FHTET-2004-12

BIOLOGY AND BIOLOGICAL CONTROL

OF PURPLE LOOSESTRIFE

Forest Health Technology

Enterprise Team

TECHNOLOGY

TRANSFER Biological

Control

LINDA M. WILSON, MARK SCHWARZLAENDER,

BERND BLOSSEY, AND CAROL BELL RANDALL

Forest

Service

U.S. Department

of Agriculture

Forest Health Technology Enterprise Team—Morgantown
The use of trade, firm, or corporation names in this publication is for information

only and does not constitute an endorsement by the U.S. Department of Agriculture.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and

activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs,

sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.)

Persons with disabilities who require alternative means for communication of program information

(Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at 202-720-2600

(voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W,

Whitten Building, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410 or call

202-720-5964 (voice and TDD). USDA is an equal opportunity provider and employer.

Federal Recycling Program

Printed on recycled paper

The Forest Health Technology Enterprise Team (FHTET) was created in 1995by the Deputy Chief for State and Private Forestry, USDA, Forest Service, to

develop and deliver technologies to protect and improve the health of American

forests. This book was published by FHTET as part of the technology transfer

series.

http://www.fs.fed.us/foresthealth/technology/

Cover photos: purple loosestrife—Eric Coombs; purple loosestrife beetle—S. Schooler;

purple loosestrife weevil—Mark Schwarzlaender.
Biology and Biological Control

of Purple Loosestrife

Linda M. Wilson1, Mark Schwarzlaender1,

Bernd Blossey2

, and Carol Bell Randall3

1

 Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, Idaho

2 Department of Natural Resources, Cornell University, Ithaca, New York

3 USDA Forest Service, Coeur d’Alene, Idaho

For additional copies of this publication, contact:

Carol Bell Randall

USDA Forest Service

Coeur d’Alene

Idaho

(208) 765-7343

crandall@fs.fed.us

Richard Reardon

FHTET, USDA Forest Service

Morgantown

West Virginia

(304) 285-1566

rreardon@fs.fed.us

In cooperation with Gary Piper (Washington State University)

and Eric Coombs (Oregon Department of Agriculture)

___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

iii

Contents

INTRODUCTION ..................................................................................................... 1

Overview ......................................................................................................................... 1

Biological Control of Weeds ............................................................................................. 2

About This Manual ........................................................................................................... 4

CHAPTER 1: GETTING TO KNOW PURPLE LOOSESTRIFE ................................................... 7

CHAPTER 2: BIOLOGY OF PURPLE LOOSESTRIFE BIOCONTROL AGENTS ............................13

Basic Insect Biology........................................................................................................ 13

Purple Loosestrife Biological Control Insects.................................................................... 14

Galerucella calmariensis L. ........................................................................................ 16

Galerucella pusilla Duftschmidt ................................................................................. 16

Hylobius transversovittatus Goeze ............................................................................. 19

Nanophyes marmoratus Goeze ................................................................................. 22

CHAPTER 3: DEVELOPING, IMPLEMENTING, AND MANAGING A PURPLE LOOSESTRIFE BIOLOGICAL CONTROL PROGRAM ..................................................................................27

1. Planning Your Purple Loosestrife Biocontrol Program.................................................. 27

2. Selecting Release Sites ............................................................................................... 28

3. Obtaining Purple Loosestrife Biocontrol Agents .......................................................... 30

3.1 Collecting purple loosestrife biocontrol agents ..................................................... 31

3.2 Rearing purple loosestrife biocontrol agents ......................................................... 35

3.3 Purchasing purple loosestrife biocontrol agents .................................................... 38

4. Handling and Releasing Purple Loosestrife Biocontrol Agents ...................................... 38

4.1 Handling purple loosestrife biocontrol agents....................................................... 38

4.2 Shipping purple loosestrife biocontrol agents ....................................................... 38

4.3 Releasing purple loosestrife biocontrol agents ...................................................... 40

Summary: Handling and Releasing Purple Loosestrife Biocontrol Agents..................... 41

5. Monitoring ................................................................................................................ 42

5.1 Monitoring Purple Loosestrife and its Biocontrol Agents........................................ 43

5.2 Detailed Purple Loosestrife Quantitative Monitoring ............................................. 45

6. Establishing a Photo Point for Monitoring.................................................................... 50
iv

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

SELECTED REFERENCES ..........................................................................................52

Purple Loosestrife Biology and Ecology ........................................................................... 52

Purple Loosestrife Biological Control ............................................................................... 54

Purple Loosestrife Biological Control Agents.................................................................... 55

Beetle Classification........................................................................................................ 56

General Biological Control ............................................................................................. 56

Other Control Methods................................................................................................... 57

Purple Loosestrife Internet Resources............................................................................... 57

GLOSSARY .........................................................................................................61

ACKNOWLEDGMENTS ............................................................................................64

SOURCES OF FIGURES ...........................................................................................65

APPENDIX: TROUBLESHOOTING GUIDE AND FORMS .....................................................67

Troubleshooting Guide: When Things Go Wrong................................................................. 69

Purple Loosestrife Biocontrol Release Form .......................................................................... 71

Monitoring Plan Questionnaire ............................................................................................ 72

Form 1: Purple Loosestrife Biocontrol Monitoring–Site Location ............................................ 73

Form 2: Purple Loosestrife Biocontrol Monitoring–Insect Monitoring ..................................... 74

Form 3: Purple Loosestrife Biocontrol Monitoring–Vegetation Monitoring .............................. 76

Form 4: Purple Loosestrife Biocontrol Monitoring–Associated Vegetation .............................. 78
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

v

Figure 1. Purple loosestrife. ............................................................................................................................... 1

Figure 2. Map of purple loosestrife distribution in the United States and Canada. ............................................. 1

Figure 3. Purple loosestrife: a) inflorescence; b) flowers; and c) seeds. .............................................................. 8

Figure 4. Purple loosestrife: a) seedling, b) one-year-old plant, and c) three-year-old plant. ............................... 9

Figure 5. Purple loosestrife sprouting from rootstocks amid previous year’s dead stems. .................................... 9

Figure 6. Diagram of beetle anatomy. ............................................................................................................. 13

Figure 7. Insect lifecycle showing complete metamorphosis. .......................................................................... 13

Figure 8. Galerucella adults: a) G. calmariensis and b) G. pusilla................................................................... 16

Figure 9. Adult Galerucella calmariensis feeding damage on purple loosestrife. ............................................. 16

Figure 10. Galerucella calmariensis egg clusters on purple loosestrife. ........................................................... 17

Figure 11. Galerucella calmariensis eggs and larvae on purple loosestrife. ..................................................... 17

Figure 12. Schematic lifecycle of Galerucella calmariensis and G. pusilla. .................................................... 17

Figure 13. Galerucella calmariensis larval “window-pane” feeding damage on purple loosestrife. .................. 18

Figure 14. Adult Hylobius transversovittatus. ................................................................................................... 19

Figure 15. Hylobius transversovittatus eggs in a purple loosestrife stem........................................................... 19

Figure 16. Hylobius transversovittatus larvae in a purple loosestrife: a) stem, and b) root. ............................... 20

Figure 17. Schematic lifecycle of Hylobius transversovittatus. ........................................................................ 20

Figure 18. Adult Nanophyes marmoratus on purple loosestrife flowers. ............................................................ 22

Figure 19. Nanophyes marmoratus egg in a purple loosestrife flower bud. ....................................................... 22

Figure 20. Nanophyes marmoratus larva in a purple loosestrife flower bud. ..................................................... 22

Figure 21. Nanophyes marmoratus adult exit hole in a dead purple loosestrife bud. ........................................ 23

Figure 22. Schematic lifecycle of Nanophyes marmoratus. ............................................................................. 23

Figure 23. Purple loosestrife biological control agents and the plant parts they attack..................................... 25

Figure 24. Purple loosestrife infestation. .......................................................................................................... 29

Figure 25. Non-waxed paper insect containers. ............................................................................................... 31

Figure 26. Collecting Galerucella calmariensis from purple loosestrife using the tap-and-funnel method. ....... 32

Figure 27. Sweep net for collecting purple loosestrife beetles. ........................................................................ 32

Figure 28. Aspirator used to collect purple loosestrife beetles.......................................................................... 33

Figure 29. Galerucella calmariensis collected in aspirators. ............................................................................ 33

Figure 30. Wading pools used to grow purple loosestrife and to rear Galerucella calmariensis. ....................... 36

Figure 31. Large mesh cages of potted purple loosestrife for rearing biocontrol agents. ................................... 37

Figure 32. Mesh-covered purple loosestrife plants in a greenhouse used to rear biocontrol agents. .................. 37

Figure 33. Shipping box for purple loosestrife beetles. ..................................................................................... 39

Figure 34. Releasing Nanophyes marmoratus on caged purple loosestrife........................................................ 41

Figure 35. Purple loosestrife infestation: a) before (1998) and b) after (2003) control by Galerucella beetles. .. 42

Figure 36. Purple loosestrife monitoring site. ................................................................................................... 44

Figure 37. Supplies needed to monitor purple loosestrife. ................................................................................ 47

Figure 38. Quadrat set within a purple loosestrife infestation. ......................................................................... 48

Figure 39. Estimating purple loosestrife coverage. ........................................................................................... 49

FIGURES

Table 1a. Species of Lythrum in the United States and Canada: native species. .............................................. 10

Table 1b. Species of Lythrum in the United States and Canada: introduced species......................................... 11

Table 2. Comparison of purple loosestrife and similar looking plants. .............................................................. 12

Table 3. Purple loosestrife biological control insects. ...................................................................................... 15

Table 4. Comparison of adult purple loosestrife biocontrol beetles and their damage. ..................................... 24

Table 5. Comparison of larvae and pupae of purple loosestrife biocontrol beetles and their damage. .............. 24

Table 6. Methods and timetable for collecting purple loosestrife biocontrol agents. ........................................ 34

Table 7. A rapid assessment scheme to monitor purple loosestrife and its biocontrol agents............................. 45

TABLES

___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

INTRODUCTION 1

Figure 1. Purple loosestrife. (UGA1291003)

Figure 2. Map of purple loosestrife distribution in the

United States and Canada.

INTRODUCTION

Overview

Purple loosestrife, Lythrum

salicaria (Figure 1), is a member of

the Loosestrife family (Lythraceae).

It is a large, perennial, wetland

plant that can grow up to 9 feet (3

m) tall. It was introduced to the

northeastern United States and

Canada in the 1800s from Europe,

probably as seed contained in soil

used as ship’s ballast. It was also

brought to North America for

ornamental and medicinal purposes.

Once established in North

America, this invasive weed quickly

spread in wetlands and waterways.

It is reported in nine Canadian

provinces and in the United States it

occurs in all states except Florida and

Hawaii (Figure 2). Although purple

loosestrife is declared noxious in 23

states and 5 Canadian provinces, it is

still sold as an ornamental plant in

some places.

