of 

eastern Australia and extending to 

Tasmania grow the tallest flowering 

plants in the world. These are eucalypts 

of the subgenus Monocalyptus, fast 

growing fire-climax trees which typically 

grow in single-species stands. Their 

timber, though non-durable, is prized for 

indoor use and for paper pulp. In the 

early 1980's I began to examine termite 

attack on one of these species, 

Eucalyptus regnans Mueller, the Mountain 

Ash. 

In Victoria, vast even-aged forests 

of this species, which dated from a 

particularly bad cluster of wildfires in 

1939, were just then becoming of 

merchantable age. Early logging 

suggested that the trees contained a 

higher than expected rate of defect due 

to termites. Attacks on the heartwood of 

living trees were by Coptotermes species 

and a dampwood, Porotermes adamsoni 

(Froggatt). 

38 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Extraction of termites from mountain 

Ash is laborious and difficult and, 

unless you are prepared to sacrifice 

valuable sawlogs, involves coordination 

with commercial harvesting--following the 

fallers and collecting wherever possible. 

This is both extremely dangerous and 

unproductive. 

Given my earlier desert experiences, 

I preferred to have the termites come to 

me. I tried a range of baiting 

techniques with the aim of monitoring 

foraging activity: transects of rolls of 

toilet paper, buried wood blocks and 

dowel baits in standing trees. In 

Mountain Ash forests, it soon became 

clear that these termites do not normally 

forage near the surface of the ground, 

but are almost entirely restricted to the 

bole of the tree. My study was stalled 

for lack of access to the animals and was 

shortly thereafter dealt a death blow by 

wildfire. 

Wildfire did not necessarily affect 

the termites, but it drastically changed 

forest management and meant that the 

study sites would soon be clear-felled. It was at this rather low point that I 

first met Dr Jeffrey La Fage whilst he 

was visiting Dr John French. After some 

searching discussions and some 

particularly penetrating questions, I 

switched to baiting the termites where it 

was certain that they would be 

continually present--in their own mounds. 

MOUNDS OF COPTOTERMES LACTEUS 

Nests of Coptotermes lacteus 

(Froggatt) are typically formed in wood, 

usually within the center of a standing 

tree. The upper surfaces of the nest are 

always protected by a thick clay wall 

and, when the parent tree is lost, or the 

colony grows beyond the limits of the 

timber, an irregularly shaped mound is 

formed with the clay wall as the 

outermost surface (fig. 1). The outer 

wall is 20 to 60 cm thick and protects an 

extensive periecie. The spherical 

endoecie (or nursery) is situated at or 

below ground level. 

Direct baiting of mounds had been 

tried before without success; the 

experience then was that baits applied to 

the wall of the mound were soiled in 

place, but not attacked (Hunt and Snyder 

1931, Gay and others 1955). With 

corrugated cardboard in a short length of 

polyvinyl chloride (PVC) tubing, termites 

can be drawn from the periecie to bait 

units on the mound surface (French and 

Robinson 1985). 

Figure 1--Schematic cross-section of a 

mound of Coptotermes lacteus. 

This is not an entirely unnatural 

way of presenting food. Mounds initially 

form after tree-fall or premature 

cutting, and C. lacteus readily forage on 

branches or debris that either contact 

the exposed periecie or lie on the outer 

wall. Breaching of the wall or the 

accumulation of woody debris on the 

surface of the mound, or both, are not 

unusual circumstances. The PVC "fistula" 

bait units (French and Robinson 1985) 

merely standardize this food source. 

BAIT SUBSTRATES 

During trials to identify potential 

bait substrates, cork (bark of Quercus 

suber L.) was serendipitously discovered 

to be highly susceptible to attack 

(French and others 1986). Indigenous 

eucalypt timber and exotic softwood 

(Pinus radiata D. Don), although taken by 

termites in laboratory colonies (Gay and 

others 1955, Lenz and Barrett 1984), suffered only minor, erratic attack in 

the bait units, whereas with cork, a high 

proportion of baits were reliably 

attacked (fig. 2). 

BENEFITS OF DIRECT COLONY BAITING 

As a tool for the study of the 

ecology and biology of termites, direct 

baiting of termite colonies has many 

advantages over baits dispersed 

throughout their foraging territories. 

Response by the termites is obligatory-­ the bait substrate (or feeder strip) is 

applied in direct contact with freshly 

severed termite galleries. This security 

of response allows for the use of smaller 

sample sizes, with consequent economies 

of effort and expenditure. 

Variation in response to baits due to the 

(mostly seasonal) fluctuations in the 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 39 
effective size of foraging territories is 

minimized. Termites (C. lacteus at 

least) will forage close to the nest at 

times of climatic extremes. 

There can be absolute certainty as 

to which species and colony are 

responding to individual baits (and 

replicates). A major problem with area 

baitings that use rolls of toilet paper 

or graveyard stakes is that considerable 

uncertainties regularly arise as to the 

identity of species/colonies responsible 

for a fair proportion of the attack 

(Ewart 1979, Ferrar 1982, French and 

Robinson 1980, Usher 1975). 

With direct colony baiting, there is no 

need to employ large-footprint baits to 

attract termites (Akhtar and Jabeen 1981, 

French and Robinson 1980, Usher and Ocloo 

1974) or for baits large enough to 

sustain attack for the long exposures 

typically required to sustain significant 

attack (Howick and Creffield 1983). 

Baits may be small, and the tube to the 

periecie need only be of sufficient 

diameter to accommodate the expected 

number of foragers. Thus there are 

savings to be had from the use of smaller 

baits, and time savings as a turnover of 

baits from 7 to 28 days becomes 

effective. 

Wood blocks, stakes and rolls of 

toilet paper all suffer from the errors 

as they become cemented to the surface of 

the soil. Withdrawal of stakes often 

leaves many termites lost or crushed 

because of scraping, and inspection of 

toilet paper may cause the rolls to 

disintegrate, leaving many termites in 

Figure 2--Success rate of cork baits: 

Percentage of baits with termites 

present (n=80, 20 mounds, 4 baits per 

mound) at 18 consecutive monthly 

samples. 

40 

fractured galleries on the soil surface. 

By enclosing the bait in a close-fitting 

PVC tube, these errors are avoided. 

Inspection of the bait creates a 

clean break of galleries across a small 

surface area--and the tube may be 

replaced in exactly the same position, so 

that the integrity of the galleries is 

restored. Thus inspection of baits can 

occur with almost no disruption to the 

activity of the termites. Swapping of 

baits takes only a few seconds--one PVC 

tube is replaced by another containing a 

new bait block. Thus there is no need to 

wait for termites to discover the new 

block, as there has effectively been no 

interruption of exposure. This is a 

substantial improvement over the use of 

stakes, buried blocks, or rolls of toilet 

paper , because swapping of these baits 

causes significant damage to galleries 

and often requires the experimenter to 

re-excavate or level the surface. 

For all but a few species, when it 

is possible for the experimenter to 

directly observe foraging termites, it is 

likely that their normal behaviour has 

been disrupted by the conditions 

necessary for observation. The use of 

direct colony baiting and PVC fistulas 

enables instantaneous sampling of 

foraging groups. The bait unit can be 

removed and replaced before the termites 

have time to respond. Thus the termites 

collected by this system represent an 

instantaneous sample, delimited by an 

arbitrarily defined, but regularly 

replicable, break in the galleries at the 

end of the removable bait unit. The 

problems of galleries adhering to the 

bait are overcome by regulating these 

additions to a constant volume 

surrounding the bait block. The 

experimenter may transport the bait tube 

in a large vial, contents intact, for 

later dissection in the laboratory. 

OPPORTUNITIES FOR OTHER SPECIES. 

The system I have described is 

clearly well suited to sampling C. 

lacteus in mound populations, but just as 

it has its roots in the early toilet 

paper roll studies of the Sonoran Desert 

(La Fage and others 1973) and C. formosanus in Cypress stumps (La Fage and 

others 1973, 1975, 1976), and C. formosanus in Cypress stumps (La Fage and 

others 1983), it too can be modified for 

application to non-mound colonies. Treebased colonies are an obvious 

opportunity, as are some entirely 

subterranean species. The method is 

proven, the opportunities remain. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
REFERENCES 

Akhtar, Muhammad S.; Jabeen, Mussarat. 

1981. Influence of specimen size on 

the amount of wood consumed by 

termites. Pakistan Journal of 

Zoology 13(1&2): 79-84. 

Anon. 1987. Wood sampling checks 

quality. Between the leaves. 

Queensland Department of Forestry, 

May 1987. 

Ewart, Don McG. 1979. An investigation 

of the ecology of subterranean 

termites which utilize woody litter 

at Wyperfeld National park. Honours 

Thesis, Department of Zoology, La 

Trobe University, Australia. 

Ferrar, Paul 1982. Termites of a South 

African savanna. III. Comparative 

attack on toilet roll baits in 

subhabitats. Oecologia 52: 139-146. 

French, John R.J.; Robinson, Peter, J. 

1980. Field baiting of some 

Australian subterranean termites. 

Zeitschrift für Angewandte 

Entomologie 90: 444-449. 

French, John, R.J.; Robinson, Peter, J. 

1985. A technique used on mounds of 

Coptotermes lacteus to screen 

potential bait substrates. Journal 

of the Australian Entomological 

Society 24: 111-112. 

French, John, R.J.; Robinson, Peter, J.; 

Ewart, Donald M. 1986. Mound 

colonies of Coptotermes lacteus 

(Isoptera) eat cork in preference to 

sound wood. Sociobiology 11(3): 303-

309. 

Gay, Francis J.; Greaves, Tom; Holdaway, 

F.G.; Wetherley, A.H. 1957. The 

development and use of field testing 

techniques with termites in 

Australia. Commonwealth Scientific 

and Industrial Research 

Organisation, Melbourne, Australia. 

Bulletin no. 208. 

Gay, Francis J.; Holdaway, F.G.; 

Wetherley, A.H. 1955. Standard 

laboratory colonies of termites for 

evaluating the resistance of timber, 

timber preservatives and other 

materials to termite attack. 

Commonwealth Scientific and 

Industrial Research Organization, 

Melbourne, Australia. Bulletin no. 

277. 

Greaves, Tom 1964. Temperature studies 

on termite colonies in living trees. 

Australian Journal of Zoology 12: 

250-262. 

Greaves, Tom; Florence, R.G. 1966. 

Incidence of termites in Blackbutt 

regrowth. Australian Forestry 30: 

153-161. 

Haverty, Michael I.; La Fage, Jeffrey P.; 

Nutting, William L. 1974. Seasonal 

activity and environmental control 

of foraging of the subterranean 

termite, Heterotermes aureus 

(Snyder), in a desert grassland. 

Life Sciences 15(6): 1091-1101. 

Haverty, Michael I.; Nutting, William L.; 

La Fage, Jeffrey, P. 1975. Density 

of colonies and spatial distribution 

of foraging territories of the 

desert subterranean termite, 

Heterotermes aureus (Snyder). 

Environmental Entomology 4(1): 105-

109. 

Haverty, Michael I.; Nutting, William L.; 

La Fage, Jeffrey P. 1976. A 

comparison of two techniques for 

determining abundance of 

subterranean termites in an Arizona 

desert grassland. Insectes Sociaux 

23(2): 175-178. 

Howick, C. Doug; Creffield, Jim W. 1983. 

A rapid field bioassay technique 

with subterranean termites. 

International Research Group on Wood 

Preservation, Doc. No. IRG/WP/1188, 

IRG Secretariat, Stockholm. 

Hunt, G.M.; Snyder, T.E. 1931. An 

international termite exposure test. 

Proceedings of the American Wood 

Preservation Association 1931: 

279-286. 

La Fage, Jeffrey P.; Haverty, Michael I.; 

Nutting, William L. 1976. 

Environmental factors correlated 

with foraging behaviour of a desert 

subterranean termite, Gnathamitermes 

perplexus (Banks) (Isoptera: 

Termitidae). Sociobiology 

2:155-169. 

La Fage, Jeffrey P.; Nutting, William L.; 

Haverty, Michael I. 1973. Desert 

subterranean termites. A method for 

studying foraging behaviour. 

Environmental Entomology 2: 954-956. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 41 
La Fage, Jeffrey P.; Su, Nan-Yao; Jones, 

M.J.; Esenther, G.R. 1983. A rapid 

method for collecting large numbers 

of subterranean termites from wood. 

Sociobiology 7(3): 305-309. 

Lenz, Michael; Barrett, Robert A. 1984. 

Implications for comparability of 

laboratory experiments revealed in 

studies on vigour in Coptotermes 

lacteus (Froggatt) and Nasutitermes 

exitiosus (Hill) (Isoptera: 

Rhinotermitidae and Termitidae). 

Bulletin of Entomological Research 

74: 477-485. 