In its native range, purple loosestrife

occurs from the United Kingdom

west to western Russia and from

Finland in the north to southern

Europe and northern Africa in the

south.
2 Introduction

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Purple loosestrife invades natural and disturbed wetlands, such as stream banks,

lakeshores, marshes, bogs, fens, sedge meadows, canals, drainage ditches, reservoirs,

riparian meadows, wet prairies, and sub-irrigated pastures. Established plants can

tolerate drier sites, posing a threat to agricultural lands and pastures.

Once established, purple loosestrife quickly crowds out most native vegetation, such

as sedges, rushes, cattails, and other wetland plant species. At high densities, purple

loosestrife can create near-monocultures. In addition to the loss of native

biodiversity, purple loosestrife harms waterfowl nesting habitat, has negative impacts

on some amphibians and algal communities, reduces water flow and quality, inhibits

transportation, and degrades hunting and fishing areas.

Successful management of purple loosestrife is an intensive process. Herbicides

approved for use around water provide short-term control of small infestations or

isolated plants, but may be impractical and uneconomical against large infestations.

Pulling small, individual plants is feasible; pulling large plants is very difficult. Plowing or disking small infestations is also possible, but will require repeated treatments

as plants will sprout from cut root pieces. Plowing large infestations is difficult and

generally ineffective. Mowing, burning, and flooding can be effective management

strategies, but are difficult, expensive, and time-consuming, and may have severe

negative, long-term consequences for wetland communities.

The biological control program for purple loosestrife began in 1985 at the International Institute of Biological Control in Switzerland with the search for, and testing

of, potential biological control agents. In 1992, two European leaf-feeding beetles

and a root-feeding weevil were imported and released. An additional flower-feeding

weevil was subsequently introduced in 1994, completing the complex of four insects

for biocontrol of purple loosestrife in the United States and Canada. Today, biological

control of purple loosestrife is one of the most widely implemented biocontrol of

weeds programs in North America.

Biological Control of Weeds

Most invasive weeds in the United States are not native: they arrived with immigrants

and commerce from Europe and, to a smaller extent, South Africa, Australia, and

Asia. Some plant species were brought intentionally for medicinal purposes or to

adorn gardens; others arrived as stowaways in ship’s ballast or clinging to livestock,

clothing, and other goods. Exotic plant species continue to be introduced accidentally

as contaminants of agricultural goods or purposefully through travel and commerce

(particularly for gardening), and some of these species will likely prove to be invasive

in the future. These immigrant plants are generally introduced without their natural

enemies, a complex of plant-eating organisms that are specialized to feed only on a

particular plant species. Lack of control by its natural enemies is one of the main

factors explaining why non-native plant species become major pests in the new area

of introduction.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

INTRODUCTION 3

Biological control of weeds is the deliberate use of naturally occurring organisms to

limit the distribution and abundance of a target weed. Classical biological control

uses host-specific, natural enemies from the plant’s native range (the terms “biological

control” or “biocontrol” used throughout this manual refer to classical biological

control). Natural enemies (also referred to as “biocontrol agents,” “bioagents,” and

“biological control organisms”) can directly kill or severely damage plants by destroying seeds, roots, foliage, or stems. Their damage may limit weed reproduction or

facilitate secondary infection from pathogens. These stresses reduce the weed’s

ability to compete with other plants. The aim of weed biocontrol, therefore, is to

restore at least a part of the ecological balance that limits the competitive ability of an

invasive plant species in its native range.

There are a number of advantages to classical biological control of weeds. Biocontrol

is selective of a specific weed or closely related group of weeds; it can provide longterm control; and the biocontrol agents are self-perpetuating, thus avoiding recurring

acquisition, rearing, and reintroduction costs. The disadvantages of biocontrol of

weeds are the high initial costs of a program and the uncertainty that the agents will

be effective. Additional disadvantages include the risk of unintended, adverse impacts

on other plant species (non-target effects) and that, once released, biological control

agents cannot be retrieved. Because biocontrol agents are irretrievably introduced

into the environment, they must be carefully selected and extensively studied before

being approved for release.

Natural enemies used in classical biological control of weeds include insects and

mites, and sometimes nematodes and fungi. Beetles, flies, and moths are among the

most commonly used insects. To be considered for release in the United States, insect

biological control agents must eat and develop only on the target plant, and in some

cases, on only a few closely related plant species. Also, the insect’s lifecycle should be

closely matched, or synchronized, with the target plant’s. For example, when properly synchronized, foliage-feeding insects would be in the feeding stage when the

weeds are actively growing, and root-feeding insects would be in the feeding stage

when resources in below-ground tissues are at their maximum.

The most important precondition for an insect to be used as a biocontrol agent is that

it will die without the target plant. This is known as host specificity, and is the ecological cornerstone of classical biological control of weeds. Potential biocontrol

agents often undergo more than five years of rigorous testing to ensure that hostspecificity requirements are met. These studies are important in order to:

· Have effective, safe biocontrol agents

· Introduce biocontrol agents that damage only the target plant

· Protect non-target plant species

The United States Department of Agriculture–Animal and Plant Health Inspection

Service–Plant Protection and Quarantine (USDA-APHIS-PPQ) is the federal government agency responsible for authorizing the importation of biocontrol agents into
4 Introduction

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

quarantine. All states have their own final approval process to permit field release of

plant biocontrol agents. The Technical Advisory Group (TAG), an expert committee

of volunteers representing federal land management and environmental protection

agencies, reviews all petitions to import new biocontrol agents, and makes recommendations to USDA-APHIS to aid their decision making process. Effective laws and

regulations are in place to minimize the risks to native plant and animal communities

associated with the introduction of exotic organisms to manage weeds. Weed

biocontrol researchers work closely with USDA-APHIS-PPQ and TAG to further

maximize the environmental safety of weed biocontrol programs.

Although weed biocontrol is an effective and important ecological management tool,

it does not work in all cases and is not expected to completely eradicate a weed. For

example, the expectation of classical biological control of purple loosestrife is to

reduce the abundance of purple loosestrife to levels that do not damage the rest of the

plant community. In general, classical biocontrol programs reduce a weed’s ability to

compete with native plants. Often, biological control can be integrated with other

methods of weed control—e.g., chemical or cultural control and livestock grazing.

For more information on classical biological control of weeds we recommend reading

the literature listed in the Selected References section of this manual.

About This Manual

This manual provides background information on purple loosestrife biology and on

each of the four insects selected for biocontrol of purple loosestrife. It also provides

guidelines to establish and manage a purple loosestrife biocontrol program. The

manual is divided into the following chapters:

Chapter 1 provides a detailed description of purple loosestrife, including scientific

name, description of the leaves, stems, flowers, seeds, habitat, and occurrence in

the United States and Canada. Photographs, and drawings are provided.

Closely related Lythrum species, as well as unrelated plant species often confused with purple loosestrife are also described.

Chapter 2 describes the four purple loosestrife biocontrol agents: two leaf beetles

and two weevils. Included is information on biocontrol agent identification,

lifecycles, and biology. This chapter is particularly useful for identifying

biocontrol agents in the field.

Chapter 3 includes detailed information and guidelines on how to plan, implement,

monitor, and evaluate an effective purple loosestrife biocontrol program incorporating one or more of the four biocontrol agents. Included are guidelines and

methods for:

• Planning a purple loosestrife biocontrol program

• Selecting and preparing release sites
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

INTRODUCTION 5

• Collecting, handling, transporting, shipping, and releasing purple loosestrife

biocontrol agents

• Monitoring of biocontrol agents and their effects on vegetation

Glossary defines technical terms essential to communicating specifics of purple

loosestrife biological control.

Selected References are provided from the large body of literature on purple

loosestrife biology, ecology, and biological control. Also included is a comprehensive list of Internet web sites that provide a wealth of practical information.

Appendix provides a troubleshooting guide, examples of insect release and monitoring forms, and vegetation monitoring forms. (These forms may be reproduced for use as needed.) These are, in order of appearance:

Troubleshooting Guide: When Things Go Wrong

Purple loosestrife Biocontrol Release Form

Monitoring Plan Questionnaire

Form 1: Purple Loosestrife Biocontrol Monitoring – Site Location

Form 2: Purple Loosestrife Biocontrol Monitoring – Biocontrol Agents

Form 3: Purple Loosestrife Biocontrol Monitoring – Vegetation

Form 4: Purple Loosestrife Biocontrol Monitoring – Associated Vegetation

___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 1: Getting to Know Purple Loosestrife 7

CHAPTER 1: GETTING TO KNOW PURPLE LOOSESTRIFE

Scientific name: Lythrum salicaria L.

Common names: Purple loosestrife, purple lythrum, spiked loosestrife

Family Lythraceae (Loosestrife)

Description: Purple loosestrife (Figure 3a) is an erect, herbaceous, perennial

wetland weed that is commonly found along waterways and other wetland

habitats. It was introduced from Europe during the late 1800s.

Leaves: Purple loosestrife leaves are 2-5 inches (5-12 cm) long and narrow with a

rounded or heart-shaped base, and smooth-edged. The stalkless leaves are

arranged opposite or alternate along the stem, and lower leaves often form a

whorl around the stem.

Stems: One of the more recognizable features of purple loosestrife is its squareshaped stems. They are five- or six-sided (you can feel the edges of the stem

when you roll it between your fingers), woody, and can be either smooth or

covered with downy hairs. Stems have short, slender branches and evenly

spaced nodes. Mature plants have up to 30 flowering stems, which can reach a

height of 5-9 feet (1.5 to 3 m). Dead stems persist through the winter and often

decay slowly over several years, and new shoots are produced each spring from

buds on the persistent, woody rootstock.

Flowers: The inflorescence of purple loosestrife is a spike of numerous, showy,

reddish-purple or magenta flowers set in clusters (Figure 3b). Each flower

measures about 0.6-0.8 inches (15-20 mm) across, has five to seven petals, and a

small, yellow center. Flowering occurs from mid-June to September, depending

on location.

Seeds: Seeds are produced in rounded capsules about 0.24 inches (6 mm) in length.

The capsules open to release more than a hundred tiny, light brown seeds about

the size of poppy seeds (Figure 3c). Water, wind, wildlife, and humans easily

spread the lightweight seeds that are shed throughout the winter. Purple loosestrife is a prolific seed producer; a single mature plant can produce several

million seeds. When purple loosestrife densities are high, billions of seeds are

produced per acre. Seed viability is greater than 90 percent and seeds can

remain viable in the soil for many years.
8 Chapter 1: Getting to Know Purple Loosestrife

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 3. Purple loosestrife: a) inflorescence (UGA1291004); b) flowers

(UGA1291005); and c) seeds (UGA1291006).

Biology and Ecology: Seeds germinate in late spring and early summer in open,

sunny places when soil temperatures reach 68°F (20°C). Seedlings lodge into

moist soil and quickly grow to over 3 feet (1 m) tall in their first growing season, and many even flower (Figure 4). Even young plants develop a large

taproot, and have an extensive rootstock by the end of the first growing season.