Usher, M.B. 1975. Studies on a 

wood-feeding termite community in 

Ghana, West Africa. Biotropica 

7(4): 217-233. 

Usher, M.B.; Ocloo, J.K. 1974. An 

investigation of stake size and 

shape in ‘graveyard’ field tests for 

termite resistance. Journal of the 

Institute of Wood Science 9: 32-36. 

42 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Behavioral Ecology of Subterranean Termites and Implications 

for Control1 

J. Kenneth Grace2 

Abstract: Subterranean termites are important structural pests 

in much of North America, and worldwide. Recent studies of 

eastern subterranean termite (Reticulitermes flavipes [Kollar]) 

colonies in Ontario, Canada, indicate that these colonies 

contain greater foraging populations and forage over larger 

territories than was previously thought to be the case. These 

results are consistent with those obtained elsewhere with 

Coptotermes formosanus Shiraki and Heterotermes aureus 

(Snyder). Implications for the development of baiting 

techniques for termite control are discussed, and several 

laboratory investigations of potential bait toxicants and 

insecticidal dusts are reviewed. Behavioral chemicals are also 

potentially useful in termite control, and bioassays with tree 

extractives indicate that semiochemicals affecting termite 

orientation offer an explanation for the observed pattern of R. 

flavipes infestation in street trees in Toronto. 

The eastern subterranean termite (Reticulitermes flavipes 

[Kollar]) (Isoptera: Rhinotermitidae) has a broad distribution 

in North America, extending from the southeastern United 

States to the Great Lakes (Weesner 1970). At the northern 

edge of this distribution, R. flavipes was first reported at Point 

Pelee, Ontario, in 1929, and was apparently introduced to 

Toronto in infested materials brought by ship from the United 

States about 1935 (Kirby 1965; Urquhart 1953). To date, 

infestations have been reported from thirty municipalities in 

southern Ontario, with Kincardine (44°11'N, 81°38'W) 

representing the northernmost site of established R. flavipes 

infestations. Outside of buildings, flights of R. flavipes alates 

are rare in Ontario, and the disjunct distribution of termites in 

the province results from movement of infested wood (firewood 

or used lumber). In 1987, a Reticulitermes infestation of several 

years standing was also discovered in a block of homes in 

Winnipeg, Manitoba, indicating the potential for further 

northern distribution of this genus. 

1

Presented at the Symposium on Current Research on 

Wood-Destroying Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 1989, Bend, Oregon. 

2

Adjunct Professor, Faculty of Forestry, University of 

Toronto, Toronto, Ontario, Canada. 

3

Currently: Assistant Professor, Department of Entomology, 

University of Hawaii at Manoa, Honolulu, Hawaii. 

TERMITE TERRITORIES AND BAITING STRATEGIES 

Grace and others (1989) recently evaluated the size of R. 

flavipes foraging territories and populations at two sites in 

metropolitan Toronto. These mark-release-recapture studies 

employed the dye Sudan (Fat) Red 7B (Grace and Abdallay 

1989) with methodology similar to that of Su and Scheffrahn 

(1988) with Coptotermes formosanus Shiraki and Jones (1987) 

with Heterotermes aureus (Snyder). As was the case with these 

latter two species, eastern subterranean termite colonies were 

found to cover larger areas and contain greater foraging 

populations than previously suspected. At one site, the 

foraging population was estimated at 3.2 million termites, 

moving over a territory of 1,091 m2

 (Grace and others 1989). 

Continuing studies at these two field sites and at other 

locations in Ontario have confirmed the general applicability of 

these results (Grace 1990a). Additional dyes (Grace and 

Abdallay 1990a) would be useful in improving the precision of 

population estimates. 

It is interesting to note that the mark-release-recapture 

studies with R. flavipes were conducted around buildings 

chemically treated for subterranean termite control, emphasizing 

that the "chemical barrier" around treated structures has little 

effect on termite populations outside that narrow band of 

pesticide-treated soil. As is mentioned elsewhere in these 

proceedings, the use of toxic baits appears to be the most 

reasonable method of attacking these populations. In regions 

where subterranean termites are ubiquitous, such baits would 

likely be employed to extend the protected area outward from 

the structures at risk. Baits would have to remain in place 

following the death of colonies in the baited zone to intercept 

foragers entering the area from expanding colonies in adjacent 

areas, as well as foragers from any new alate-founded colonies. 

However, in northern regions with a disjunct pattern of 

Reticulitermes infestation and limited occurrence of alate flights, 

it should be possible to eradicate isolated infestations, with a 

low probability of re-introduction. Active foraging by colony 

groups over large areas implies that bait placement is perhaps 

less critical than would be the case with localized foraging 

parties, and that a few baits could affect a large termite 

population impinging upon multiple buildings. 

Toxicants intended for use in baits should be nonrepellent 

and slow-acting (Su and others 1987). Certain borate 

compounds (Grace 1990b) fit these criteria, although rather 

high dietary concentrations are required to kill termites. An 

alternative, although more labor intensive, approach may be to 

apply borate (or other insecticidal) dusts in a toxic variation of 

mark-release-recapture methodology. Grace and Abdallay 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 43 
(1990b) demonstrated in laboratory assays that coating 5-10 

percent of the individuals in groups of 20-40 R. flavipes workers 

with boric acid or barium metaborate dusts resulted in 28-100 

percent mortality within 16 days. Subterranean termite foragers 

collected in traps such as those described by Grace (1989) and 

Su and Scheffrahn (1986) could be coated with such toxic dusts 

and released back into the traps to poison other colony 

members through mutual grooming behaviors. Collections from 

multiple traps at each site and multiple capture and release 

cycles could be employed to treat a sufficiently large proportion 

of the population to kill the entire colony. 

An alternative to the use of chemical insecticides in termite 

baiting systems is the use of microbial biological control agents, 

such as nematodes or fungi. In Ontario, and other areas of 

subterranean termite introductions, surveys of the mycoflora 

associated with termites may reveal potential pathogens. Zoberi 

and Grace (1990a) isolated 40 fungal species from R flavipes 

and associated materials. Several of these fungi have been 

previously reported to be facultative insect pathogens, and a 

number (e.g., Arthrobothrys oligospora Fresenius, 

Cunninghamella echinulata Thaxter, and Rhizopus stolonifer 

Ehrenb. ex Fr.) appear to be detrimental to termite survival in 

preliminary bioassays. The well-known pathogenic fungus 

Beauveria bassiana [Balsamo] Vuillemin was also recently 

isolated from R. flavipes workers infesting a street tree in 

Toronto (Zoberi and Grace 1990b). 

Although attractant or arrestant semiochemicals would be 

useful in masking otherwise repellent bait toxicants, the high 

level of foraging activity of R. flavipes at field sites in Ontario 

indicates that neither decayed wood nor attractant chemicals are 

necessary prerequisites to implementation of baiting techniques, 

so long as the feeding substrate or bait toxicant within the 

collection unit is not repellent. Use of a collection trap is 

certainly more labor intensive than placement of the toxicantimpregnated decayed-wood blocks originally used to control 

termites in this manner (Ostaff and Gray 1975). However, it 

also offers more control possibilities (such as incorporating 

dusts) and a means of quantifying the decline in the termite 

population by post-treatment monitoring and mark-releaserecapture methods. Post-treatment bait units, supplemented by 

wooden stakes, could remain in place both to confirm the 

efficacy of the control method and as an aid in subsequent 

inspections of the property for new termite infestations. 

SEMIOCHEMICALS IN ORIENTATION AND FEEDING 

Eastern subterranean termite responses to behavioral 

chemicals (semiochemicals) may help to explain observed 

patterns of termite foraging, and may also be useful adjuncts to 

baiting systems. Low concentrations of the microbicide 

TCMTB, for example, are repellent to R. flavipes, and might 

protect wood from termite attack more effectively than toxic 

but nonrepellent preservatives (Grace 1988). Attractants and 

arrestant semiochemicals, on the other hand, might be used to 

enhance feeding on baits and to direct foragers towards baits or 

toxicant-treated soil. Reticulitermes workers are able to orient 

to chemical gradients, both on two-dimensional trails (Grace 

and others 1988) and diffused through the soil (Clement and 

others 1988). 

In Toronto and other northern locales, R. flavipes infests 

living trees as well as cellulosic debris and wood in service. 

Shelter tubes are constructed in bark fissures upward from the 

base of the tree stem, and termites are active between the 

inner and outer bark. Although feeding is limited to dead 

portions of the tree, such as the heartwood and fungus-decayed 

limbs, some scarring of the bark and sapwood surfaces is also 

apparent. 

In 1980, an inspection of 17,800 street and park trees in 

metropolitan Toronto revealed termite shelter tubing on 4 

percent of those trees (Cooper and Grace 1987). Subsequently, 

two tree species commonly occurring in Toronto were selected 

to determine whether chemical factors were involved in the 

pattern of differential infestation of street trees observed in the 

1980 survey. Subterranean termite tubing was found on 19.3 

percent of the horsechestnuts (Aesculus hippocastanum L.) 

(Hippocastanaceae) inspected, ranking it as a frequently 

infested tree species. On tree of heaven (Ailanthus altissima 

[Mill.] Swingle) (Simaroubaceae), however, shelter tubing was 

noted on only 0.7 percent of the trees inspected, suggesting 

that it is rarely infested (Cooper 1981). 

The bark, sapwood, and heartwood of these two tree 

species were each extracted in a series of solvents 

(chloroform:acetone, methanol, acetone, hexane), and the 

resulting extracts applied to filter paper and exposed to R. 

flavipes workers in no-choice laboratory assays (Grace, in 

preparation).4 All extracts were assayed at 4 percent 

(weight/weight) concentrations, although the yields from 

extraction ranged from 0.3-10.2 percent (wt./wt.). Only the 

hexane extract of A. altissima heartwood caused significant 

termite mortality within 15 days. However, the yield of hexane 

extractives from A. altissima heartwood was only 0.3 percent 

(wt./wt.). Since it was assayed at a 4 percent concentration, this 

suggests that less mortality might be expected from termite 

feeding on the natural substrate. 

The orientation responses of individual R. flavipes workers 

to these extracts were evaluated in behavioral assays (Grace, in 

preparation).4 In these assays, a single worker was placed 

between a 23 mm diameter paper disk treated with 4 percent 

(wt./wt) extractives and a second solvent-treated control disk in 

a small glass petri dish. The position of the worker (in contact 

with either or neither paper disk) was recorded every 30 

seconds over a 20-minute interval. This assay was repeated 

with 50 workers exposed to each of the 12 extracts from the 

two tree species, and the proportions in contact with the 

extract-treated and the control disks compared (pairedcomparisons t test). Seven of the 12 horsechestnut extracts 

elicited significant (p ≤ 0.05) positive orientation responses, and 

3 elicited significant negative responses. The opposite trend 

4

Data on file, Department of Entomology, University of 

Hawaii, Honolulu, Hawaii. 

44 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
was observed with tree of heaven, for which 7 of the solvent 

extracts elicited negative responses, and only two elicited 

positive responses. In addition, the A. hippocastanum 

extractives eliciting the strongest positive orientation responses 

and the A. altissima extractives eliciting the strongest negative 

responses were present in high concentration in their respective 

wood matrices. Thus, semiochemical-mediated orientation 

behavior and initiation of feeding on a particular tree species 

may explain differential infestation of otherwise equally suitable 

substrates. 

ACKNOWLEDGMENTS 

These studies were supported by grants from the Ontario 

Ministry of the Environment, Ontario Ministry of Housing, 

Canada Mortgage and Housing Corporation, Ontario Real 

Estate Association Foundation, Toronto Real Estate Board, US 

Borax Corporation, and the municipalities of East York, 

Etobicoke, Guelph, Hamilton, Kincardine, Leamington, North 

York, Oakville, Scarborough, and Toronto. 

REFERENCES 

Clement, J.L.; Lemaire, M.; Nagnan, P.; Escoubas, P.; Bagneres, 

A.G.; Joulie, C. 1988. Chemical ecology of European 

termites of the genus Reticulitermes. Allomones, 

pheromones and kairomones. Sociobiology 14: 165-174. 

Cooper, P.A. 1981. The subterranean termite (Reticulitermes 

flavipes) - its activity and control in shade trees. Toronto: 

Faculty of Forestry, Univ. of Toronto. 25 p. Final Report 

to the Ontario Shade Tree Council. 

Cooper, P.A.; Grace, J.K. 1987. Association of the eastern 

subterranean termite, Reticulitermes flavipes (Kollar), with 

living trees in Canada. Journal of Entomological Science 

22: 353-354. 

Grace, J.K 1988. Toxicity and repellency of the fungicide 

TCMTB to the eastern subterranean termite (Isoptera: 

Rhinotermitidae). Proceedings of the Entomological Society 

of Ontario 119: 83-85. 