The mature size of the plant will depend, in part, on growing conditions, soil

type, water level, the genetic potential of the plant, and plant density. After the

first extreme frosts in fall, all above-ground plant parts will die back. Plants

resprout each spring from their large rootstocks (Figure 5).
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 1: Getting to Know Purple Loosestrife 9

Any sunny or partially shaded wetland is susceptible to purple loosestrife invasion. Although purple

loosestrife generally prefers moist soils, mature purple loosestrife plants can tolerate a wide range of

water levels, pH and climatic conditions, soil,

and vegetation types. In flooded areas, the plant

forms dense, fibrous rootmats.

Purple loosestrife spreads primarily by seeds.

Seeds are dispersed by floating on streams, by

birds, wildlife and livestock, or in the mud of

vehicle tires or boots. In addition to spread by

seeds, purple loosestrife also spreads vegetatively. Root fragments cut from the plant can

produce new plants and stem pieces may generate new infestations when they float downstream

and lodge against a streambank.

Comments: Although still sold and planted for

its beauty as an ornamental, purple loosestrife’s

habit of devastating waterways and wetlands has

caused its sale to become restricted or, in some

states, illegal. It is especially important to know

that the species called European wand loosestrife, L. virgatum, and widely sold as an ornamental, is the same species as purple loosestrife

(L. salicaria). Thus, garden and pond plants that

are being sold as L. virgatum are in fact L.

salicaria, and may be illegal for sale in your area.

Studies have shown that other ‘varieties’ of

loosestrife sold as ornamentals are generally not

sterile as advertised.

In addition to purple loosestrife, there are a

number of other Lythrum species in the United

States and Canada. Some species are native (see

Table 1a) and some, like purple loosestrife, are

introduced (see Table 1b).

Other plant species are often confused with

purple loosestrife. While they are not related to purple loosestrife, they may be similar in appearance. They include hardhack (Spirea douglasii), fireweed (Epilobium angustifolium), and blue

vervain (Verbena hastata) (see Table 2).

Figure 4. Purple loosestrife: a) seedling, b) one-yearold plant, and c) three-year-old plant.

Adapted from Thompson et al. (1987).

Figure 5. Purple loosestrife sprouting from rootstocks amid

previous year’s dead stems. (UGA1291009)
10 Chapter 1: Getting to Know Purple Loosestrife

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Wing-angled loosestrife

(Lythrum alatum)

Saltmarsh loosestrife

(L. lineare)

Florida loosestrife

(L. flagellare)

California loosestrife

(L. californicum)

Curtiss' loosestrife

(L. curtissii)

Low loosestrife

(L. ovalifolium)

Table 1a. Species of Lythrum in the United States and Canada: native species.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 1: Getting to Know Purple Loosestrife 11

Table 1b. Species of Lythrum in the United States and Canada: introduced

species. Not shown: spatula-leaf loosestrife (L. portula) and

thyme-leaf loosestrife (L. thymifolia).

European wand loosestrife

(Lythrum virgatum (= L. salicaria)

Hyssop loosestrife

(L. hyssopifolia)

Punkamole

(L. maritimum)

Three-bract loosestrife

(L. tribracteatum)
12 Chapter 1: Getting to Know Purple Loosestrife

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Hardhack (Spirea douglasii)

Family: Rosaceae

Description: Stems are round; leaves

are alternate, oval to oblong, on short

petioles, with toothed margins from the

midpoint to the tip, and whitish on the

lower surface; 5-petaled, rose-pink

flowers occur in a dense panicle, 5-15

cm long.

Fireweed (Epilobium angustifolium)

Family: Onagraceae

Description: Stems are round; leaves

are alternate, smooth, and lanceshaped, very short petiole; purple

flowers borne in a loose, terminal

raceme or in the axils of uppermost

leaves.

Blue vervain (Verbena hastata)

Family: Verbenaceae

Description: Stems are square; leaves

are opposite, rough-hairy, narrowly

oblong on short petioles, toothed or

dissected; purple-blue flowers arise on

slender, dense spikes—terminal

flowers open first.

Purple Loosestrife (Lythrum salicaria)

Family: Lythraceae

Description: Stems are square-sided

(more than 4 sides); leaves are

opposite or alternate, entire with a

rounded, clasping (no petiole) base;

flowers have 5-7 reddish-purple or

magenta petals and a yellow center

arranged in a loose spike.

Table 2. Comparison of purple loosestrife and similar looking plants. (Left to right, top to bottom: UGA1291040,

UGA1291041, UGA1291042, UGA1291043)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 13

Figure 6. Diagram of beetle anatomy (a

ladybird beetle is used as the

example).

Head

Thorax

Abdomen

Figure 7. Insect lifecycle showing complete

metamorphosis (a weevil is used as

the example).

CHAPTER 2: BIOLOGY OF PURPLE LOOSESTRIFE BIOCONTROL AGENTS

Basic Insect Biology

Insects are a very large, diverse class of animals. Basic knowledge of insect anatomy

and lifecycle will help in understanding insects, and recognizing them in the field.

Adult insects have several unique characteristics; an exoskeleton (outside skeleton), a

segmented body comprised of a head, thorax,

and abdomen, and three pairs of legs (Figure

6). Because insects have a skeleton on the

outside, they must shed their skeleton as

larvae in order to grow. This process of

shedding the exoskeleton is called molting.

The period between molts is called an

instar. As larvae, insects grow a lot,

often having to go through three to

five molts.

Mature larvae molt into a pupa, the

stage when the insect body changes

from a larva into the adult. Insect

development from an egg to adult is

called metamorphosis. The insects we

will be discussing in this manual go

through complete metamorphosis,

meaning they have four developmental stages: egg, larva, pupa, and adult

(Figure 7). Once the insects become

adults, they stop growing, and therefore stop molting.
14 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Purple Loosestrife Biological Control Insects

All four of the insect species introduced for purple loosestrife biocontrol are beetles.

Beetles are hard-bodied insects with tough exoskeletons. Adult beetles possess two

pairs of wings: the front pair is thickened to form a hard covering, called the elytra,

which meet in a straight line down the middle of the back and cover the larger, membranous hind wings, which are used for flight. Beetles that feed on plants, like those

used for purple loosestrife biocontrol, have chewing mouth parts.

The four species used for purple loosestrife biocontrol belong to three different

families of beetles: one family of leaf beetles (two species) and two families of weevils

(one species each). Leaf beetles are small, foliage-feeding beetles; both adult leaf

beetles and their larvae feed externally on plant foliage. Larval feeding often is more

damaging, and can result in complete defoliation of plants. Weevils are generally

plant-feeding beetles with long snouts bearing chewing mouthparts at the tip. They

use the snout to chew and feed inside plant tissues or to notch out holes in which to

lay their eggs. Similar to leaf beetles, weevil larvae (which feed internally in the

stems, roots or flowers) often cause more damage to plants than adults. However,

some weevil adults do cause significant feeding damage to foliage.

The leaf beetles are Galerucella calmariensis L. and Galerucella pusilla Duftschmidt;

one weevil is a root-mining weevil, Hylobius transversovittatus Goeze and the other

is a flower-feeding weevil, Nanophyes marmoratus Goeze (Table 3). Each species is

described in the following sections.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 15

Insect Type Scientific Name

Common Name Appearance

Leaf beetle Galerucella calmariensis (L.)

Black-margined loosestrife beetle

Galerucella pusilla Duftschmidt

Golden loosestrife beetle

Actual length

Weevil Hylobius transversovittatus Goeze

Loosestrife root weevil

Actual length

Weevil Nanophyes marmoratus Goeze

Loosestrife flower weevil

Actual length

Table 3. Purple loosestrife biological control insects. (Top and center: UGA1291044 and UGA1291045)
16 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 9. Adult Galerucella calmariensis

feeding damage on purple

loosestrife (UGA1291009).

Galerucella calmariensis L.

Common name: Black-margined loosestrife beetle

Galerucella pusilla Duftschmidt

Common name: Golden loosestrife beetle

Order: Coleoptera

Family: Chrysomelidae

Galerucella calmariensis and G. pusilla are two nearly

identical species of leaf-feeding beetles (Figure 8). Both

beetles are light brown in color, but G. calmariensis

(Figure 8a) usually has a black triangle or black line on the

thorax while in G. pusilla (Figure 8b), the line is thin or

nearly absent (these characters develop fully only in

overwintered beetles). The beetles are the same size—

about 0.15 to 0.3 inches (4 -6 mm) in length—and have

the same habits. Released in 1992, these two leaf beetles

were the second loosestrife insects to be introduced in the

United States and Canada for biological control of purple

loosestrife. They are now widely established in more than

30 states and 8 provinces where purple loosestrife is a

problem.

In early spring, adult beetles emerge from their overwintering sites in plant litter. They live eight to ten weeks

after they emerge in the spring, feeding at first, and then

mating and laying eggs. Adult feeding on loosestrife

leaves and young shoot tips results in a characteristic

“shothole” damage of the plants (Figure 9). Mating and

oviposition begin in late May or early June. A single

female can lay as many as 400 eggs in her lifetime. Eggs

are laid in batches of one to ten on leaves and stems (Figure 10). Each egg is covered

with a black line of frass (fecal deposit).

Larvae hatch from eggs after about one

week and move to leaf buds where they

remain well-concealed as they feed. As

they get older and larger, larvae openly feed

on leaves and stems. The larvae of the

loosestrife beetles look like tiny caterpillars

with black heads and yellowish bodies

(Figure 11). After completing three instars,

mature larvae move into the litter beneath

purple loosestrife plants to pupate. On

flooded purple loosestrife they pupate in the

spongy tissue (called aerenchyma) that

develops on the flooded portion of the stem.

Figure 8. Galerucella adults:

a) G. calmariensis

(UGA1291008) and

b) G. pusilla.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 17

Figure 11. Galerucella calmariensis

eggs and larvae on purple

loosestrife. (UGA12910012)

Figure 10. Galerucella calmariensis

egg clusters on purple

loosestrife. (Background:

UGA12910010; inset:

UGA1291011)

Figure 12. Schematic lifecycle of Galerucella calmariensis and G. pusilla. Solid colored bars

represent the length of activity for each of the life stages. Short patterned bars for the

upper three stages represent potential second generation activity, while the long patterned

bars at the bottom represent adult overwintering.

Egg

Larva

Pupa

Adult

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

123456 123456

123456

123456

123456

123456

123456 123456

123456

123456

123456

123456

123456 123456

123456

123456

123456

123456

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567 12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

Development time, from egg to adult, is 30-40 days (Figure 12). New adults emerge

between mid-June and mid-July, feed for a limited time to accumulate body fat, and

then seek overwintering sites in the leaf litter.

Both loosestrife beetle species usually have only one generation each year, but a

partial second generation may occur in warm regions where the first new generation

adults emerge before mid-June (before the summer solstice). At this time of year,

warm temperatures and long day lengths may trigger beetles to mate and produce a

second generation. If a second generation develops, new adults may emerge as late as

the end of August.
18 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 13. Galerucella calmariensis larval

“window-pane” feeding damage on

purple loosestrife. (Left to right:

UGA1291013, UGA1291014, UGA1291015)

Impact:

Adult loosestrife beetles are very good fliers and they can easily find new patches of

purple loosestrife on which to feed and reproduce. Loosestrife beetle adults are

known to disperse 2-4 miles a year. Although loosestrife beetles survive under a

range of conditions, they do not thrive in shade or in areas where water levels fluctuate dramatically (e.g., dam reservoirs).

Larvae feed on the underside of leaves, stripping the photosynthetic tissue off while

leaving the upper leaf cuticle and epidermis intact, creating a “window-pane” effect

(see Figure 13). At lower larval densities, plants are less severely damaged. At high

densities (greater than 4-5 larvae/inch stem or 2-3 larvae/cm of shoot length), stems

can be defoliated. Large loosestrife beetle

populations can defoliate 100 percent of the

plants in an infestation many acres/hectares in

size. While plants may recover after defoliation

and flower late in the year, in some areas loosestrife beetle feeding has completely

suppressed flowering. Plants that regrow after defoliation are often shorter and

bushier than normal, unattacked plants.

Predators and parasites of loosestrife beetles have also been reported in North

America, although the specialist wasps that attack these species in Europe were

carefully excluded when beetles were imported. Adult loosestrife beetles can be

parasitized by a nematode that feeds and develops inside the beetle, eventually killing

it. Other native predators of loosestrife beetles are ladybeetles, true bugs, predaceous

beetles, spiders, and possibly birds, frogs, and lizards.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 19

Hylobius transversovittatus Goeze

Common name: Loosestrife root weevil

Order: Coleoptera

Family: Curculionidae

Hylobius transversovittatus is a large, reddish-brown weevil, 0.4 to 0.6 inches (10 to

14 mm) in length (Figure 14). First released in 1992, it was the first of the loosestrife

biocontrol insects to be introduced. It is now established at many sites across the

United States and Canada. This weevil is nocturnal and long-lived as an adult (two to

three years or longer).

In spring, overwintering adult weevils

appear shortly after purple loosestrife

shoots sprout. Loosestrife root weevils

are most active at night, but can be found

on their host plants in the early evening

and morning hours or during cool, overcast, or rainy days. During warm, sunny

days, they hide in the litter, often at the

base of the plants.

Adults begin feeding on foliage and young

stems, and within two weeks, mating and oviposition begin, which can last until

September. Females deposit single, white, oval-shaped eggs into the soil close to the

root-crown or into purple loosestrife stems (Figure 15). A female can produce more

than 100 eggs annually.

Young larvae hatch in about eleven days

and start to mine the root hairs (if hatched

from eggs laid in the soil) or into the stem.

They later feed on the outside of the root,

and then mine into the center of the root

where they continue to feed for one to two

years (Figure 16). Mature third instar

larvae move to the upper part of the root to

pupate.

The new loosestrife root weevil generation

emerges from late June to October. Development time from egg to adult is one to two

years (see Figure 17).

Figure 15. Hylobius transversovittatus eggs

in a purple loosestrife stem.

(UGA1291016)

Figure 14. Adult Hylobius transversovittatus.

(UGA0002033)
20 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 17. Schematic lifecycle of Hylobius transversovittatus. Solid colored bars represent the length

of activity for each of the life stages, with adult overwintering presented by the patterned

bars. A single generation can take one to two years to mature.

Egg

Larva

Pupa

Adult

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

123456789012345678901234567890121234567890123456789012345678901212345678901234567890123456789012123456789012345678 123456789012345678901234567890121234567890123456789012345678901212345678901234567890123456789012123456789012345678

123456789012345678901234567890121234567890123456789012345678901212345678901234567890123456789012123456789012345678

1 8

123456789012345678901234567890121234567890123456789012345678901212345678901234567890123456789012123456789012345678

123456789012345678901234567890121234567890123456789012345678901212345678901234567890123456789012123456789012345678

a b

Figure 16. Hylobius transversovittatus larvae in a purple loosestrife: a) stem, and b) root.

(Left to right: UGA1291017 and UGA129018)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 21

Impact:

The rate of attack (number of larvae feeding in a root) and damage to the plant varies

depending on the size and age of the rootstock, the density of purple loosestrife

plants, and the number of weevils at the site. Usually, only one or two larvae feed in

the same root, but as many as 20 larvae have been found in a single, large root.

Root feeding by loosestrife root weevil larvae can be very destructive to the roots,

especially at high larval densities. Small rootstocks can be severely damaged or killed.

Large roots can withstand substantial feeding pressure over several years before

significant damage becomes noticeable. However, attacked plants are shorter, have

reduced root and shoot biomass, and produce fewer seeds.

The loosestrife root weevil is tolerant of a wide range of environmental conditions.

However, where water levels fluctuate, females may not be able to lay eggs at the

base of the plant. Larvae may drown in roots that are submersed in water for a

prolonged period of time (several months). For these reasons, the loosestrife root

weevil should not be released in permanently flooded sites.

The loosestrife root weevil can be used effectively with the loosestrife leaf beetles.

The combined effects of the three biocontrol agents is expected to be greater than the

effects of either insect alone. For example, purple loosestrife regrowth following

defoliation by Galerucella leaf beetles is greatly reduced when plants are also attacked

by the root feeder.

Comments:

A semi-artificial diet has been developed to facilitate mass rearing of the loosestrife

root weevil. Refer to the rearing purple loosestrife biocontrol agents section in

Chapter 3 of this manual for more information about the semi-artificial diet.
22 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 19. Nanophyes

marmoratus egg

in a purple

loosestrife flower

bud. (UGA1291019)

Figure 20. Nanophyes

marmoratus larva

in a purple

loosestrife flower

bud. (UGA1291020)

Nanophyes marmoratus Goeze

Order: Coleoptera

Family: Brentidae (see Note below)

Common name: Loosestrife flower weevil

Nanophyes marmoratus is a minute, dark brown weevil, measuring 0.06-0.08 inches

(1.4-2.1 mm) in length (Figure 18). It was introduced from Germany and first released in New York and Minnesota in 1994.

Adult loosestrife flower weevils overwinter in the leaf

litter, and emerge from sites in late May to early June

to feed on young purple loosestrife leaves. As soon as

flower buds develop, weevils move to the flower

spikes, where they feed on the buds, mate, and begin

to lay eggs. Females continue to lay eggs throughout

the peak flowering period of purple loosestrife.

Eggs are laid singly into the tips of flower buds before

petals are fully developed (Figure 19). Larvae feed on

developing ovaries, hollowing out the bud in the

process. As a result, attacked buds never flower. All

attacked buds senesce and most drop off the inflorescence before new adult weevils emerge. Mature larvae

1use frass to form pupation chambers at the bottom of the bud (Figure 20).

The new generation loosestrife flower weevils

emerge from dried, hollowed-out buds in July and

August and feed on the

remaining green leaves of

purple loosestrife before

seeking overwintering sites

in leaf litter. Holes chewed

in the buds when the

loosestrife flower weevils

emerge from their pupation

chambers provide evidence

that the weevil is present at

the site (Figure 21) Most

damaged buds drop from the plant. The loosestrife

flower weevil has one generation per year. Complete

development from egg to adult takes about one month

(Figure 22).

Figure 18. Adult Nanophyes

marmoratus on purple

loosestrife flowers.

(UGA0021100)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 23

Figure 21. Nanophyes marmoratus

adult exit hole in a

dead purple loosestrife

bud. (UGA1291021)

Figure 22. Schematic lifecycle of Nanophyes marmoratus. Solid colored bars represent the length of

activity for each of the life stages, with adult overwintering represented in the patterned

bars. This weevil produces one generation per year.

Egg

Larva

Pupa

Adult

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567 12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212345678901234567

Impact:

Bud feeding by adults causes premature flower bud

drop; attack by larvae kills the bud, thus preventing

flowering and seed production. At high loosestrife

flower weevil densities, larval feeding can reduce

seed output of a purple loosestrife plant by about

60 percent.

The effectiveness of the loosestrife flower weevil

may be reduced where it occurs with the loosestrife

beetle (Galerucella). This is because high levels of

defoliation by the loosestrife beetle prevents purple

loosestrife from flowering, and consequently limits

activity of the flower weevil. Initially, the loosestrife flower weevil should only be

released where the beetles do not occur or where their densities are low.

Note: The taxonomic placement of the genus Nanophyes is in transition, and thus

you may find it listed under three different family names. The genus was historically

in the weevil family Curculionidae, and was reclassified in 1995 into the weevil family

Brentidae. It was later moved to the family Apionidae (1999). However, the latest

classification (2002) returns Nanophyes and all species formerly in the family

Apionidae to the family Brentidae. For the purpose of this manual, this classification

system is followed. All three families are commonly known as weevils. For more

information, key references are provided in the Selected Reference section.

Another species, N. brevis, was tested and approved for importation but was never

released in North America because of problems with parasitism.
24 Chapter 2: Biology of Purple Loosestrife Biocontrol Agents

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Table 5. Comparison of larvae and pupae of purple loosestrife biocontrol beetles and their damage.

Species Larval Description and

Feeding Characteristics Effects

Galerucella calmariensis

and G. pusilla

Larva is yellow with brown cross

markings and a dark brown head

capsule; larva feeds on foliage,

window-paning the leaves (top layer of

leaf cuticle and epidermis is intact);

pupates in soil or aerenchyma (on

flooded plants).

Reduces shoot height, root mass,

generally stresses plant.

Hylobius transversovittatus

Larva is C-shaped, white with light

brown head capsule; larva feeds and

pupates inside root.

Reduces shoot height, root mass, root

storage reserves, and generally stresses

plant.

Nanophyes marmoratus

Larva is C-shaped, white with light

brown head capsule; feeds in bud on

developing ovary, killing bud; pupates

inside hollowed bud.

Reduces flowering and seed

production.

Table 4. Comparison of adult purple loosestrife biocontrol beetles and their damage.

Scientific Name Galerucella calmariensis

and G. pusilla

Hylobius transversovittatus Nanophyes marmoratus

Common Name Loosestrife beetle Loosestrife root weevil Loosestrife flower weevil

Adult Description

Light brown leaf beetles Large reddish-brown weevil

with white spots, large snout

Small, shiny, dark brown

weevil

Life Cycle

One generation per year,

may have a partial second

generation

Long lived, often more than

two years.

One generation per year

Body Shape/Size

Cylindrical body shape,

0.15 to 0.3 inches (4 -6 mm)

in length

Ovoid body shape, 0.4 to

0.6 inches (10 to 14 mm) in

length

Round-ovoid body shape,

0.06-0.08 inches (1.4 to 2.1

mm) in length

Eggs

Lays eggs in clusters on

leaves and stems, covered

with fecal strands

Lays eggs (one or more) in

soil or stem near base

Lays eggs singly inside

flower bud

Damage

Adults feed on foliage

causing a 'shothole' damage

pattern in the leaves

Adults feed on edge of

leaves

Adults feed on young leaves

and flower buds

Summary:

Four species of beetles are established in the United States and Canada for the biological control of purple loosestrife. For a quick reference to the beetles, Table 4

compares the adult beetles and their damage, and Table 5 compares the larvae and

pupae, and their damage. Figure 23 is an illustration of a purple loosestrife plant

showing which parts of the plant are attacked by each of the biocontrol beetles.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 2: Biology of Purple Loosestrife Biocontrol Agents 25

Figure 23. Purple loosestrife biological control agents and the plant parts they attack (drawing adapted from

Thompson et al. 1987): a) Nanophyes flower weevil adult (UGA0002035); b) and c) Galerucella leaf

beetle adult (UGA1291023) and larva (UGA0022078); d) Hylobius root weevil adult on leaf (UGA0021099),

and e) emerging from root (UGA0002034).