Grace, J.K. 1989. A modified trap technique for monitoring 

Reticulitermes subterranean termite populations (Isoptera: 

Rhinotermitidae). Pan-Pacific Entomologist 65: 381-384. 

Grace, J.K. 1990a. Mark-recapture studies with Reticulitermes 

flavipes (Isoptera: Rhinotermitidae). Sociobiology. [In 

press]. 

Grace, J.K 1990b. Oral toxicity of barium metaborate to the 

eastern subterranean termite (Isoptera: Rhinotermitidae). 

Journal of Entomological Science. [In press]. 

Grace, J.K.; Abdallay, A. 1989. Evaluation of the dye marker 

Sudan Red 7B with Reticulitermes flavipes (Isoptera: 

Rhinotermitidae). Sociobiology 15: 71-77. 

Grace, J.K.; Abdallay, A. 1990a. A short-term dye for marking 

eastern subterranean termites (Reticulitermes flavipes Koll., 

Isoptera, Rhinotermitidae). Journal of Applied Entomology. 

[In press]. 

Grace, J.K.; Abdallay, A. 1990b. Termiticidal activity of boron 

dusts (Isoptera, Rhinotermitidae). Journal of Applied 

Entomology. [In press]. 

Grace, J.K; Abdallay, A.; Farr, KR. 1989. Eastern subterranean 

termite (Isoptera: Rhinotermitidae) foraging territories and 

populations in Toronto. Canadian Entomologist 121: 551-

556. 

Grace, J.K.; Wood, D.L.; Frankie, G.W. 1988. Trail-following 

behavior of Reticulitermes hesperus Banks (Isoptera: 

Rhinotermitidae). Journal of Chemical Ecology 14: 653-

667. 

Jones, S.C. 1987. Foraging Party and Territory Size of the 

Desert Subterranean Termite Heterotermes aureus (Snyder) 

in a Sonoran Desert Grassland. Tucson: Univ. of Arizona; 

Ph.D. Dissertation. 

Kirby, C.S. 1965. The distribution of termites in Ontario after 

25 years. Canadian Entomologist 97: 310-314. 

Ostaff, D.; Gray, D.E. 1975. Termite (Isoptera) suppression 

with toxic baits. Canadian Entomologist 107: 1321-1325. 

Su, N.-Y.; Scheffrahn, R.H. 1986. A method to access, trap, 

and monitor field populations of the Formosan 

subterranean termite (Isoptera: Rhinotermitidae) in the 

urban environment. Sociobiology 12: 299-304. 

Su, N.-Y.; Scheffrahn, R.H. 1988. Foraging population and 

territory of the Formosan subterranean termite (Isoptera: 

Rhinotermitidae) in an urban environment. Sociobiology 14: 

353-359. 

Su, N.-Y.; Tamashiro, M.; Haverty, M.I. 1987. Characterization 

of slow-acting insecticides for the remedial control of the 

formosan subterranean termite (Isoptera: Rhinotermitidae). 

Journal of Economic Entomology 80: 1-4. 

Urquhart, F.A. 1953. The introduction of the termite into 

Ontario. Canadian Entomologist 85: 292-293. 

Weesner, F.M. 1970. Termites of the nearctic region. In: 

Krishna, K; Weesner, F.M., eds. Biology of termites, 

volume II. New York: Academic Press; 477-525. 

Zoberi, M.H.; Grace, J.K. 1990a. Fungi associated with the 

subterranean termite Reticulitermes flavipes (Kollar) in 

Ontario. Mycologia [In press]. 

Zoberi, M.H.; Grace, J.K. 1990b. Isolation of the pathogen 

Beauveria bassiana from Reticulitermes flavipes (Isoptera: 

Rhinotermitidae). Sociobiology. [In press]. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 45 
--------------------------------------- 

Baiting Techniques for Control of Coptotermes Species Within

Existing Buildings in Australia1 

J.R.J. French2 

Abstract: Baiting techniques have been developed over the 

years to control Coptotermes species, the most economically 

important termite species in Australia. Given the 

restrictions on organochlorines as termiticides in North 

America, this paper highlights research that has focussed 

on baiting programs against Coptotermes as alternatives to 

current control measures: drenching soil with pesticides or 

fumigation of entire structures. Details of the baiting 

procedures, toxins used, and their suitability for use in 

eradicating Coptotermes infestations in existing buildings 

are described. Suggestions are offered for the direction in 

which future baiting techniques may prove productive. 

---------------------------------------------------------------------------

In Australia subterranean termites cause most of the 

termite damage to timber in service (French 1986). Of 

these termites, the most economically important are the 

Coptotermes species. Inarguably, protection from 

subterranean termites has come to depend almost entirely 

on soil barriers (Lenz and others 1988), with the use of 

toxic, persistent chemicals such as organochlorines and the 

organophosphate chlorpyrifos. Dusting termites in galleries 

and sheltertubes with arsenic trioxide is still permitted and 

is normally the first step in eradicating subterranean 

termites from existing buildings, followed by a soil 

treatment. 

The risk to the public of these chemicals is underrated, 

and partially unknown. Yet for the last 20 years these 

treatments have been standardized and recommended for 

use by local governments and the pest control industry (see 

Australian Standard (AS) 2057-1986; AS-2178-1986). The 

application of these persistent organochlorines as chemical 

soil barriers has ecological and practical limitations, as was 

pointed out by Beard (1974). There are many situations 

within existing buildings that render their use and 

application impracticable. For instance, termites infesting 

timber in apartments above the ground floor level are 

difficult, if not impossible, to control with the 

conventional chemical barrier treatments. 

1 Presented at the Symposium on Current Research on 

Wood-Destroying Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 1989, Bend, 

Oregon. 

2 Principal Research Scientist, CSIRO, Division of Forestry 

and Forest Products, Graham Rd, Highett, Vic. 3190. 

Australia. 

Many dusting treatments using arsenic trioxide fail to 

destroy the whole termite colony, because too few termites 

are "dusted," and these do not return to the nest. Thus, the 

damage continues. Furthermore, there is a lack of scientific 

data to indicate precisely how effective all these chemical 

treatments are in controlling subterranean termites in both 

the urban and rural environments. Alternative treatments 

are virtually unknown. The outcome is that the pest control 

industry in Australia (and the United States) has fewer and 

fewer options. 

Apart from the physical nature of organochlorines, 

misuse of persistent termiticides by the pest control 

industry and increased public awareness of persistent home 

contamination and human exposure to organochlorine 

termiticides have contributed to these chemicals being 

severely restricted or banned in some countries around the 

world. In North America, the main manufacturers have 

voluntarily ceased production of organochlorines, whereas 

in Japan, organochlorines are banned, and only the 

organophosphate, chlorpyrifos (=Dursban), and several 

synthetic pyrethroids are registered for termite control. 

French and La Fage (1989) outlined the various treatments 

used around the world against the most economically 

important subterranean termite species. 

Although I am aware of the need to refine effective 

and environmentally safer substitutes for organochlorines 

and arsenicals in termite control, this paper presents the 

results of some experiments carried out in southeastern 

Australia over the past decade, and offers some practical 

refinements regarding arsenic trioxide treatments, and 

alternatives (such as bait systems) to the pest control 

industry. I hope that some of these techniques may be 

adapted for North American conditions. In Australia, I 

have concentrated on the use of baits to aggregate termites 

(in this paper, the term 'termites' refers to subterranean 

termites' unless otherwise mentioned) in mounds and those 

that are infesting buildings, and the judicious use of small 

amounts of toxins to kill these colonies. The toxins referred 

to in this paper are arsenic trioxide and mirex. 

The efficacy of mirex against termites in North 

America was demonstrated by Esenther and Gray (1968), 

Beard (1974), Esenther and Beat (1974, 1978, 1979) and 

Esenther (1979). In Australia, Paton and Miller (1980) 

found that less than 1 g of mirex was required to kill a 

colony of the Giant Northern termite (Mastotermes 

darwiniensis Froggatt), whereas French (unpubl. data) 

found that less than 0.25 g mirex was effective against a 

colony of Coptotermes lacteus (Froggatt). By way of 

contrast, an average 15 square building (1 square = 10 ft2) 

necessitates about 3 kg of active ingredient (i.e., 

organochlorine or organophosphate), using the Australian 

46 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Standard, whereas less than 1 g of mirex in wood-decay 

bait-blocks can suppress an active Coptotermes 

acinaciformis (Froggatt) colony in a building. Although 

mirex is considered a carcinogen by some and has been 

banned in North America, there has been no report of 

injury to a person by mirex, and the chemical has not been 

measured in persons with occupational exposure to the 

compound. 

Mirex is currently registered under special permit to 

licenced pest control operators (PCOs) for controlling M. 

darwiniensis in north Queensland, the Northern Territory 

and northwest Western Australia. I am currently negotiating 

with the Victorian and New South Wales State 

Governments to allow the use of mirex under a special 

permit by licenced PCOs. 

There are two main areas to apply baits against termites: 

(a) within and under buildings, and (b) around buildings, 

in termite mounds and in termite-infested trees. 

Prefabrication of the bait-containers is similar for both 

situations. However, whether inside or outside the building, 

location of active termites is the single most important 

factor. There is no substitute for a thorough and careful 

search in and around a building to locate active termite 

sheltertubes or galleries. Sometimes the termite nest may be 

located either in an above-ground mound or in a standing 

tree or stump. 

Regardless of the location, the following procedures for 

aggregating Coptotermes species in bait-containers have 

been used. Although the application of the toxin may vary, 

the aim of this control technique is to destroy an active 

termite colony with a slow-acting stomach poison that will 

be distributed throughout the colony by foraging termites. 

ARSENIC TRIOXIDE BAIT CONTAINERS 

Box-Bait Container 

Box-bait containers for use under a suspended floor 

may be made from 3-ply veneer, and measure 600 x 300 x 

200 mm, with four slits (3 mm wide, 460 mm long) cut 

into the bottom board. The box is filled with layers of 

corrugated cardboard wetted with water, and the box 

sealed with a lid. The box is buried to half its depth into 

the soil alongside or near active termite sheltertubes on 

walls or stumps. Water is applied to the soil around the 

box. After seven days the box container should be 

inspected for termites. The cardboard should be doused 

again if no termites present after this period. 

Pipe-Bait Container 

The pipe-bait container consists of a plastic pipe (90 

mm diameter, 300 mm long), into which two corrugated 

cardboard inserts (with corrugations inwards and measuring 

60 and 240 mm wide respectively) are placed. A petri dish 

lid seals the end with the longest cardboard insert. The 

whole arrangement is buried upright into the soil alongside 

or near active termite sheltertubes on walls or stumps, to a 

depth of about 50 mm. The inserts and the ground around 

the pipe are soaked with water. Inspections for termite 

activity are made every week, and the system is rewatered 

if necessary. 

Conduit-Box Bait Containers in Ground 

Plastic conduit (25 mm diameter), with small holes (4 

mm diameter) drilled every 100 mm, with a wetted 

corrugated cardboard insert is buried (ca. 100-150 mm 

depth) alongside or near sheltertubes, diagonally across the 

underhouse area, or around the outside of the building. 

Plastic tee-pieces are inserted about every meter with an 

upright piece of tubing (200 mm long) onto which is 

attached a small plastic box (200 x 130 x 100 mm) filled 

with layers of wetted corrugated cardboard. Before 

backfilling the conduit-box arrangement into the trench, 

water is poured the length of the trench. Inspections for 

termite activity in the plastic boxes may be made every 

week, and re-watered if necessary. 

Conduit-Box Bait Container in Tree 

In southeastern Australia, old, damaged eucalypt trees 

are a favored site for Coptotermes colonies. However, it is 

rarely possible to visually detect an active termite nest 

within a tree. So, a hole is drilled (ca. 18 mm diameter) 

into the base of the tree. If the tree is hollow at the center, 

indicating a possible nest, this is detected when drilling. On 

withdrawing the drill, wet mud and maybe parts of 

termites may be seen, indicating an active nest. Often, 

termite bodies are not found, and this necessitates placing a 

wood dowel into the drilled hole. Allow about 100 mm to 

extend beyond the tree trunk so that it may be withdrawn 

easily. Leave the dowel in position for 2 to 10 h, then 

remove the dowel. If the dowel cannot be withdrawn 

easily, and requires a sharp tug, this indicates an active 

nest. The termites will have "sealed in" the dowel. After the 

dowel is removed termites are usually found on its surface. 

At this point, a conduit-box bait-container may be inserted. 

The conduit-box bait-container is designed as follows. 

A plastic conduit (400 mm long, 16 mm diameter) is glued 

into a plastic rectangular container (300 x 200 x 95 mm) so 

that it protrudes (200 mm) from one of the longest sides. 