___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 27

CHAPTER 3: DEVELOPING, IMPLEMENTING, AND MANAGING A PURPLE

LOOSESTRIFE BIOLOGICAL CONTROL PROGRAM

Implementing a purple loosestrife biocontrol program involves planning the program,

selecting release sites, obtaining and releasing insects, and monitoring the success of

the program. Monitoring determines (1) if the insects successfully establish at a site,

(2) if their populations increase over time, (3) how attack and damage impact the

purple loosestrife populations over time, and (4) how other plants in the wetland

community respond to release of biological control agents. Depending on the size of

your program, monitoring activities may vary among release sites. However, evaluating the success of a purple loosestrife biological control program requires a long-term

commitment to regular observations and assessments. Guidelines and protocols to

plan, develop, implement, and monitor a purple loosestrife biocontrol program are

outlined in this chapter.

This chapter includes six sections:

1. Planning your purple loosestrife biocontrol program

2. Selecting release sites

3. Obtaining purple loosestrife biocontrol agents

4. Handling and releasing purple loosestrife biocontrol agents

5. Monitoring purple loosestrife, the biocontrol agents, and other vegetation

6. Establishing a photo point for monitoring

Familiarity with all aspects of the program before beginning will greatly facilitate its

implementation and increase its chances of success.

1. Planning Your Purple Loosestrife Biocontrol Program

Before you begin implementation, careful planning of your purple loosestrife

biocontrol program is important. Setting biocontrol program goals, and understanding what is involved in implementing and managing a purple loosestrife biocontrol

program increases the probability for success of your program. All of the following

are important components of pre-program planning:
28 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

a) Assess the current status of purple loosestrife in your management area

and adjacent ownerships.

• Determine how much purple loosestrife occurs in your area and develop

a distribution map.

• Determine what other management strategies have been employed

against purple loosestrife in your area. Determine if biocontrol is an

appropriate strategy.

• Discuss your program plans with neighboring landowners/managers, or

coordinated weed management areas (CWMAs).

• Consult with your agency or university biocontrol expert, cooperative

weed management area, or county weed superintendent to become

familiar with other purple loosestrife activities in your area, especially

spraying or mowing programs that may affect a biocontrol program.

b) Define the goals of your program.

• Determine the weed management objective for your area. If you want

to eradicate purple loosestrife from your area, then biocontrol is not the

most effective management technique to accomplish this. However, if

you simply want to reduce loosestrife cover, flowering, and seed production, and to promote the growth of native plants, then a biocontrol

program may be compatible with your management objectives.

• Determine precisely how you will measure control based on your stated

goals.

• Outline a long-term management strategy.

• Determine the projected lifespan of the project.

c) Decide which biocontrol agent(s) to release.

d) Establish support logistics.

• Commit resources for field equipment and supplies (if needed).

• Recruit and train personnel.

• Identify sources of biocontrol agents.

• Outline yearly activities.

2. Selecting Release Sites

The sites that you select to release biocontrol insects should be carefully chosen to

meet the primary goal(s) of your program. Consider the following when selecting

your site:

• Sites selected to function as future collecting and redistribution sites (field

insectaries) should be sufficiently large—ideally greater than 10 acres

(4 ha)— safe from disturbance or vandalism, and should be accessible for

regular monitoring and collection activities. Also, assess these sites for use

as demonstration areas for educational and training purposes.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 29

Figure 24. Purple loosestrife infestation. (UGA1291024)

• Sites intended for long-term insect and vegetation monitoring of control

success should be safe from interference by other weed management programs and safe from vandalism. You need a long-term commitment by the

landowner to allow your monitoring to proceed for a decade or longer.

Consider restricting collection of beetles from these sites in order to track

the growth of insect populations.

Visit several prospective release sites. Use the following guidelines and criteria to

select a site:

Site factors: An infestation covering a minimum of 1 acre (0.4 ha) in size is

recommended, but a larger infestation, such as that shown in Figure 24, is

better. Choose a site that is in full sunlight (Galerucella beetles, particularly,

prefer full sun). Ideally, select a site that has a moisture gradient: this will allow

the beetles to select their preferred moisture levels, and large water fluctuations

will not jeopardize the release program. Avoid sites that are highly disturbed,

where other weed control methods (mowing/cutting, burning) are planned, or

where pesticides are used frequently.

Presence of biocontrol agents: Make sure you are aware of and coordinate with

other biocontrol activities in your area. If other biocontrol agents are already

present at the selected site, move on and choose a different location for release.

For example, if you want to establish Nanophyes in a field insectary site, first be

sure that Galerucella is not present.

Ownership: The landowner must be willing to permit release and monitoring over

several years. When getting permission to use a site, be sure to secure the

following: 1) written permission from the landowner or land manager allowing

use of the area as a release site, 2) written agreement by the landowner allowing

access to the site for monitoring and collection for a period of at least 10 years,

and 3) permission to put a permanent location marker at the site.
30 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Establish a permanent location marker: After selecting a site, place a brightly

colored marker (wood or metal stake) in the infestation. The stake must be

tall—about 6 ft (2 m)—and clearly visible to mark the exact location of the

release site. If possible, record the global positioning system (GPS) coordinates

of the marker.

Establish a photo point: Photographs taken annually from the same location can

effectively illustrate the success of a control program. Refer to Section 6 for

detailed instructions on establishing a photo point.

Prepare a map: A map of the infestation is helpful to visually assess the size and

distribution of purple loosestrife at the site before biocontrol agents are released.

A detailed map and written directions to the release site are essential for others

to locate the site: note permanent roads, creeks, rivers, mile markers, etc. on the

map and in the directions. If possible, include a legal description and GPS

coordinates so that the site can be easily re-located.

Monitor baseline vegetation: It is highly recommended that you assess the

amount of purple loosestrife and other vegetation at the release site before

releasing the biocontrol agents. Pre-release monitoring provides baseline data,

allows meaningful before-and-after comparisons, and will provides important

information on the effectiveness of the biocontrol program (see Section 5.2 for

information on vegetation monitoring).

3. Obtaining Purple Loosestrife Biocontrol Agents

Biocontrol insects are obtained either by collecting them (yourself or by a cooperator), rearing them, or purchasing them from a commercial supplier. Consider the

following when planning your purple loosestrife biocontrol program:

 • Field collecting the biocontrol agents provides robust and healthy insects, and is

the preferred method for obtaining the Galerucella species and Nanophyes. If a

cooperator is field collecting the insects for you, be sure they collect the agents

at the right time of year and under the best conditions, and send you clean,

sorted insects as soon as possible. Be sure cooperators know well in advance

when you need the biocontrol agents for release.

• Opportunities for collecting the root feeder, Hylobius, are at present limited

because it is not widely established in the field and population levels are low

where it is established. This weevil is best obtained from cooperators who

maintain field insectaries, or purchased from suppliers who rear them.

• Commercial suppliers provide clean, healthy insects. However, purchasing the

insects can be expensive. While some suppliers charge as little as $0.10 per

beetle, others charge as much as $0.70 per beetle for the Galerucella leaf

beetles. Please remember that different prices may also mean different quality

and make sure you know under what conditions the insects you purchase were
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 31

Figure 25. Non-waxed paper insect containers.

(UGA1291025)

raised or collected. Field-collected beetles are of superior quality when compared to lab-reared individuals, and obtaining adults immediately after they reappear from overwintering will allow you to release individuals with maximum

reproductive potential. Nanophyes and Hylobius are even more expensive.

Make sure you know the origin of your insects when making purchasing decisions.

3.1 Collecting purple loosestrife biocontrol agents

General Collecting Guidelines

This section provides information on collecting, rearing and purchasing purple loosestrife biocontrol agents with emphasis on the two Galerucella species and

Nanophyes. Hylobius is more difficult to collect.

All purple loosestrife beetles insects are most efficiently collected as adults. Planning

your collecting activities is important: know how to identify the biocontrol agents,

time the collection, prepare equipment and supplies, and train personnel in identification and collection techniques. Follow these general guidelines when planning your

collection activities:

Containers. Containers must provide safe environments for the insects while still

preventing escape. Use sturdy, breathable containers that allow air flow and

will not collect condensation. An example of good containers are pint-sized,

nonwaxed ice cream cartons (Figure 25). Plastic containers can also work well

if a large hole has been cut in the lid and the hole is covered with mesh or

organdy to allow airflow into the container and minimize the buildup of condensation. Glass or metal containers are not suitable.

To prepare the containers, place

cut purple loosestrife stems with

leaves loosely in the container,

or fit a moist (but not wet) piece

of florist foam 1 inch (2.5cm)

thick and the diameter of the

container snugly at the bottom

of each container, and push cut

stems with leaves into the florist

foam. This provides shelter and

food to keep your beetles

healthy. Do not put flowers or

seeds in the container. Do not put water in the container.

After insects are collected in the field, transfer them as soon as possible into

your breathable, durable containers. Keep containers shaded and cool at all

times while collecting, sorting, counting, and transporting. Bring a large cooler

with pre-frozen ice packs to the field, and tape the ice packs to the interior side

of the cooler so that they do not roll around and crush the insect containers.
32 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 26. Collecting Galerucella calmariensis

from purple loosestrife using the tapand-funnel method. (Background:

UGA1291026; inset: UGA1291027)

Figure 27. Sweep net for collecting purple

loosestrife beetles.

Collecting Methods. Three commonly used methods to collect purple loosestrife

biocontrol agents are tap & funnel, sweep net, and aspiration methods. The

most appropriate method will depend on the density of the insect population,

available time, and available personnel.

 • Tap-and-Funnel. The tap-and-funnel method is an efficient and productive

way to collect Galerucella and Nanophyes when their populations are high.

It is used to gather large numbers of beetles in a short amount of time.

Using a stick (a shortened length of broom handle works well) or your hand,

knock the beetles from the plants into a funnel taped to a plastic bottle or

container (see Figure 26).

Then brush the insects down

the sides of the funnel and

into the plastic container.

Knocking insects into a

plastic tray also works, but

adults are very active and, in

warm weather, will quickly

fly away.

Tapping is not selective, so

other insects and spiders will

be collected along with the

biocontrol agents. These

insects must be separated

from the biocontrol agents

before shipping or otherwise

transporting the biocontrol

agents for release to a new

site. Cooling the insects (for example, for 30 minutes in a refrigerator or

cooler) before insects are sorted greatly reduces the beetles’ activity, and

makes sorting much easier. Use an aspirator (described below) to sort the

beetles.

 • Sweep net. A sweep net is made of a cotton or muslin bag on a hoop, 15

inches (38 cm) in diameter, attached to a handle 3 feet (0.9 m) long (Figure

27). As its name implies, it is generally used to “sweep” adult insects off a

plant.

Using a sweep net produces a

‘cleaner’ catch, reducing the need

for elaborate sorting. However,

sweeping purple loosestrife with a

net is difficult and inefficient

because woody stems from

previous growing seasons interfere with sweeping the current

year’s growth, where insects are

active.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 33

Figure 29. Galerucella calmariensis collected

in aspirators. (UGA1291029)

KEEP INSECTS SHADED AND COOL WHILE

SORTING, COUNTING, AND TRANSPORTING THEM

A more effective way to use a sweep net is to bend the purple loosestrife

flower heads into the net and shake the plants to dislodge adults into the net.

This method works especially well for Nanopyhes, and when Galerucella

populations are low. The ‘catch’ must still be sorted before placing the

biocontrol agents into containers.

 • Aspirator: An aspirator is a device used to

suck insects from a surface into a collection

vial. An aspirator (Figures 28 and 29) is

used to collect insects out of a sweep net or

off a sorting tray—though it can also be

used to take insects directly from the plants.

Aspirating is easy and selective, and is the

preferred method to sort insects.

Sorting separates the biocontrol

agents from unwanted insects,

other organisms and debris,

such as weed seeds, collected

along with the beetles. Empty

the contents of the net or

collecting container onto a tray

and aspirate the purple loosestrife beetles out of the debris.

If the collected material is first

chilled, the insects will move

slower and will be easier to

catch.

Specific Collecting Guidelines

Collect biocontrol agents from field insectaries or from open field sites having an

abundance of insects. Collect adults at the beginning of their peak emergence times,

when female beetles have their maximum oviposition potential, and are most likely to

establish thriving populations at the site where they are later released. Emergence

(the optimal time for collection) will vary from region to region and year to year. For

example, Galerucella can be collected as early as mid-April in warm, western locations, and as late as early June in cooler, eastern locations. You may need to contact

your state biocontrol expert, county weed superintendent, or university extension

educator to identify the best collection sites and times. Approximate recommended

collection times are provided in Table 6.

Figure 28. Aspirator used

to collect purple

loosestrife beetles.
34 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Table 6. Methods and timetable for collecting purple loosestrife biocontrol agents.

Agent What to Collect When to Collect How to Collect

Galerucella calmariensis

and G. pusilla

Adults Mid-May to early June and

again from early to late July.

Tap & funnel, sweep net,

aspirating.

Hylobius transversovittatus Adults Late June to late August. Use sweep net to knock

individually beetles into net,

or catch beetles dropping off

plants; handpick under

leaves at ground level.

Nanophyes marmoratus Adults Late June to early July and

again mid-August.

Sweep net, tap & funnel.

Wait for a day with good weather. Do not collect in the rain: insects will hide and

become difficult to find in rainy weather, and excess moisture causes health problems—beetles may also drown in wet collection containers. The only exception to

this rule is the root feeder Hylobius, for which overcast and rainy days are optimal for

collecting the generally night-active adults.

Leaf beetles (Galerucella): Adults are easily collected with a funnel or sweep net

during the warm part of the day when they are most active. Aspirating is also a

suitable, although slower, method for collecting adults. The best time to collect

adult beetles is in mid-May to early June, when they have emerged from overwintering sites and are actively feeding, congregating, and mating. The second

period of activity occurs from early July to August, when the next generation of

adults emerge. Larvae or eggs are not generally collected because of extremely

high mortality rates during transportation.

Flower weevil (Nanophyes): Nanophyes adults are easily collected by bending and

shaking the developing purple loosestrife inflorescences over a sweep net,

dislodging the beetles into the net. Aspirating individual adults or mating pairs

from plants is possible but slow and laborious. Collect Nanopyhes during the

heat of the day—most appropriate collection times are when inflorescences

begin to form but before plants begin to flower—mating pairs congregate at the

top of these plants, and are easily seen. Depending on the location of the site,

the collecting period is generally about late June to mid-August.

Root weevil (Hylobius): Hylobius is the most difficult of the purple loosestrife

biocontrol agents to collect because it is generally nocturnal or only active on

rainy or overcast days. Also, population numbers are currently still low, so field

collecting is limited. Where it is possible to collect, do so in the early evening or

at night with a flashlight. Weevils are most easily collected by locating an adult

on a plant, carefully approaching the plant, placing a sweep net under the stem,

and allowing the beetle to drop into the net (they quickly drop from the plant

when they sense your presence). Adults can also be collected at the base of the

plant by removing the leaf litter and handpicking individual beetles, but this

activity is very time-consuming, and will only yield good results at high weevil

densities. Adults can be collected from late June to late August. (Note: because
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 35

Hylobius is not widely established at present, it will be necessary to purchase

the weevils from rearing operations until field populations have built up sufficiently to allow collection.)

3.2 Rearing purple loosestrife biocontrol agents

Programs to rear purple loosestrife biocontrol agents have focused primarily on the

Galerucella leaf beetles because they are relatively simple to rear. Rearing enables

large numbers of beetles to be rapidly produced and distributed. In many parts of the

United States and Canada, communities, agencies, youth groups, and schools have

developed mass rearing programs to help distribute the beetles throughout their states

and regions and to provide opportunities for public awareness and education.

You can find many examples of state programs on the internet. For example, the

Illinois Natural History Survey (http://www.inhs.uiuc.edu/cee/loosestrife/bcpl.html)

manages a very successful rearing program with elementary and high schools. The

Vermont Purple Loosestrife Biocontrol Program has hosted a volunteer community

rearing program of Galerucella beetles for several years (http://www.anr.state.vt.us/

dec/waterq/ans/plpage.htm). Other active programs are found in Michigan (http://

www.miseagrant.org/pp), and Minnesota (http://www.seagrant.umn.edu/exotics/

purple.html). For additional information about rearing purple loosestrife biocontrol

beetles, visit the internet web sites listed in the Selected References section.

General Galerucella Rearing Guidelines

We focus in this guide on rearing the Galerucella leaf beetles. The methods outlined

here also work well for Nanophyes, except that adult weevils are introduced when

plants begin to form flower buds (by mid-summer). Rearing Hylobius is not recommended because it is comparatively slow and usually requires highly specialized

facilities or large numbers of plants.

• Obtain plants: In early spring before plants sprout, dig about 100 mature

purple loosestrife roots, each with at least five or six stems. Take the roots to

your rearing location and pot them into plastic 4-gallon (3.8 l) pots filled with

standard commercial potting mix and a slow-release fertilizer. Place up to 12

pots in a plastic wading pool about 6 feet (2 m) in diameter. Fill the pool with 4

inches of water to simulate a wetland environment (Figure 30). Check the

water daily and refill as needed throughout the growing period. If wading pools

of the proper size aren’t available, construct a pool using pond liner or thick

plastic sheeting that can hold water to keep plants moist and healthy.

• Cover plants: Place a 4- to 5-foot (1.2 – 1.5 m) tall tomato cage over the pot (if

you intend to rear Nanophyes, these cages will need to be taller, to allow the

plants room to develop inflorescences), and cover the cages with fine mesh

netting (no-see-um netting works well). Secure the top and bottom of the

netting with twine, tape or heavy rubber bands: this will keep the beetles in the

cage and prevent entry of aphids or other pests and predators that might interfere with plant or beetle growth.
36 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

• Introduce beetles: When

plants are about 1 foot

(30cm) tall, place 10 to 15

beetles in each cage (use only

plants that produce an abundance of healthy shoots). Be

sure to put only one beetle

species in each cage. If you

rear Nanophyes, place six to

ten individuals in each cage.

Adults will feed for a few

days then begin mating and

laying eggs. Galerucella,

while small at first, will be

obvious in a few weeks.

Development (from egg to

adult) takes approximately 30-40 days, and new adult beetles will begin to

appear and congregate near the top of the plants. Nanophyes larvae will be

concealed inside the bud. Each large plant yields between 500 and 2,000

Galerucella beetles or 300 Nanophyes adults. Make sure the newly-emerged

adult beetles have sufficient foliage to feed.

• Transport beetles after rearing: Transport the newly reared beetles in the

covered, potted plants to the release site and place them next to healthy, wild

purple loosestrife plants. Remove the net bag and the wire cage; gently shake

the net bag to dislodge any beetles remaining in the bag. Remove the plant from

the pot and rest it on the ground in the infestation; this allows the beetles to

disperse on their own. Record the location of the site, the weather conditions at

the time of release and, if possible, record the GPS coordinates or legal description of the release site. Use the Purple Loosestrife Biocontrol Release Form to

record the release.

• Overwintering potted plants and beetles: It is quite easy to overwinter beetles

outdoors to have a large supply for the next year. Retain a portion of the reared

beetles on large, caged plants removed from the wading pool. Make sure they

have sufficient high-quality food; beetles will feed for a while and disappear into

the duff at the base of the plant, where they will remain until spring. To maximize plant and beetle survival, thoroughly mulch and shade the plants throughout the fall and winter. Other elaborate and specialized rearing programs use

large cages (Figure 31) or greenhouses (Figure 32) to mass-produce adult

beetles, but such programs are expensive and labor-intensive.

Figure 30. Wading pools used to grow purple

loosestrife and to rear Galerucella

calmariensis. (UGA1291030)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 37

Rearing Hylobius on semi-artificial diet

An alternative mass rearing method using a semi-artificial diet has been developed for

Hylobius. While not widely used in weed biocontrol, rearing insects on artificial diet

is a well-established practice in agricultural pest management. The semi-artificial

diet, which has the consistency of stiff jelly, is comprised of multiple ingredients, but

most importantly contains ground purple loosestrife roots. Root weevil larvae are

reared individually on diet in small containers. They complete development in three

months instead of one-to-two years under natural conditions in the field.

Advantages of artificial diet:

- Development time is reduced from one-to-two years to three months

- Eliminates slow, tedious field collection

- Large numbers of beetles can be reared

- Enables year-round beetle rearing

Disadvantages of artificial diet:

- Expense

- Requires specialized equipment and skill

See the article by Blossey et al. (2000), cited in the Selected References section, for

information on use of a semi-artificial diet to rear Hylobius.

Questions to ask suppliers

• Does the supplier have a valid USDA-APHIS permit?

• Are the agents field-collected?

• How will the agents be shipped?

• How long will the agents be held in transport?

Figure 31. Large mesh cages of potted

purple loosestrife for rearing

biocontrol agents. (UGA1291031)

Figure 32. Mesh-covered purple loosestrife

plants in a greenhouse used to rear

biocontrol agents. (UGA1291032)
38 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________ :

Supplies for transportation

• Sturdy, breathable containers

• Masking tape

• Paper towel or styrofoam

• Cooler

• Frozen ice packs

• Cardboard box (for shipping)

3.3 Purchasing purple loosestrife biocontrol agents

When purchasing biocontrol agents from a commercial supplier or when obtaining

insects from a cooperator, it is important to ensure that the insects are healthy and

received in good condition. It is also important to obtain the biocontrol agents at the

correct time of year. Be sure also to have the correct permits for interstate transportation of insects. For more information or to find a commercial supplier, contact your

cooperative weed management area, your county weed control superintendent, or

your state biocontrol of weeds expert.