Small holes (8 mm diameter) are drilled in the conduit 

within the container, giving termites passing into the 

conduit access to the interior of the container. A 

corrugated cardboard insert is arranged within the length 

of the conduit. Layers of corrugated cardboard completely 

occupy the interior of the container, and these are slightly 

wetted with water. A lid is then secured in position. 

Termites enter the box-container via the conduit, and 

can be removed, treated outside the container with arsenic 

dust (see below for treatment details), and returned to the 

container. The lid is not replaced; this causes a mass exodus 

back into the tree. Usually, if a sufficient number of 

termites are treated, the colony will collapse within 6 to 10 

days. Termite activity may be gauged by withdrawing the 

box-container, and inserting a wood dowel. If after 1 to 2 

days the dowel has not been "mudded in," the nest can be 

considered to have been destroyed. Rarely is it necessary to 

use more than 3-5 g of arsenic trioxide to eradicate an 

entire colony. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 47 
Applying Arsenic Trioxide to Termites in Baits 

Irrespective of the design of the bait-container, the 

general principle in applying arsenic trioxide onto the 

termites aggregated in the baits is similar. If, on inspecting 

inside the bait-container, you see several hundred termites 

walking on the corrugated paper, remove the paper, hold 

it vertically over a large tray (e.g., a film developing tray is 

ideal), then give the back of your hand holding the paper a 

sharp smack. The termites will drop off the paper into the 

tray. Transfer about 80 percent of the termites from the 

bait-container, using the papering method, and put them 

into a container with a tight-fitting lid. Dust them with 

arsenic trioxide. Take adequate safety precautions by 

wearing goggles, respirator, and gloves. Rotate the closed 

container, and ensure that the termites are well covered 

with arsenic trioxide. The dusted termites are deposited 

back into the bait-container and onto the untreated 20 

percent that are rapidly moving back into the gallery 

systems. Given that several hundred termites can be dusted 

in this manner, I would expect a complete collapse of the 

colony within 6 to 10 days. 

After about two weeks, inspect the building for signs of 

active termites. If none are seen, one can assume the 

destruction of the colony was successful, and the baitcontainers may be withdrawn from the area. 

"Trojan Termite" Technique 

The "trojan termite" technique (coined by the author) 

refers to the technique of "dusting" several hundred 

Coptotermes individuals from one colony source with 

arsenic trioxide and placing them immediately into the 

gallery systems of Coptotermes termites infesting timbers in 

a building. The "trojan termites" do not have to be of the 

same species, but basically should be the same size. After 

the dusted termites are inserted into the galleries of the 

"host" colony, the sections that have been opened to allow 

their placement are left open, to speed up the dispersal of 

the dusted termites into the gallery systems. Efficacy of 

this technique ought to be equivalent to bait-container 

techniques. 

MIREX-TREATED BAIT-BLOCKS 

In the laboratory radiata pine (Pinus radiata D. Don) 

sapwood stakes (500 x 58 x 18 mm, with the grain running 

lengthwise) are buried to a depth of 450 mm in moist 

forest or woodland soil within large containers in the 

Artificial Fungal Simulator (AFS). Stakes are removed after 

12-15 weeks when there is about 15-20 percent mass loss 

per stake due to wood-decay fungi activity. Adhering soil 

is removed, and the stakes are sterilized in an autoclave at 

120°C for 1 h. After autoclaving, blocks measuring about 

58 x 58 x 18 mm are cut from the sterilized stakes. They 

are impregnated by dip diffusion in a 0.4 percent solution 

of mirex in acetone for 30 seconds, and the solvent allowed 

to evaporate. The decayed-wood mirex-treated blocks are 

then ready for use, and should be kept in plastic bags until 

required. 

Placement of Mirex-Treated Bait-Blocks 

Mirex-treated wood-blocks are placed either in 

buildings, outside buildings, or in both locations. 

In Buildings 

Place in Active Galleries--When termites are detected 

infesting architraves, window frames, mouldings, skirting 

boards, in flooring, in structural timbers behind panelling, 

and other timber constructions, the mirex-treated blocks 

are placed directly in contact with feeding termites. This 

sometimes requires some "instant carpentry." Often 

Coptotermes will seal off treated blocks if not placed into 

active feeding galleries, so other manipulations are 

necessary. For example, when these termites are detected in 

skirting boards, breaking open the outer wood and taping 

the treated blocks to the outer surface do not solve the 

problem, because, invariably, the termites will seal off the 

blocks, and no feeding occurs. Rather, cut through and 

remove the sound skirting board just ahead of the feeding 

termites. Place the treated blocks in the space left, and 

cover them with corrugated cardboard and tape. 

Assuming termite feeding occurs, allow about 3 to 4 

weeks before inspection and retrieval of the partially eaten 

blocks when no further termite activity can be detected. 

The blocks are returned to the laboratory and mirex is 

chemically removed from the partially eaten blocks and 

used again to impregnate new, wood-decayed blocks. All 

treated blocks are sealed in suitable containers until used. 

Place in Active Sheltertubes--When locating a termite 

sheltertube, break open a small portion (say about 25 mm) 

and verify the presence of active termites. If termite 

soldiers and workers are seen, remove a sufficient amount 

of sheltertube to allow treated blocks to be inserted 

between each of the broken ends of the sheltertube. Cover 

the blocks with corrugated cardboard, and tape in position. 

When placing several blocks in a sheltertube running 

vertically up a wall or stump (whether wood or brick 

construction), tape the blocks onto a suitable length of 

cardboard before placing between the broken ends of the 

active sheltertube. Allow 3 to 4 weeks for the termites to 

feed on the bait-blocks and distribute mirex throughout the 

colony. 

Outside Buildings 

Place in Active Galleries--When active galleries are 

found within infested trees, mirex-treated bait-blocks can 

be placed in conduit-box bait-containers and inserted into 

the trees (see section on conduit-box bait-container), and 

termite feeding can occur. Some of the most common 

places to find termite galleries are under timber structures, 

such as rail-sleepers and wood beams used in gardenscapes. 

On turning over these wood structures, the galleries may be 

seen running along the lengths of the timbers on the soil 

surface. Mirex-treated blocks can be laid along these 

galleries and the timber turned back in position. Again, 

allow up to 4 weeks before inspecting for termite activity. 

Assuming the blocks are attacked and partially eaten within 

this period, and no sign of live termites remains, one can 

assume a total eradication of that particular colony. The 

blocks may then be retrieved and reconstituted as 

mentioned previously. 

48 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Place in Active Sheltertubes--Careful inspection and 

digging around the building will often reveal active 

sheltertubes. Break into the tubes and place the mirextreated bait-blocks between the broken tubes, and cover 

with corrugated cardboard and some soil to protect the 

termites from other insect predators, such as ants. Allow 3 

to 4 weeks for termites to feed on the bait-blocks. The 

treatment period is similar to those suggested above. 

MIREX-SAWDUST-AGAR IN HOLLOW WOOD DOWELS 

M. darwiniensis and C. acinaciformis have been 

successfully controlled using mirex-sawdust-agar in hollow 

wood dowel baits in Queensland (Paton and Miller 1980) 

and New South Wales respectively. Small hollow wood 

dowels are manufactured, usually from hardwood 

dowelling. These are about 9 mm long, 10 mm in diameter 

with a 8-mm hole drilled out to a depth of 6 mm. Eucalypt 

sawdust is normally preferred, and this is impregnated with 

mirex. Up to 3 percent solutions are prepared for baits fed 

to M. darwiniensis. The mirex-treated dowels are easily 

inserted into active termite galleries and sheltertubes, and 

the contents eaten by the termites. This invariably leads to 

the death of the colony. 

However, as often happens in natural systems, C. 

acinaciformis in the vicinity of Sydney in New South 

Wales behave differently than their conspecifics in and 

around Melbourne, which is about 890 km away. 

Coptotermes in the Melbourne area have never fed on these 

baits when applied in and around buildings which have 

active termite infestations, yet this technique has been very 

successful in Sydney (J.A. Easey, pers. comm.). 

SUGGESTIONS FOR FUTURE RESEARCH IN BAIT 

TECHNIQUES 

Physiological and Behavioral Studies 

Given the differences in behavioral response to mirextreated baits of similar composition by C. acinaciformis in 

different geographic locations, such as between Sydney and 

Melbourne, it would be useful to understand why there are 

such differences. This requires long-term studies into the 

physiology and behavior of this species, which I suggest 

would be greatly assisted with a strong microbiological 

emphasis. I cannot envisage the pest control or insecticide 

industry addressing this question. Rather this work will 

need to be done by Government agencies and universities. 

Financial funding could be sought from industry. 

Attractancy Studies 

The problem encountered in use of baiting techniques 

against Coptotermes species has been the inconsistency of 

bait acceptance. Often baits placed within galleries, and to 

a lesser extent within sheltertubes, are not eaten and are 

even bypassed. Thus, it would be advantageous for the pest 

control industry to acquire baits that are always eaten when 

contacted. This will require long-term studies on suitable 

bait substrates, coupled with "attractancy studies." 

What is needed is a comprehensive monitoring of the 

termites' environment with respect to attractants from the 

wood substrates, attacked and unattacked substrate 

volatiles, leachates and chemical cues used by termites. 

This will call for collaboration with such specialists as 

biochemists, microbiologists, organic chemists, physicists 

and statisticians. 

Development of High-Technological Chemical Dusting 

Equipment 

In Australia the pest control industry still uses simple 

technology, such as dental puffers, to dust arsenic trioxide 

onto termites in galleries and sheltertubes. (A dental puffer 

is a hollow rubber ball, that is filled with a toxin, and a 

steel tube fitted in place from which to discharge the toxic 

powder). Although there are few "termite dusts" on the 

market, the development of our own clathrated inclusion 

compounds and other forms of encapsulated systems could 

well indicate a viable option in the near future. 

Refine the "Trojan Termite" Technique 

Include not only other termite species, but other 

potential slow-acting stomach poisons, such as boron 

compounds, oxidative inhibitors, insect growth regulators, 

and so on. 

Investigate the Gaseous Environment of Termites 

Apply gases into termite gallery systems that may cause 

death or slow collapse. Or "herd" termites into bait 

containers, and administer a suitable toxin. 

Use of Repellents 

Repellents might be used to aggregate termites into bait 

containers, or to cause them to move past "pre-treated 

surfaces" in order to acquire a lethal dose. 

SOME CONCLUDING REMARKS 

The consequences of banning or voluntary withdrawal 

of organochlorines as termiticides in North America will 

have far-reaching implications, particularly in termite 

control measures. In Australia, the restrictions on these 

chemicals have been greeted with mixed feelings. There is 

considerable public concern about the use of 

organochlorines because of the potential for persistent 

environmental contamination and consequent human 

exposure. The public perception has been one of health and 

environmental problems associated with past agricultural 

use and with the only currently approved use, as 

termiticides. 

The current administrative and legal systems (e.g., 

building regulations, Australian Standards) still specify 

organochlorine termiticides. However, events in North 

America and in Australia have helped to focus attention on 

pest control management systems that “target” termites more 

directly, such as baiting, rather than relying solely on 

chemical soil barriers. The reality of chemical barriers in 

Australia is that most pest control companies give only a 

one year warranty on chemical barriers. So it would seem 

that baiting is rapidly becoming a more acceptable control 

measure. The bait-block method of control using mirex 

(Beard 1974, and others) has proved successful in the past, 

the major drawback being that mirex is no longer 

registered for that use. 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 49 
Personally, I prefer the judicious use of such chemicals 

as mirex rather than the proposed soil chemical treatments 

using organophosphates and synthetic pyrethroids to 

eradicate subterranean termites from an existing building. 

Baiting techniques are not only well-targetted control 

measures, but are more "user-friendly" than soil chemical 

barriers. Human and environmental contamination are kept 

to a minimum given the nature of persistent insecticides. 

Although no data have been published on the amount of 

mirex residue to be found in the environment following the 

death of a termite colony, I would consider it negligible. 

Our experiments in the field indicate that C. lacteus 

(Froggatt) mound colonies of between 700,000 and 1 

million individuals die within 6 to 10 days after feeding on 

10 mirex-treated wood blocks impregnated with a 0.4 

percent mirex solution. This represents less than 2 g of 

active ingredient. 

Although I am aware of the history of mirex, we 

already permit its use under strict situations in Australia 

(see McFadden 1989). The end-point of our termite control 

measures is to make sure we kill the insects, and not 

people! Baiting technology, forming part of an integrated 

termite pest management strategy, will hopefully ensure 

this outcome. 

REFERENCES 

Beard, Raimon L. 1974. Termite biology and baitblock method of control. Connecticut Agricultural 

Experiment Station Bulletin 748, 19 p. 

Esenther, Glen R.; Gray, D.E. 1968. Subterranean termite 

studies in southern Ontario. Canadian 

Entomologist 100: 827-834. 

Esenther, Glen R.; Beat, Raymond H. 1974. Attractantmirex bait suppresses activity of Reticulitermes spp. 

Journal of Economic Entomology 67: 85-88. 

Esenther, Glen R.; Beal, Raymond H. 1978. 

Insecticidal baits in field plot perimeters suppress 

Reticulitermes. Journal of Economic Entomology 71:604-

607. 

Esenther, Glen R.; Beal, Raymond H. 1979. Termite 

control : Decayed wood bait. Sociobiology 4: 215-222. 

Esenther, Glen R. 1979. Termite bioassays show greatly 

varied tolerances to insecticides in bait blocks. Forest 

Products Journal 29: 55-56. 

French, John Richard Joseph. 1986. Termites and their 

economic importance in Australia. pp. 103-129. In: 

Vinson, S.B., ed. Economic impact and control of social 

insects. New York: Praeger; 421 p. 

French, John Richard Joseph; La Fage, Jeffery P. 1989. 

Termite standards questionnaire survey - Second 

Report. 20th IRG Meeting, Lappeenranta, Finland, Doc. 

No. IRG/WP/1395. International Research Group on 

Wood Preservation, Stockholm, Sweden. 

Lenz, Michael; Watson, John Anthony Linthorne; 

Barrett, Robert Aleyn. 1988. Australian efficacy data for 

chemicals used in soil barriers against subterranean 

termites. Canberra: Commonwealth Scientific 

and Industrial Research Organisation. 

McFadden, Peter. 1989. Mirex vs the Giant Termite - An 

information package. Department of Agriculture, 

Kununurra, Western Australia. 

Paton, Robert; Miller, Leigh. 1980. Control of Mastotermes 

darwiniensis Froggatt (Isoptera: Mastotermitidae) with 

mirex baits. Australian Forest Research 10: 249-258. 

Standards Association of Australia. 1974. Code of practice 

for physical barriers used in the protection of 

buildings against subterranean termites. Australian 

Standard. 1694-1974. 

Standards Association of Australia. 1986. Protection of 

buildings from subterranean termites - Chemical 

treatment of soil for buildings under 

construction. Australian Standard. 2057-1986. 

Standards Association of Australia. 1986. Protection 

of buildings from subterranean termites - Detection 

and treatment of infestation in existing buildings. 

Australian Standard. 2178-1986. 

50 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Population Suppression of Subterranean Termites by 

Slow-Acting Toxicants1 

Nan-Yao Su Rudolf H. Scheffrahn2 

Abstract: Historic background and the 


concept of slow-acting toxicants for 


population suppression of subterranean 


termites are reviewed. Information needed 


for development of bait-toxicants and 


studies needed to generate such informa­


tion are summarized. 


Current control measures for subter­


ranean termites rely exclusively on soil 


termiticides, primarily organophosphates 


and pyrethroids. They are used as toxic 


or repellent barriers between soil-borne 


termite colonies and structures requiring 


protection. La Fage (1986) estimated that 


soil termiticides are applied at a rate of 


ca. 390 kg/ha beneath treated structures 


compared to agricultural rates of 2.17 


kg/ha (Pimentel and Levitan 1986). The 


withdrawal from use of chlorinated hydro-


carbon termiticides in 1987 reflects 


public concern over the use of these 


persistent chemicals in highly populated 


urban environments. 


Despite the large quantities of 


pesticides used, soil treatments do not 


affect termite populations but only pro-


vide barriers to separate structures from 


soil-borne termites. Colonies of subter­


ranean termites, especially those of the 


Formosan subterranean termite (Coptotermes


formosanus Shiraki) which may forage as 


far as 100 m from the central nest, remain 


viable near the structures even after 


treatment (Su and Scheffrahn 1988a). 


Because of the inability of current con­


trol techniques to reduce existing subter­


ranean termite populations, the severity 


of infestations by C. formosanus in areas 


such as Honolulu, Hawaii, and New Orleans, 


Louisiana, has increased in recent years. 


1

Presented at the Symposium on Cur-


rent Research on Wood-Destroying Organisms 


and Future Prospects for Protecting Wood 


in Use, September 13, 1989, Bend, Oregon. 


2

Associate Professors, Ft. Lauderdale 


Research and Education Center, Institute 


of Food and Agricultural Sciences, Univer­


sity of Florida, Ft. Lauderdale, Fla. 


Researchers in the early 1900's first 


observed that the slow-acting arsenic 


dusts could be used to reduce colony 


populations of subterranean termites 


(Randall and Doody 1934). The principle 


of suppressing colony populations is to 


provide a means for individual termites to 


acquire a lethal dose of slow-acting 


toxicant at a given foraging site. The 


intoxicated individuals must not be so 


impaired at the onset of exposure that 


they cannot move away from the toxicant 


acquisition site to die. The slow-acting 


characteristic of a toxicant is particu­


larly important because accumulation of a 


large number of dead termites at the 


acquisition site will repel other nest-


mates from approaching the toxicant (Su 


and others 1982a). Ideally, the toxicant 


has to be nonrepellent to termites, or at 


least be masked by other agents to prevent 


avoidance behavior by the foraging ter­


mites. Under this premise, the toxicant 


can be incorporated into a bait (feeding 


acquisition) or tracking powder (contact 


and grooming acquisition). In this paper, 


we will primarily discuss the bait con­


cept. 


Beard (1974) suggested the use of 


bait toxicants as a possible strategy to 


eliminate established colonies of the 


subterranean termites, Reticulitermes spp. 


Dechlorane (mirex) baits have been used to 


suppress activity of field colonies of 


Reticulitermes in the United States 


(Esenther and Beal 1974, 1978), and to 


kill field colonies of an Australian 


subterranean termite, Mastotermes darwini­


ensis Frogg. (Paton and Miller 1980). Gao 


and others (1985) also reported successful 


field control of termite infestations with


mirex baits in China. 


Laboratory studies indicated that 


hydramethylnon (AmdroR

), avermectin B1 (Su 


and others 1987), A-9248 (Su and Schef­


frahn 1988b), sulfluramid (Su and Schef­


frahn 1988c), and insect growth regulators 


(IGRs) such as methoprene, fenoxycarb, and 


S-31183, have shown delayed toxicity 


against C. formosanus and the eastern 


subterranean termite, Reticulitermes


flavipes (Kollar) (Jones 1984, Su and 


others 1985, Haverty and others 1989, Su 


and Scheffrahn 1989). A field trial with 


hydramethylnon baits, however, resulted 


USDA Forest Service Gen. Tech. Report PSW-128. 1991. 51 
POPULATION SUPPRESSION OF SUBTERRANEAN TERMITES BY 

SLOW-ACTING TOXICANTS 

LABORATORY PHASE FIELD PHASE 

Figure 1--Studies needed to establish information for development 


of bait toxicants to suppress populations of subterranean ter­


mites. 


only in partial control of C. formosanus


colonies (Su and others 1982b). 


INFORMATION NEEDED FOR DEVELOPMENT OF A 


SLOW-ACTING BAIT 


Development of a bait toxicant re-


quires numerous, interconnected laborato­


ry and field studies followed by a rigor­


ous evaluation phase (Figure 1). 


Laboratory Phase


Toxicity and Lethal Time 


Oral or topical LD50 or LD95 should 


be calculated to estimate the gross 


quantity of toxicant needed for control of 


entire colonies. This information can also 


be used to compare the relative toxicity 


among toxicants. 


52 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
Lethal time of a toxicant is concen­


tration dependent. A bait toxicant should 


be used at a concentration that causes 


protracted behavioral impairment and 


latent mortality so that termites, having 


fed on bait, will disperse throughout 


their foraging territories before succumb­


ing to the toxicant. Su and others (1987) 


defined an effective lethal time 90%


(ELT90) as the amount of time required by


a fixed concentration of a toxicant to 


kill at least 90 percent of termites. 


ELT90 can be used to assess the feasibili­


ty of a candidate compound as a bait 


toxicant and to predict the time frame 


required for control. Lethal time (ELT90) 


of candidate toxicants can also be used to 


compare toxicants. 


Bait Acceptance 


In field trials, a bait must be 


competitive with other termite food re-


sources. Termites should not be repelled 


(Su and others 1982a) or their feeding 


deterred by bait additives (Su and Schef­


frahn 1988b). In the past both choice (Su 


and Scheffrahn 1988b) and no-choice bioas­


says (Scheffrahn and Su 1987; Grace, in 


press) were used to determine concentra­


tion-dependent feeding on treated sub­


strates. Table 1 summarizes interpreta­


tions of no-choice and choice bioassay 


under various hypothetical experimental 


outcomes. Although both no-choice and 


choice feeding bioassays can detect con­


centration-dependent repellency and feed­


ing deterrence, only a choice bioassay can 


determine that the toxicant-treated food 


source is more or less accepted by ter­


mites than identical untreated food sub­


strate. Because the behavioral responses 


of termites toward treated baits are 


concentration-dependent, it is vital that 


a choice bioassay be used to determine the 


acceptable concentration of a candidate 


toxicant before it is used in field 


trials. 


The two important characteristics, 


slow-acting and no feeding deterrence, are 


concentration dependent (Su and others 


1987 , Su and Scheffrahn 1988b). A de­


sirable toxicant should be accepted by 


termites at efficacious concentrations to 


cause significant delayed mortality. An 


index combing these three parameters, 


concentration, delayed mortality and 


feeding deterrence, therefore, can be used 


to evaluate the potential of a toxicant. 


We propose here a Bait Toxicant Efficacy 


(BTE) index which is defined as the quo­


tient of bait acceptance threshold concen­
 tration (BATC) and the threshold concen­


tration to produce significant delayed 


mortality (DMTC); namely BTE = BATC/DMTC. 


A toxicant with BTE • 1 (such as pyre­


throid, Su and others 1982a) cannot be 


used in a bait, while BTE > 1 indicates a 


bait-toxicant potential. Using this 


criterion, BTE index for the slow-acting 


A-9248 (dihaloalkyl arylsulfone) against 


C. formosanus was 3 (600 ppm [BATC] ÷ 200 


ppm [DMTC]) (Su and Scheffrahn 1988c). 


Similarly, BTEs' for mirex and sulfluramid 


against C. formosanus were 9 (90 ppm ÷ 10 


ppm) and 2.5 (10 ppm ÷ 4 ppm), respective­


ly. BTE values for sulfluramid (30 ppm ÷ 


18 ppm) and mirex (15 ppm ÷ 9 ppm) are 


identical (1.7) against R. flavipes (Su 


and Scheffrahn, in press). 


Dye Marker Evaluation 


Dye markers are useful to determine 


foraging territories and to estimate 


foraging populations of subterranean 


termite colonies. There has been criti­


cism of the application of the capture-


recapture technique for population estima­


tion of social insects (Ayre 1962). The 


criticism was based on the argument that 


individuals in insect colonies do not 


distribute randomly in space, and thus one 


of the basic assumptions of mark-recapture 


model is violated. For example, most of 


the younger (1-2 instar) termites do not 


move to distant foraging sites. Baroni-


Urbani and others (1978), however, pointed 


out that the mark-recapture technique is 


often the only practical method for study­


ing the population dynamics of some in-


sects. This is especially true for the 


cryptobiotic insects such as subterranean 


termites. 


Su and others (1984) demonstrated 


that C. formosanus workers chose foraging 


sites at random; thus all of the released 


marked foragers should distribute evenly 


within the population. Moreover, only 


foragers can be captured using the pre-


scribed trapping system (Su and others 


1984, Su and Scheffrahn 1986, 1988a). The 


mark-recapture technique, thus, is an 


effective method of quantifying the popu­


lations and movements of subterranean 


termite foragers. 


Sudan Red 7B (or Oil Soluble Red 7B) 


was first used by Lai and others (1983) to


estimate the size of colonies of C. formo­


sanus in Hawaii. Laboratory studies 


showed that Sudan Red 7B was not trophal­


lactically transferred by _C. formosanus


(Su and others 1983) or R. flavipes (Su and 


others 1988). This dye was subsequently 


adopted as the standard dye to determine 


foraging territory and population of C. 
 formosanus in Florida (Su and Scheffrahn 


1988a), and R. flavipes in Toronto (Grace, 


in press). Jones (in press) also used 


Sudan Red 7B to define foraging boundaries 


USDA Forest Service Gen. Tech. Report PSW-128. 1991. 53 
Table 1. 	Potential results of no-choice and choice bioassay and data interpreta­


tions. 


Results Interpretations 

Feeding compared Mortality compared


to control to control 
 No choice bioassay
 Choice bioassay 


_ = 


_ > 


< = 


> 


> = 


> > 


Not feeding deterrent 


Not repellent 


Not toxic 


(UNDESIRABLE) 


Not feeding deterrent 


Not repellent 


Toxicant 


(DESIRABLE)* 


Feeding deterrent or 


repellent 


Not toxic 


(UNDESIRABLE)** 


Feeding deterrent or 


repellent or 


Mortality due to 


contact toxicity? 


or starvation? 