4. Handling and Releasing Purple Loosestrife Biocontrol Agents

How the insects are handled and transported after they are reared or collected will

affect whether they survive at the new site. This section includes guidelines for

handling, shipping, and releasing biocontrol agents.

4.1 Handling purple loosestrife biocontrol agents

Containers. Refer to Section 3.1

for a description of suitable

containers. It is important to

use breathable containers to

have air flow to the insects and

to prevent condensation. Seal

the container with tape and

label the container with the

name of the biocontrol agent,

the quantity of weevils, the

collection site, and the date.

Transportation. To minimize stress and harm to beetles, transport and release

them as soon as possible (preferably within 24 hours). Ensure insects have

plenty of fresh food at all times. Keep containers cool and dry during transportation. Put the containers in a cooler with ice packs secured to the bottom or

sides of the cooler. Cover the ice packs with newspaper to prevent direct cold

and condensation from contacting the containers. Adult beetles can survive a

few days in a refrigerator if necessary, but keep storage time to a minimum.

4.2 Shipping purple loosestrife biocontrol agents

To ship biocontrol agents, plan the route and timing of shipments to prevent undue

delays and stress on the insects. Collect the insects early in the week and ship right

away by overnight courier (for example, FedEx, UPS, or DHL) to be sure they arrive

before the weekend. Instruct your cooperator(s) to release the insects immediately

upon receipt. Observe the following general guidelines:
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 39

Common mistakes in transportation

• Excess heat. Do not expose packaged or containerized

biocontrol agents to direct heat or sunlight.

• Excess moisture. Do not put water into the containers.

• Lack of air. Use only breathable or vented containers.

• Mortality. Provide insects with sufficient food. Do not

store insects more than three days.

• Know the regulations: It is important to know the regulations pertaining to

shipping biocontrol agents across county or state borders. Interstate transportation permits may be required. To learn the current regulations, contact your

local cooperative weed management area, state department of agriculture, or the

USDA Animal and Plant Health Inspection Service–Plant Protection and

Quarantine office (USDA-APHIS-PPQ) (http://www.aphis.usda.gov/ppq).

• Prepare the insects: Prepare the insects right before the scheduled shipment to

minimize stress. Follow these steps:

 - Separate beetles from all other unwanted material, such as other insects,

spiders, weed seeds, etc.

 - Put the beetles in breathable or vented shipping containers (described

above).

 - Pack the containers in an insulated shipping box (Figure 33) with a frozen

ice pack well secured to the inside. Seal each frozen ice pack in a plastic

freezer bag to prevent condensation inside the box as the ice pack melts.

Figure 33. Shipping box for purple loosestrife

beetles. (UGA1291033)
40 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

4.3 Releasing purple loosestrife biocontrol agents

There are many factors that can determine whether insects establish and flourish at a

release site. Few of these are under control by humans (weather, wildfire, etc.), but

follow these general steps for releasing biocontrol agents to give the insects the best

start possible:

• Timing the release: Release the beetles at the appropriate growth stage of

purple loosestrife. For example, when releasing Nanophyes, purple loosestrife

should be at or near the flowering stage. If most plants are beyond the flowering stage, it is too late to release at that site. Locate a different infestation,

perhaps at a higher elevation, that is at the flowering stage.

• Number of biocontrol agents to release per site: The number of insects to

release per site depends on; 1) the insect species, 2) resources available to

collect, 3) the time of year.

 - For Galerucella: it is possible to collect large numbers of beetles (several

thousand), thus a release of 1,000 beetles is possible. But even releases of

200 adults in the spring have yielded good results. When collecting from the

summer generation, a minimum release of 2,000 Galerucella is recommended.

- For Nanophyes: at high densities, it is possible to collect several hundred

beetles in an hour. A minimum release of 200 adults per site is recommended.

- For Hylobius: it is more difficult and labor intensive (or expensive) to obtain

Hylobius, but a release of at least 100 beetles is recommended.

• Release of biocontrol agents: Release insects as soon as possible after you

receive them; do not wait for good weather (but avoid heavy downpours).

Release in the early morning hours between 6 and 10 a.m. or in the cooler

evening hours between 6 and 10 p.m.; biocontrol agents are less likely to scatter

if released at cooler times of the day. In general, you can release insects either

in cages or make open releases. Caged releases prevent immediate dispersal of

insects but require you to put up and take down equipment.

For open releases, get to the desired release location, open shipment containers,

and gently shake all insects, purple loosestrife stems, and florist foam at the base

of a vigorously growing purple loosestrife plant. Do not release over water, but

at the shore or on dry land if possible. Release all the insects at once at a single

location; do not disperse them at the site, as insects will naturally disperse on

their own.

For caged releases, place a mesh or organdy bag over a plant (Figure 34), release

insects into the caged plant, and tie the bottom of the bag to the stem. Cages

confine the insects for a period of time so they adjust to the site and easily find

one another, but cages need to be removed within a few days.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 41

Figure 34. Releasing Nanophyes

marmoratus on caged

purple loosestrife.

(UGA1291034)

• Frequency of release: Often, a single

release will be sufficient to establish an

insect population, but more than one release

may be necessary if previous releases failed.

Do not get discouraged, and bear in mind

that it could take two or more years to

determine if the agent released (especially

Hylobius) successfully established.

• Releasing multiple species of agents: As a

rule, release only one biocontrol agent if

you plan to establish a field collection site.

Locate release sites at least 2 miles (3 km)

apart. At other sites, you can freely mix

species to assess how control is influenced

by different insect combinations. Be aware

that insects will migrate and establish new

populations over time.

• Place the permanent location marker:

Place the marker at the location of the

insect release. This location will be later

used to relocate the site and for monitoring

activities.

• Take photos: Take a series of photographs to record the release (see Section 6).

• Fill out and submit a release form: Complete the Purple Loosestrife Biocontrol

Release Form (see Appendix). Submit the form to your county weed superintendent, cooperative weed management area, or university or state biocontrol

expert. Keep a copy for your records.

Summary: Handling and Releasing Purple Loosestrife Biocontrol

Agents

• Use sturdy, breathable containers with food according to instructions.

• Sort insects before packaging them to ensure that predators (e.g., spiders) or

weed seeds are not trapped inside the containers.

• Avoid physical damage to the biocontrol agents by taping down ice packs.

• Keep insects cool during transportation.

• If release or shipping is not immediate, store the insects in refrigerators no

colder than 40 to 50o F (4 to 10oC) for no longer than three days, or keep

them in an ice chest until they are ready to be shipped or transported.

• Release during the cool times of the day; do not wait for good weather.

• Take photos; fill out the Purple Loosestrife Biocontrol Release Form (see

Appendix).
42 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 35. Purple loosestrife infestation: a) before (1998) and b) after (2003) control by

Galerucella beetles. (Left to right: UGA1291035 and UGA1291036)

5. Monitoring

The purpose of monitoring is to evaluate the success of your purple loosestrife

biocontrol program and to determine if you are meeting your purple loosestrife

biocontrol goals. Monitoring activities use standardized procedures over time to

assess changes in populations of the biocontrol agents, purple loosestrife, and the

wetland communities.

Monitoring can answer questions about whether a) the beetles have become established at the release site, b) the beetle populations are increasing or declining, c) the

beetles have spread from the initial release site, and d) the beetles are having an

impact on purple loosestrife in the wetland plant community.

Monitoring methods can be simple or complex. Basic assessments can be done with a

minimum of time and effort each year. The duration of monitoring can also vary,

from a single year to demonstrate the biocontrol agents established, to multiple years

to follow the population of the biocontrol agent(s), the decline of purple loosestrife,

and changes in the overall plant community.

Qualitative monitoring

Qualitative monitoring is based on subjective assessments. It can include recording

the presence or absence of insects, estimating the amount of plant damage, estimating

the distribution or density of purple loosestrife at the site, or making observations

about wildlife at the release site over time. Another qualitative assessment is beforeand-after photographs (Figure 35), which is a photo record of the site before or at the

time beetles are released that is repeated at one- or two-year intervals. Because of its

descriptive nature, qualitative monitoring tends to be less time-, labor-, and supplyintensive than quantitative monitoring. The descriptive nature of qualitative monitoring does not readily allow for detailed statistical analysis; however, if sufficiently

detailed qualitative data is collected, useful information can still be derived. Data

obtained from qualitative monitoring may guide more intensive monitoring in the

future.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 43

Questions to Ask in a Monitoring Program

• Have the biocontrol agents successfully established populations at the site?

• Are the beetle populations increasing or declining?

• How far have biocontrol agents spread from the initial release site(s)?

• Are the biocontrol agents found in sufficient number to be collected and distributed?

• Are the biocontrol agents causing visible damage to the target weed?

• Is the purple loosestrife declining at the site?

• Are changes occurring within the plant community?

Answers to these questions will allow land managers to do the following:

• Establish that biocontrol agents are impacting the target weed.

• Determine if supplemental biocontrol agent releases or other weed management activities

are needed.

• Document changes in the plant community.

Quantitative monitoring

Quantitative monitoring is based on measurements, and is used to record and measure

changes in a specific population over time. Quantitative monitoring can be as simple

as counting the number of insects per unit area, counting the number of flowering

purple loosestrife stems in a given area, counting insects and buds, estimating degree

of leaf feeding damage by adults and larvae, counting and measuring plants, or even

quantifying bird, mammal, and amphibian populations over time. More detailed

quantitative monitoring of purple loosestrife can include measuring height, seed

production, biomass per unit area, plant community diversity, or even a record of

birds, amphibians, or mammals in the study area to determine the faunal diversity

associated with the plant community. Although quantitative monitoring may take

more time to plan and implement, and also requires more specialized skills and training than qualitative monitoring, the data obtained from a properly designed quantitative monitoring system can be analyzed statistically.

5.1 Monitoring Purple Loosestrife and its Biocontrol Agents

Before you begin your monitoring program, it is essential to outline your long-term

monitoring objectives. It is important to know, before you begin, what and how

much data will be collected. Be sure you have the necessary resources, trained

personnel, and equipment to conduct the monitoring. Follow these additional steps:
44 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

• Choose sites to monitor: Select sites that are accessible and have a dense

infestation of purple loosestrife (Figure 36). Be sure the site will be available to

you to monitor for at least three to five years after release. Begin monitoring

where the insects were first released, as this is where the highest density of

biocontrol agents are likely to occur and where changes to the purple loosestrife

are more likely first to be detected.

• Schedule monitoring activities: Schedule monitoring activities at the same time

each year to enable comparison of year-to-year conditions. The recommended

quantitative monitoring protocol outlined below requires monitoring twice each

year: in the spring to monitor insect activity, and in the late summer to monitor

distribution and density of purple loosestrife and other vegetation.