(VERY UNDESIRABLE) 


Feeding stimulant 


Not toxic 


(Potential additive-


masking agent) 


Feeding stimulant 


Toxicant 


(VERY DESIRABLE) 


Non-preference 


Not toxic 


(UNDESIRABLE) 


Non-preference 


Toxicant 


(VERY DESIRABLE) 

Unpreferred 


substance 


Not toxic 


(UNDESIRABLE) 


Unpreferred 


substance 


Contact toxicant 


(VERY UNDESIRABLE) 


Preferred 


substance 


(Potential additive 


masking agent) 


Preferred 


substance 


(IDEAL BAIT 


TOXICANT) 


* Theoretically, this scenario should not occur because higher mortality would 


result in over all lower feeding. 


** Theoretically, this result cannot be obtained because lower feeding would 


eventually cause higher mortality by starvation. 


of Heterotermes aureus (Snyder) in Arizo­


na. Sudan Red 7B, however, does cause 


mortality of C. formosanus (10-15 percent)


during staining, and causes a latent 


mortality of R. flavipes (30-80 percent 


mortality at 2-8 weeks after being stained 


with 0.5 percent dye for 10 days) (Su and 


others 1988). 


In a laboratory screening test, we 


(Su and others, unpublished data) have 


identified two dyes, Nile Blue and Neutral 


Red, that have even better potential than 


Sudan Red 7B as markers for C. formosanus


and R. flavipes. Currently, we are 


testing the color fastness of these dyes 


in mixed groups of marked and unmarked 


foragers. 


Field Phase


Foraging Population Survey 


To adequately evaluate results of 


field trials, foraging activity, foraging 


population size, and foraging territory of 


subterranean termites must be monitored 


before the introduction of a bait. 


Esenther and Beal (1974, 1978) reported 


54 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
successful suppression of field colonies 


of Reticulitermes spp. with mirex baits. 


However, the activity of these field 


populations of Reticulitermes had not been 


monitored before bait application. It is 


uncertain whether the field populations 


were repelled from the test site or wheth­


er the populations were indeed suppressed.


Ideally, the colony activity should 


be monitored for a few years before the 


application of bait toxicants. The proc­


ess of marking, counting, releasing, and 


recapturing is a laborious task. A more 


sophisticated model than the simple Lin­


coln index for estimating the foraging 


population provides more information with 


the same effort. The weighted-mean model 


using a multiple mark-release procedure 


enabled us to obtain estimates with a 


relatively low standard error (Su and 


Scheffrahn 1988a). However, the procedure 


required three months to complete. More-


over, it takes another three months for 


the last stained termites to totally lose 


their marking before another cycle of 


multiple mark-release procedures can be 


initiated. Because of foraging inactivity 


during cool months in southeastern Flori­


da, the mark-release program is implement­


ed from April to November. Realistically, 


therefore, only one mark-release program 


per colony is possible per annum. 


Although the size of the foraging 


populations can be estimated only once 


annually, foraging activity can be moni­


tored all year by counting the number of 


termites in the traps and measuring wood 


consumption during monthly or bi-monthly 


trap changes. Although the boundary of a 


foraging territory is defined before bait 


application, change in foraging activity 


and territory should be monitored through-


out the bait toxicant evaluation period. 


Bait Application 


The trapping system described by Su 


and Scheffrahn (1986) can be used for bait


field trials. Trap stations within a 


colony monitoring system should be select­


ed at random to receive toxicant baits, 


while the others receive similar baits 


without toxicant. The difference in 


activity (number of termites and wood 


weight loss) between treated and untreated 


stations then can be compared to detect 


termites' preference in visiting baits 


with or without toxicant. 


In our field trials (Su and others, 


unpublished data), we use a toxicant bait 


composed of six pieces of pine (Pinus


spp.) board (7 cm by 13 cm by 2 cm thick), 


three of which were vacuum impregnated 


with toxicant while the others were treat­


ed with impregnation solvent only. The 


dry weight of each wood piece was deter-


mined before bait assembly. After the 


baits were exposed to termites, the wood 


weight loss of toxicant-treated and sol-


vent control boards was compared to 


ascertain termite feeding preferences. 


Evaluation 


During the field trial, the foraging 


preference by termites between treated and 


untreated sites (i.e., number of termites 


collected per trap) and feeding preference 


between treated and untreated wood pieces 


should be monitored. The mark-release 


program, which would have to be interrupted 


during the trial because of the potential 


negative effects of the dye marker, should 


be reinstituted after the termination of 


the bait toxicant exposure to determine 


the effects of the bait toxicant on the 


foraging populations. 


ACKNOWLEDGMENTS 


We thank Michael I. Haverty and Sandy 


Young for reviewing the manuscript. This 


is Florida Agricultural Experimental 


Station Journal Series No. N-00206. 


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USDA Forest Service Gen. Tech. Report PSW-128. 1991. 57 
-------------------------------------------------------------------------- 

--------------------------------- 

How Do We Advise the Pest Control Industry in the 

Post-Organochlorine Era?1 

J.R.J. French2 

Abstract: Given the banning of organochlorines for use as 

termiticides in North America, and with the possibility of 

such bans occurring in future in Australia and elsewhere, 

how do we as entomologists advise the pest control industry 

in termite control? A brief historical review of pesticide 

bans and the relevance of these bans to the present 

situation are discussed. Suggestions are offered for 

entomologists to pursue an integrated pest management 

approach to termite control based on sound ecological 

parameters and social priorities. 

Before attempting to offer suggestions as how best to 

advise the pest control industry in the post-organochlorine 

era, I think it is as fruitful to understand the social and 

political context in which bans on pesticide use have been 

imposed historically, as to offer resolutions that may 

receive the same treatment in the long-term. 

So, how did bans on pesticide use come about? Were they 

imposed by scientists in government and industry? It would 

seem that was not the case. Before 1962, many scientists 

were expressing great concern as to the side-effects, the 

indirect effects, and the long-term effects of 

organochlorine pesticides. They were not only concerned 

with the target organisms themselves, but with other 

organisms, as the pesticides moved through the 

environment, following food chains as predator ate 

predator, and acting on people. 

Egler (1964) considered that these scientists were 

ridiculed or ignored or silenced in a variety of ways, even 

by their own colleagues, and especially by the chemical 

industry and its chief advocates in the U.S. Department of 

Agriculture and the U.S. Food and Drug Administration. 

But their work and concerns were not lost to society. There 

came a change. 

This change came in the form of a book, Silent Spring, 

written in 1962 by Rachel Carson, a marine biologist. As 

Ehrlich and others (1977) pointed out, "it is true that there 

were a few factual errors in Silent Spring, but in many 

ways Rachel Carson underestimated the hazards of DDT 

and certain other organochlorines. Nevertheless, she 

succeeded in awakening the public - and did so in a way 

that a more technical and highly documented book like 

Robert L. Rudd's (1964) Pesticides and the Living 

1Presented at the Symposium on Current Research on 

Wood-Destroying Organisms and Future Prospects for 

Protecting Wood in Use, September 13, 1989, Bend, 

Oregon. 

2Principal Research Scientist, CSIRO, Division of Forestry 

and Forest Products, Graham Rd, Highett, Vic. 3190. 

Australia. 

Landscape could not. Rudd, a zoologist, came to many of 

the same conclusions that were presented in Silent Spring, 

but because his book was not addressed to the general 

public it did not engender the level of attack that was 

directed toward the Carson book." 

In the opinion of Ehrlich and others, "no biologist has 

made a greater contribution to humanity in this country 

than Rachel Carson. And recent events and government 

decisions have fully justified her position." 

Soon after the U.S. Environmental Protection Agency 

(EPA) was created in 1970, it was given responsibility for 

the registration and regulation of pesticides. Litigation by 

the Environmental Defense Fund produced a court order 

early in 1971 for EPA to issue public notices of 

cancellation of the registration of DDT and to review DDT 

for suspension. The notices of cancellation for DDT, as 

well as aldrin, dieldrin, mirex, and the herbicide 2,4,5-T, 

were, of course, appealed. After lengthy hearings, EPA 

banned DDT for almost all uses in 1972. It found that DDT 

"posed an unacceptable risk to man and the environment." 

Restrictions were also placed on mirex. A ban followed a 

few years later. 

Concern was expressed that banning of organochlorines 

would lead to increased immediate mortality from pesticides 

because the organophosphate compounds that would 

replace DDT have a higher acute toxicity even though they 

are much less persistent and presumably present a 

relatively small long-term risk. However, about 1969, 

occupational deaths from pesticides (mainly 

organophosphates) occurred at the rate of about 12 per year 

nationally. There was no sign of an increase into the mid 

1970's (Ehrlich and others 1977). 

The direct threat to humanity by organochlorines is 

difficult to assess (Anon 1989b). At present, however, it 

appears that, as alarming as the direct threat may be, the 

indirect threat is much more serious. These compounds 

have the potential for irreversibly damaging the capacity of 

ecological systems to supply those essential services without 

which civilization cannot persist (Ehrlich and others 1977). 

In 1987, the EPA restricted the uses of organochlorines 

as termiticides, permitting only the use of chlordane as a 

soil barrier. Alternatives such as the organophosphates 

(chlorpyrifos [Dursban], and isofenphos [Pryfon 6]) and 

synthetic pyrethroids (cypermethrin [Demon], permethrin 

[Dragnet], permethrin [Torpedo], and fenvalerate [Tribute]) 

have been recommended by the EPA. These are currently 

the termiticides of choice by the pest control industry in 

the United States (Mix 1988). 

These events have not unfolded in a "neutral 

environment," but rather, as a result of persistent political 

challenging by scientists, environmental groups, such as 

the National Coalition Against the Misuse of Pesticides 

(NCAMP), consumer and union groups, and the public of 

58 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
----------------------------------------------------------------- 

----------------------------------------------------------------- 

------------------------------------------------------------------------------------- 

-------------------------------------------------------------------------------------

our society's pesticide use. The National Academy of 

Science in the United States has been concerned with the 

impact of regulation on the development of new 

technologies to replace the conventional broad-spectrum 

chemicals that have dominated the pest control scene since 

1950. Whether or not those required technologies will be 

generated within the chemical industry remains uncertain, 

and some think, unlikely (see Ehrlich and others 1977). 

Now in 1989, we have the voluntary cancellation by 

the insecticide manufacturers of their organochlorines used 

as termiticides in the United States. In Australia, there has 

been mounting public concern over environmental and 

public health issues surrounding the use of these pesticides. 

Recent publicity in connection with pesticide residues in 

beef and an incident at the Streaky Bay School in South 

Australia following application of aldrin as a termiticide 

(Anon 1989a) has focussed attention on organochlorines in 

particular. Currently, all organochlorines are banned in 

South Australia (Anon 1989b), and in most other Australian 

states, for all purposes except as termiticides. The question 

being asked by some scientists and members of the pest 

control industry in Australia, is -"will organochlorines be 

banned for all uses, as in the United States?" 

Personally, I predict a similar trend in Australia in the 

not too distant future. There is a strong upswell of feeling 

by interest groups, such as the Total Environment Centre 

in Sydney, unionists in all states, and numerous 

environmental groups, to have these compounds completely 

banned. There has been wide publicity in the media on the 

topic, and the public perception has been one of health and 

environmental problems associated with past agricultural 

use and with the only currently approved use, as 

termiticides (Anon 1989b). Notwithstanding the reaction of 

a pesticide proponent in the pest control industry, terming 

such critics of pesticide use as "toxic terrorists" (Meadows 

1988), the problem of chemical pollution will not readily 

diminish given current economic values. 

INTERNATIONAL OVERVIEW OF TERMITE 

CONTROL 

In May 1987, the International Research Group on 

Wood Preservation (IRGWP) conducted a survey of its 55 

member countries to ascertain the economically-important 

termite species in the various zoogeographical regions, their 

damage ranking to timber-in-service, the chemicals used in 

control methods, and the status of the termite standards in 

the respondent countries. Table 1 summarizes the 

information collected in the survey so far (French and La 

Fage 1989). 

Countries that have standards for chemical control of 

termites include Canada, France, Greece, India, Italy, 

Japan, Spain, Australia, and the United States. Nigeria is 

presently preparing a standard. Organochlorines, 

organophosphates and synthetic pyrethroids are the most 

commonly used chemicals. Arsenical preparations are used 

in Fiji, Greece, Spain, Australia and Uganda. Japan is one 

of several countries that use gas fumigants as termiticides. 

Australia, Japan, Canada and the United States also register 

organophosphates as termiticides. 

The methods of application were found to vary 

considerably between countries. The common practice of 

applying a chemical barrier over the entire exposed surface 

area under a pier-type building is carried out in India, 

Japan, Nigeria and the United States. The treatment of soil 

adjacent to piers and supports, however, is the preferred 

procedure for most countries. The issue of compulsory soilbarrier termiticide treatment to new buildings was not 

directly addressed, though Indonesian authorities stated 

they do not insist on this approach, unlike most local 

authorities in Australia. Some countries, such as Fiji and 

Italy, do not carry out soil-barrier treatments. Treatment of 

existing buildings is done in most countries only as a 

consequence of infestation. However, Japan undertakes retreatments every 5-10 years, probably because of the lower 

persistent organophosphates used. In Australia, many pest 

control companies carry out yearly soil-barrier treatments 

using organochlorines, although this is not stipulated in any 

Australian Standard. However, such "re-treats" are regular 

business practices in rural areas. 

Table l-- The major termiticides used in termite control 

Region Country Termiticides used 1 

--------------------------------------------

OC OP SP GAS AS O 

Ethiopian Ghana + + + + + + 

Nigeria + WP 

South Africa + WP 

Tanzania + + 

Uganda + + 

Palearctic China (Nanjing) + + + Mirex 

France + + + + 

Greece + + + 

Israel + + + 

Italy + + + 

South Korea + + + 

Spain + + + + 

Yugoslavia + 

Oriental India + + + WP 

Indonesia + + + 

Japan + + WP 

Phillippines + 

Australian Australia + + + + + Mirex 

New Zealand + 

Hawaii and Fiji + + + 

Oceanic Is. Hawaii + + + + NCB 

Nearctic Canada + + 

USA + + + IGR 

Neotropical Bolivia + + 

Chile + + 

Columbia + + + 

Uruguay + + 

1OC = Organochlorine; OP = Organophosphate; SP = Synthetic pyrethroid; 

GAS = Fumigation; AS = Arsenicals; O = Other; IGR = Insect Growth 

Regulator; NCB =Non-chemical termite barrier; WP = Wood preservative 

treatment. 

No country appears to have formulated specialized 

standards for drywood termite control apart from 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 59 
recommending fumigants, as in North America and 

Australia. Yet in the Ethiopian, Hawaiian and Oriental 

regions, the risk of drywood termite damage exceeds that 

of subterranean or dampwood termites. 

PROPOSED TERMITICIDES AND TERMITE CONTROL 

METHODS 

Over the years many termiticides and termite control 

methods have been proposed worldwide, but in this paper 

the focus is on those applied in developed countries 

(French 1986, Mauldin 1986, and Lenz and others 1988). 

Assuming that the organochlorines are to be banned as 

termiticides, then the proposed termiticides of the future 

may be divided into two main groups, namely, pretreatments and post-treatments. 

Pre-treatments 

Pre-treatments are complete or partial chemical soilbarrier treatments for buildings under construction. The 

chemicals proposed are organophosphates, synthetic 

pyrethroids, brominated hydrocarbons, carbamates, and 

slow-release formulations of these compounds. An 

alternative delivery system ("Peacock system") of underslab 

perforated piping has been promoted in Hawaii, in which 

termiticides (organophosphates) are pumped in under 

pressure from an external servicing port. Other pretreatments include physical barriers and wood preservatives 

(such as boron compounds, copper-chromium-arsenic, light 

organic solvent preservatives, fluorinated lipids, and 

sulphones). 

Post-treatments 

Arsenic trioxide, used as a dust, is the only effective 

termiticidal use of arsenicals in Australia. It is legally and 

commercially available in Australia and the amount per 

treatment is small (ca. 3-5 g to eradicate a termite colony 

of > 1 million individuals). 

Mirex, in the bait-block method, is effective when 

used for remedial treatments directed towards Coptotermes 

and Reticulitermes spp. This insecticide is registered for 

use in three states in Australia against the Giant Northern 

termite, Mastotermes darwiniensis Froggatt, and registration 

is being sought in Victoria and New South Wales for 

control of Coptotermes acinaciformis (Froggatt). 

Fumigants, such as methyl bromide, are used in 

remedial treatments, particularly against drywood termites. 

However, exposing localized drywood termite colonies to 

heat and cold (using liquid nitrogen) may also offer a 

measure of control (Forbes and Ebeling 1986). 

Other potential termiticides may be offered in baitblocks and baiting systems. For example, insect growth 

regulators, including juvenile hormone analogs and chitin 

synthesis inhibitors, boric acid, and amdro could be 

incorporated into bait-blocks. The latter is a non-repellent 

delayed-action termiticide. If bait systems are used, large 

aggregations of termites can be exposed to small but direct 

amounts of termiticides, such as arsenic trioxide, amdro, 

boric acid, mirex, and inclusion compounds containing 

toxins, and allowed to return to the colony and so transmit 

the toxin. 

ALTERNATIVES TO CHEMICAL TERMITICIDES 

Biological Control 

Different methods of biological control exist, and 

include: bacteria, fungi, protozoa, nematodes, natural 

predators, natural enemies or competitors, pheromones, 

attractants, repellents, and insect growth regulators. 

However, many of these biological control agents are, at 

present, beyond the scope of practical application for the 

average pest control operator in Australia. Insect growth 

regulators and other chemical analogs would seem to have 

more commercial promise than organisms such as bacteria, 

fungi, nematodes, and natural predators. I have 

experimented with the natural enemies or competitors of 

Coptotermes, and call them "trojan termites." These are 

termites, usually of the same genus, but different species, 

that are collected from another colony. They are taken to 

the infested building, and dusted with a suitable toxin such 

as arsenic trioxide, then released into the active galleries of 

the termite species attacking the building timbers. When 

the two termite groups meet, they fight, and thus help to 

pass on the poison through the colony originally attacking 

the building, which subsequently leads to the death of the 

termite colony. 

Although biological control of insect pests is 

increasingly being used in agriculture due to (1) pesticide 

resistance, (2) a growing awareness of probable health and 

environmental risks associated with using chemical 

pesticides, and (3) the financial costs of chemical control, 

some barriers do exist in refining such control methods. 

Biological control products are usually less stable 

compared to organic chemicals. Significant evaluation is 

also required to ensure that live biological controls do not 

have unintended ecological consequences. 

There are large costs in screening potential biological 

agents prior to obtaining registration. In Australia as of the 

1 July, 1989, the Federal Government now charges $20,000 

to register a new chemical product. This will tend to 

preclude small companies from entering the market, even if 

their products are environmentally superior to what is 

already registered. 

But there is a balance of forces between what society 

demands in insecticide selectivity and what society is 

prepared to pay for, though this balance is changing with 

increasing restrictions on the use of chemical insecticides. 

Biological control will probably become more important in 

the future, with the extent of development determined by 

economic forces. 

Physical Barriers 

Ant caps and shields 

Ant caps are metal shields which are placed on the top 

of each pier beneath the building, and along the top of all 

foundations. However, because of problems in building 

construction, such barriers are readily bypassed by 

subterranean termites. These barriers work fine if the 

60 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
buildings are regularly inspected, because they force the 

subterranean termites to build shelter tubes over them, thus 

exposing their presence to the inspector. 

Non-Chemical Barriers 

In 1957, Ebeling and Pence reported on the 

relationship of particle size to the penetration of 

subterranean termites through barriers of sand or cinders. 

This type of non-chemical barrier has recently been 

perfected in Hawaii to protect structures from attack by 

the Formosan termite, Coptotermes formosanus Shiraki 

(Tamashiro and others 1987). On the mainland United 

States, Ebeling and Forbes (1988) have applied for patent 

protection on the use of sand barriers. Laboratory and field 

experiments in Australia have shown similar relationships 

by challenging Coptotermes species with granite and basalt 

substrates (French 1989). 

ADVICE TO THE PEST CONTROL INDUSTRY--A 

VIEWPOINT 

The banning of DDT, for example, would no doubt be 

a laudable victory in the war to save the environment, but 

it would be disastrous to mistake such a victory as winning 

the war. The profound changes necessary to save the 

environment and society will not be made easily. Powerful 

opposition can be expected from economic interests. So 

how can scientists, particularly entomologists, assist in this 

arena and facilitate a more ecological approach to insect 

pest management? 

First, entomologists need to think and act ecologically. 

They need to accept that the ideological status of ecology is 

that of a resistance movement. Its Rachel Carsons and Aldo 

Leopolds are subversive (as Sears (1964) called ecology 

itself). They challenge the public or private right to pollute 

the environment, to systematically destroy predatory 

animals, to spread chemical residues indiscriminantly, to 

meddle chemically with food and water; they oppose the 

uninhibited growth of human populations, the extinction of 

species of plants and animals, the domestication of all wild 

places, large-scale manipulations of the atmosphere (e.g., 

greenhouse effects) or the sea, and most other purely 

engineering or technological solutions to problems of and 

invasions into the organic world. 

Second, their task is to inculcate basic ecological 

attitudes in the government, the pest control industry, and 

the public. They have to teach the population simple but 

basic ecological notions: a finite world cannot support or 

withstand a continually expanding population and 

technology; there are limits to the environmental sinks; 

ecosystems are sets of interacting entities, and there is no 

"treatment" which does not have "side effects." 

Third, as ecologists, entomologists will have a central 

role in advising on the management of the environment. 

Thus, good management will depend on rather long-term 

studies of particular areas, since ecological situations are 

dependent both on time and locale. These two features also 

ensure that there will be a sizeable lag-time between posing 

the question and receiving the ecological advice, and a 

major job of the entomologists will be to make the 

existence of such lags known to the policy-makers. 

Entomologists will have to apply technology. For example, 

integrated pest management systems will surely replace 

chemical control alone. 

Fourth, entomologists need to ensure that the scientific 

establishment must become more closely regulated by 

collective decision-making processes. Upgrading the 

educational system (by words and deeds) and revising the 

role of mass media would prepare the public to play a 

more active role in directing scientific activities. 

Finally, as Pirages and Ehrlich (1974) concluded, social 

priorities must be drastically altered to turn science inward 

to the study of people, their values, and their institutions. 

This area of inquiry will be vital to future survival, given 

the need to redirect human aspirations and consumption 

patterns. If social expectations and behavior are not altered, 

even the most earnest technological efforts will be unable 

to keep pace with growing human demands. 

REFERENCES 

Anon 1989a. Report of the Ministerial Scientific and 

Advisory Committee: Aldrin contamination, Streaky 

Bay area school. South Australian Health 

Commission, Adelaide, 186 p. 

Anon 1989b. Report of the Controlled Substances Advisory 

Council on the consequences of banning the use of 

aldrin, dieldrin, chlordane and heptachlor as 

termiticides in South Australia and an investigation 

of alternatives. South Australian Health Commission, 

Adelaide, 162 p. 

Carson, Rachel. 1962. Silent spring. Boston: Houghton 

Mifflin. 

Ebeling, Walter; Pence, R.J. 1957. Relation of particle size 

to the penetration of subterranean termites through 

barriers of sand or cinders. Journal of Economic 

Entomology 50(5): 690-692. 

Ebeling, Walter.; Forbes, C.F. 1988. Sand barriers for 

subterranean termite control. IPM Practitioner 10(5): 

1-6. 

Egler, Frank E. 1964. Pesticides - in our ecosystem. 

Bioscience 52: 110-136. 

Ehrlich, Paul R.; Ehrlich, Anne H.; Holdren, John P. 1977. 

Ecoscience: Population, resources, environment. San 

Francisco: W.H. Freeman & Co., 1051 p. 

Forbes, C.; Ebeling, Walter. 1986. Update: liquid nitrogen 

controls drywood termites. IPM Practitioner 8(8): 1-4. 

French, John Richard Joseph. 1986. Termites and their 

economic importance in Australia. In: Vinson, S.B., 

ed. Economic impact and control of social insects. 

New York: Praeger; 103-129. 

French, John Richard Joseph. 1989. The case for nonchemical termite barriers in termite control? 20th 

IRG Meeting, Lappeenranta, Finland. Doc. 

IRG/WP/1381. International Research Group on 

Wood Preservation, Stockholm, Sweden. 

French, John Richard Joseph.; La Fage, Jeffery P. 1989. 

Termite standards questionnaire survey - Second 

Report. 20th IRG Meeting, Lappeenranta, Finland. 

Doc. No. IRG/WP/1395. International Research 

Working Group on Wood Preservation, Stockholm, 

Sweden. 

Lenz, Michael.; Watson, John Anthony Linthorne.; Barrett, 

Robert Aleyn. 1988. Australian efficacy data for 

chemicals used in soil barriers against subterranean 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 61 
termites. Canberra, Australia: CSIRO, Division of 

Entomology, Tech. Paper No. 27. 

Mauldin, Joseph K. 1986. Economic importance and 

control of termites in the United States. In: Vinson, 

S.B., ed. Economic impact and control of social 

insects. New York: Praeger; 130-143. 

Meadows, Peter. 1988. G'day mates and give'em hell. Pest 

Control (January): 28. 

Mix, Jerry. 1988. Leading today's termiticide parade. Pest 

Control (March): 40-41. 

Pirages, Dennis C.; Ehrlich, Paul R. 1974. Ark II. Social 

response to environmental imperatives. San Francisco: 

W.H. Freeman & Co., San Francisco. 344 p. 

Rudd, Robert L. 1964. Pesticides and the living landscape. 

University of Wisconsin Press; Madison. 

Sears, Paul B. 1964. Ecology - a subversive subject. 

Bioscience 14: 11. 

Tamashiro, Minoru.; Yates, Julian R.; Ebesu, Robert H.; 

Yamamoto, Robert T. 1987. The Formosan termite: 

Hawaii's most damaging insect. Hawaii Architect 

16(12): 12-14,40. 

62 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
DISCUSSION 

What follows represents the minutes of the workshop on 

wood-destroying organisms held in Bend, Oregon, September 

14, 1989. The theme of the workshop was the state-of-the art of 

control of wood destroying organisms and the needs for further 

research on wood-destroying organisms. The agenda for the 

session was organized by W. Wayne Wilcox and Michael I. 

Haverty. 

FUTURE OF WOOD PRODUCTS 

PATHOLOGY 

Wayne Wilcox outlined what he thinks are the priorities for 

education and research on wood products pathology: 

• Education of the user (designers, builders, general public 

or building owners) to reduce the losses due to decay. 

• Development of nondestructive techniques to evaluate 

wood decay in structures (also techniques for diagnosing 

infestations by active wood-destroying insects in structures). 

• Development of new regimes for protecting wood from 

biodegradation in the absence of toxicants, i.e., biological 

control and modifications of wood chemistry. 

• Evaluation of third-generation wood preservatives, and 

their effects on nontarget organisms. A variety of compounds or techniques will be used in specific applications. 

In the future it will be much more expensive to prevent 

wood decay. 

• Increased knowledge of wood-destroying fungi—biological, taxonomic, phylogenetic—and of specialization of 

fungi in different environments. 

Harold Burdsall discussed pathology research at the Forest 

Products Laboratory, Madison, Wisconsin. 

• Institute for Microbial and Biochemical Technology. Investigations of biodeterioration or biodegradation as positive uses of wood-degrading organisms, lignin degradation, wood pulping, pretreatments to reduce the energy 

needed in pulping, fungi to break down toxic wastes, and 

fungi to clean up mill effluent. 

• Biodeterioration of Wood. Basic biochemical mechanisms 

of decay, serological examinations, and mechanisms by 

which enzymes are delivered by fungi taken to wood 

tissues containing lignin for wood decomposition. 

• Center for Forest Mycology Research. Taxonomy of fungi, 

Armillaria root rot, serological investigations of Phlebia 

for diagnosis of species, and other ways to distinguish 

species. This group is developing a chicken egg technique 

as an immunological test for identification of species or 

strains. They inject fungal tissue into each breast and each 

leg of a chicken and repeat the process in 1 week. This 

results in an increase in diagnostic proteins in the eggs after 

approximately 3 to 4 weeks. 

Elmer Schmidt discussed the most recent (1989) meeting of 

the International Research Group on Wood Preservation, 

Stockholm, Sweden. This organization is a forum for new ideas 

on wood preservation and wood-destroying organisms. The 

general areas are: (1) biological problems (fungi and insects), (2) 

testing methods (bioassays), (3) preservation of marine timber, 

and (4) wood preservation. 

FUTURE OF WOOD PRODUCTS 

ENTOMOLOGY 

Michael Haverty outlined what he thought were the key 

issues facing researchers in wood products entomology: 

• Continued assessment of new soil termiticides with advances in their application for increased efficacy and 

longer effective life. 

• Assessment of non-chemical, physical barriers for protection before construction begins. 

• Better understanding of the taxonomy of the economically 

important termites in the United States, primarily 

Reticulitermes and Coptotermes. 

• Acceleration of research on foraging behavior and related 

colony demography to increase our understanding of feeding behavior of termites. 

• Increasing our understanding of the physiology and behaviors involved in feeding by subterranean termites: 

attractancy, repellency, and seasonal trends. 

• Study of the biochemical mechanisms related to repellency to enhance protection of structures and counter the 

avoidance of toxic baits. Also continued study of the 

behavioral/biochemical basis of intra- and interspecific 

agonistic behavior in termites. 

• Continued refinement of the bait/toxicant approach to 

subterranean termite control based on technological advances from areas above. 

• Reassessment of mirex as the toxicant in termite baits. 

Joe Mauldin discussed the use of borates as preventative 

treatments. Jeff Morrell (Oregon State University), Terry 

Amburgey (Mississippi State University), and Lonnie 

Williams (USDA Forest Service, Gulfport) are the primary investigators. Borates can be applied by diffusion 

into green (wet, moist) wood. High concentrations of 

borates on the wood surface diffuse into the center of the 

wood. Pressure treatment may be used after the wood is 

dry. There is also the possibility of injecting low concentrations of borates into live trees in hopes of protecting 

wood after harvest. These treatments are effective against 

termites, beetles, and many fungi. The treatment is tarUSDA Forest Service Gen. Tech. Report PSW-128. 1991. 63 
geted for woods which will be protected from moisture, 

because borates can be leached from the wood. Effects on 

nontarget organisms are a concern if high concentrations 

of borates are misused. Borates are the major ingredients 

in household products such as Visine and 20-mule-team 

Borax detergent. 

Joe Mauldin also discussed research projects by the scientists at the USDA Forest Service laboratory in Gulfport, Mississippi, directed at methods of protecting wood in use. 

• Borates (see above). 

• Wood extractives (natural preservatives in woods) are 

being investigated by Skip McDaniel. Chemicals are extracted, isolated, and their toxicity measured. Most of the 

toxic chemicals identified thus far are terpenes and alkaloids. 

• Susan Jones is investigating baiting systems in Arizona for 

Heterotermes and in Mississippi and Florida for 

Reticulitermes. Some of the borate compounds appear to 

have promise in bait systems. 

• Traditional termite control with soil toxicants is continuing to be developed by Brad Kard. In the laboratory he 

screens insecticides to find those with promise for long life 

in soil as termite barriers. He conducts his field studies at 

test sites all over the United States. Brad is also fieldtesting plastics with slow-release pesticide and crushed 

basalt as termite barriers. 

Michael Haverty commented on an observation he (and Joe 

Mauldin and Nan-Yao Su) made in Southeast Asia. In the urban 

areas in Southeast Asia, the inhabitants have stopped building 

with wood; they use cement for the load-bearing parts of 

structures and use wood only in roof structures, window and 

door frames, or in ornamental situations where it could be easily 

replaced. Most of the structurally important wood used in 

Southeast Asia is either naturally durable or pressure treated. 

Joe Mauldin was asked for his assessment of the future of 

soil pesticides. Mauldin emphasized that the USDA laboratory 

in Gulfport, Mississippi, will continue to conduct research on 

alternatives to currently registered soil insecticides. In the near 

future, control of subterranean termites will mostly be accomplished with soil insecticides. Additional areas of subterranean 

termite control include biological control: fungi, bacteria and 

nematodes work well in the laboratory, but in the field these 

agents have not been shown to be effective. Termites apparently 

have a defense, or way to fend off these treatments, which 

renders them ineffective in the field. Dogs are also now being 

used in termite control. The dogs' ability to detect termites in a 

structure has not been tested, but those marketing these animals 

as termite detection "devices" claim the dogs are effective at 

locating termite infestations. 

Vemard Lewis inquired about closer scrutiny and a possible 

ban of fumigants in California. Apparently state regulatory 

officials are clamping down on use in structures and in wood 

yards. Ken Grace mentioned that there is a movement to register 

methyl bromide for fumigation in structures in Canada. NanYao Su reported that Dow Chemical Co. requested tests of 

sulfuryl fluoride to satisfy the U.S. Environmental Protection 

Agency. The goal of this research is to quantify the release of this 

fumigant from treated structures to support reregistration. 

John French, Joe Mauldin, Nan-Yao Su, and Ken Grace 

discussed the future of bait/toxicants for subterranean termite 

control. Nan-Yao reviewed the basic concept. Over the past 40 

years, the public has been relying on widespread use of huge 

quantities of pesticides in the soil to control subterranean termites. With bait toxicants, termites bring the toxicant back to 

colony and disperse it to colony mates, thereby causing the death 

of the entire colony. Until recently it has been difficult to 

determine whether termites simply move away or are killed by 

the bait. Nan-Yao feels it is crucial to monitor activity of 

foraging populations of field colonies by the mark-releaserecapture technique before we apply test toxins. Chemicals 

under examination currently are: (1) borates, (2) A-9248 (Abbott 

Laboratories), and (3) sulfluramid (Griffin Corp). A-9248 reduced a C. formosanus colony from 3.6 million to 75,000 

termites. Sulfluramid has toxicity, effective lethal time and 

acceptability to termites comparable to mirex. Sulfluramid is 

registered for use in baits for cockroaches and fire ants. Nan-Yao 

wants to emphasize that we are recommending use of bait 

toxicants to suppress termite populations in urban areas, not in 

forests. 

Michael Haverty discussed his work and that of Susan Jones 

and Nan-Yao Su on the disruption of caste structure and 

demography of colonies. Insect growth regulators induce molting of workers or pseudergates to superfluous soldiers and 

intercastes. The goal of this control strategy is to cause the 

termite population to crash because of an excess of dependent 

castes. This strategy works in the laboratory but, so far, has not 

been demonstrated in the field. Coptotermes can tolerate as 

much as 50 to 60 percent of the population in the soldier caste. 

Ken Grace has begun work to quantify Reticulitermes 

flavipes populations in southern Canada. He has determined that 

the colonies are as large as 3 million with extensive foraging 

territories. He will soon be moving to the University of Hawaii 

to study means of controlling the Formosan subterranean termite. He looks forward to a 12-month, warm field season! 

John French discussed his work in Australia with mirex in 

baits. Mirex bait-blocks kill a mound of Coptotermes lacteus in 

6 to 10 days. The system appears to be equally effective in 

buildings. He further emphasized that a bait/toxicant system 

must be foolproof to be used effectively by pest control technicians. The advantage of these systems is that they would use 

small amounts of pesticides, localized placements of pesticides, 

and the unused remnants can be withdrawn and disposed of after 

control has been achieved. It is sometimes necessary to practice 

"drastic carpentry" to place termite baits in the foraging path of 

the termites. Mirex-agar-sawdust baits kill Coptotermes 

acinaciformis in Sydney but not in Melbourne. There is obviously a behavioral or species difference. Another approach still 

used in Australia is to puff a toxic powder into termite galleries 

or wherever the termites aggregate. This strategy relies on the 

grooming behavior of termites to disperse the toxicant throughout the colony. The use of arsenic trioxide is still allowed in 

Australia. Inclusion compounds in peanut-shaped molecules 

64 USDA Forest Service Gen. Tech. Report PSW-128. 1991. 
can be used to dust termites. When ingested during grooming the in this area. We need to study this group extensively. Another 

chemical becomes active and kills the termites. ecologically important genus of termites is Nasutitermes. Our 

Finally, Michael Haverty made his pitch for chemotaxo- understanding of deforestation will be greatly enhanced by 

nomic research on termites. It was the consensus of the group knowledge of the wood-destroying (or wood-recycling) and 

that one of the areas of concern is the Pacific Rim. Coptotermes herbivorous termite species. 

species are probably the most economically important termites 

USDA Forest Service Gen. Tech. Report PSW-128. 1991. 65 

*U.S. GOVERNMENT PRINTING OFFICE: 1991-587-751/59263 
The Forest Service, U.S. Department of Agriculture, is responsible for Federal leadership in forestry. 

It carries out this role through four main activities: 

• Protection and management of resources on 191 million acres of National Forest System lands 

• Cooperation with State and local governments, forest industries, and private landowners to help 

protect and manage non-Federal forest and associated range and watershed lands 

• Participation with other agencies in human resource and community assistance programs to 

improve living conditions in rural areas 

• Research on all aspects of forestry, rangeland management, and forest resources utilization. 

The Pacific Southwest Research Station 

• Represents the research branch of the Forest Service in California, Hawaii, American Samoa and 

the western Pacific. 

Persons of any race, color, national origin, sex, age, religion, or 

with any handicapping conditions are welcome to use and enjoy 

all facilities, programs, and services of the U.S. Department of 

Agriculture. Discrimination in any form is strictly against agency 

policy, and should be reported to the Secretary of Agriculture, 

Washington, DC 20250.