• Choose a monitoring method: Select a monitoring method and plan based on

your monitoring goals, what information you want to gather, and the number of

sites you intend to monitor. Consider the Questions to Ask (in box below) and

the Monitoring Plan Questionnaire (see Appendix) to help determine the goals

of your monitoring program.

Consider that:

 - The better you define your biocontrol program goals and monitoring strategy, the better you will be able to evaluate your success.

 - It is important to standardize monitoring procedures.

 - Monitoring only becomes useful if methods are used consistently year to

year.

 - Even a full-scale quantitative monitoring protocol can be implemented with

little effort. Once sites are established, time commitments usually require a

few hours in the spring/early summer and a few hours in the fall for each

monitoring site.

Figure 36. Purple loosestrife monitoring site. (UGA0021091)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 45

The recommended monitoring protocol described below is intended for select

sites. If you manage a number of release sites, or if you do not have the time or

expertise to complete the entire monitoring protocol as outlined, a more qualitative monitoring is recommended. A less intensive monitoring scheme is provided in Table 7. The categories involve “quick” scoring schemes of the number

of biocontrol insects you observe, the amount of purple loosestrife defoliation,

and photos taken at one- to two-year intervals. Included is timing for each

activity.

• Decide when to begin monitoring biocontrol agents: Monitoring should

ideally begin the season before you release biocontrol agents (this provides

baseline data) or, at a minimum, the year of your release. Galerucella easily

colonizes a new site, especially if a large number (1,000 to 1,500 beetles) was

initially released. Nanophyes, too, easily establishes itself at sites not colonized

by Galerucella, although the population of Nanophyes is slower to build up than

Galerucella. Hylobius may take two to three years after release to be detected

(thus, if Hylobius is not found a year after the release, do not assume that it

failed to establish: revisit the site for a few more years).

5.2 Detailed Purple Loosestrife Quantitative Monitoring

The detailed protocol outlined below is used for quantitative assessments of purple

loosestrife and its biocontrol agents. It is a standardized monitoring protocol developed by the Ecology and Management of Invasive Plant Species Program at Cornell

University (www.invasiveplants.net). The advantage of a standardized monitoring

protocol is that it allows meaningful comparisons to be made among similar programs

in different locations and regions, enables researchers and managers to evaluate the

relative success of specific purple loosestrife biocontrol programs, and perhaps helps

to understand why certain programs fail.

In this protocol, assessment locations are selected, a quadrat frame is put into place

and marked with stakes, quantitative data are taken, and then the frame (but not the

Table 7. A rapid assessment scheme to monitor purple loosestrife and its biocontrol agents.

Monitoring Subject Time to Observe Objective/Method

Galerucella pusilla and

G. calmariensis

Mid-May to mid-June Are eggs, adults, larvae present on the

plant? Observe and count.

Nanophyes marmoratus Late May to mid-July Are adults present? Dissect seedheads

and determine if larvae are present.

Hylobius transversovittatus Late June to August Are adults present? Excavate and

dissect roots.

Defoliation Mid-July Estimate how much purple loosestrife

foliage has been removed or is dead.

Other plants August Record other plants and their

abundance.
46 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

stakes) are taken to the next assessment location. Leaving the marking stakes in place

allows the monitoring team to perform the same assessment at the same locations in

subsequent years.

Follow these steps to begin a quantitative monitoring program:

1. Collect materials.

For each quadrat frame:

• Two 10-foot lengths of 3⁄4-inch PVC or CPVC pipe, cut into two 1-m

lengths and four 0.5-m lengths

• Four right-angle elbows and two straight-line connectors for the PVC or

CPVC pipe

• PVC glue (a half-pint is enough for several frames)

• One can of spray foam insulation—optional (one can is enough for several

frames)

Other materials, supplies, and tools:

• 1-meter measuring sticks

• 50-m measuring tape

• Four plastic or galvanized metal stakes (galvanized metal electric conduit or

PVC pipe are inexpensive and readily available at hardware stores)

• Hammer

• Permanent marker

• Compass

• Handheld GPS receiver (if available)

• Camera

• Stopwatch

• Clipboard, pencils, and pen

• Forms 1 to 4 (see Appendix)

Figure 37 shows many of the materials needed for this monitoring method.

2. Construct a sampling quadrat.

We recommend using a two-piece quadrat frame composed of two short Ushaped halves that slide together to form a square. The frame can be filled with

foam insulation to create a floating quadrat for use in flooded sites.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 47

The inside dimensions of the finished frame should measure 1m by 1m. After

cutting the pipe to the correct lengths, glue two elbows to each 1m-long piece

(make sure the elbows are perfectly aligned with each other). Then, glue each

elbow to a 0.5m-long piece to form two open U-shaped half-frames. Glue the

connectors to the short sides of ONE of these half-frames (the connectors will

hold the frame together while being used). Using a permanent marker, mark 10

cm intervals on each side of the frame pipe to assist with estimating percent

cover.

3. Record site location.

Using Form 1: Purple Loosestrife Biocontrol Monitoring–Site Location (see

Appendix), describe the monitoring site, and include a sketched map and a

vegetation diagram. Record the position and numbers of the quadrats on the

vegetation map.

4. Determine quadrat locations and set up the frame at field sites.

Quadrats should be placed at random into the purple loosestrife infestation.

ALL quadrats must initially contain purple loosestrife; if necessary, shift the

location of the quadrat so that purple loosestrife covers at least 30 percent of the

quadrat. Various methods are available to randomize the quadrat placement.

The easiest is a transect, a straight line running through the vegetation. Quadrats are placed at predetermined intervals (e.g., every 5, 10, or 20 meters) along

the transect line. To do so:

• Locate the beginning of the transect at least 15 ft (5m) from an edge (i.e.,

roadside, streambank, field).

• Using the 50m measuring tape, stretch the tape in a straight line through the

vegetation, being careful not to overly trample the vegetation.

Figure 37. Supplies needed to monitor purple loosestrife: a) meter-sticks,

b) measuring tape, c) stopwatch, d) camera, e) compass,

f) GPS, g) clipboard and writing instruments, and h) frame

components. (UGA1291037)
48 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figure 38. Quadrat set within a purple loosestrife

infestation. (UGA1291038)

• Secure the two ends of the transect with a stake to hold it in place while the

quadrats are established.

At each site, have 5-10 quadrats. Keep in mind that more quadrats are better.

Knowing how many quadrats you will have at a site, determine the distance

between quadrats (e.g. 5, 10m) there will be along the transect.

• Starting from one end of the transect, locate the position of the first quadrat

on the transect.

• Place the quadrat frame into the vegetation by sliding the arms of the first

U-shaped frame through the vegetation and as close to the ground as possible, moving carefully to avoid disturbing any insects on the vegetation.

Then, gently slide the second half of the frame into the vegetation from the

opposite direction and attach it to the first half, completing the 1m2

 frame.

Avoid trampling vegetation in and near the quadrat.

• At one corner of the quadrat drive a 5-8 ft (1-2m) long plastic pipe or

galvanized steel stake into the ground (galvanized metal electric conduit or

PVC pipe are inexpensive and readily available at hardware stores). Mark

each quadrat the same and note which corner is staked. This will allow

exact placement of the quadrat in future years. Allow the pipe or stake to

stick up high enough to be seen, but low enough to minimize vandalism.

Write the quadrat number on each marker, and, if possible, record the GPS

coordinates of each quadrat. Flagging tape will also help to relocate the

quadrat in the future. Figure 38 shows a typical quadrat placement.

When you complete monitoring and recording data for the first quadrat, disassemble the frame and set it up at the next quadrat location along the transect.

Repeat this until all the quadrats have been placed, marked with a stake, and the

monitoring information is recorded. When the monitoring is complete for the
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 49

site, remove the transect measuring tape, leaving only the quadrat markers

behind. The same set of quadrats can be used year after year. This allows

statistical analysis to be conducted on purple loosestrife density, the abundance

of biocontrol insects, and the changes in purple loosestrife and other vegetation.

5. Monitor biocontrol agents.

Using Form 2: Purple Loosestrife Biocontrol Monitoring–Insect Monitoring and

Instructions (see Appendix), evaluate the biocontrol agents on plants within

each quadrat. The protocol involves the following:

• Visually count biocontrol agents: For each agent, count for one minute the

number of beetles you see on plants in each quadrat. If more that one

species is at the site, count one minute for each species. For Galerucella,

where multiple life stages are present at a time, count for one minute, each,

the number of adults, larvae, and eggs.

• Estimate feeding damage: In addition to counting insects, it is useful to

look for signs of feeding damage. Estimate the amount of foliage that has

been damaged or eaten by adults (and Galerucella larvae) feeding on foliage.

• Estimate cover of purple loosestrife: Looking over the quadrat, estimate

the percent of the quadrat that is covered by purple loosestrife.

• Make observations: Observe the insects feeding and note their activity.

6. Purple loosestrife and other vegetation.

Purple loosestrife should be monitored before biocontrol agents are released. It

is important to know the size and density of the purple loosestrife infestation

before biocontrol is implemented as it gives managers baseline data against

which future monitoring data will be compared. Monitor sites once a year or

every other year. Purple loosestrife, and other vegetation, is evaluated within a

quadrat set up as described above. Using Form 3: Purple Loosestrife Biocontrol

Monitoring–Vegetation Monitoring and Instructions (see Appendix), do the

following:

• Visual estimates: Visually estimate how much of the quadrat is covered

with purple loosestrife and other vegetation such as cattails and shrubs,

expressed as a percentage (Figure 39). Personnel may have to be trained in

estimating cover percentage.

• Stem counts: Count the number of purple loosestrife and cattail (or other

dominant vegetation) stems in the quadrat. Count the total number of

inflorescences in the quadrat.
50 Chapter 3: Developing a Purple Loosestrife Biological Control Program

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

• Measure a sample of stems: Select the five tallest stems in the quadrat to

measure. For each stem, measure height, number of inflorescences (on main

stem and branches), and length of longest inflorescence. To count the

number of flowers, remove the central 2-inch (5-cm) portion of the inflorescence and count the number of flowers and buds. These data enable you to

evaluate how individual plants in the infestation are being affected by biological control.

• Make observations: Note any special features about the site or any changes

at the site since the last examination, such as disturbance, fire, flooding,

grazing, and bird nesting activity (or lack thereof).

• Monitor other vegetation: Use Form 4: Purple Loosestrife Biocontrol

Monitoring–Associated Vegetation (see Appendix) to record other vegetation within the quadrat in the plant community. This form is used to track

changes in the composition of the plant community as purple loosestrife

declines.

Figure 39. Estimating purple loosestrife coverage.

(UGA1291039)
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

Chapter 3: Developing a Purple Loosestrife Biological Control Program 51

6. Establishing a Photo Point for Monitoring

Photographs of the release site are a valuable qualitative assessment tool. Photos taken annually from a designated photo point can provide a visual record of

trends or changes in the vegetation at the site over time, though it does not

necessarily show their causes. Thus, photographs are best used in conjunction

with other monitoring techniques.

When setting up a photo point, consider the following:

• Always take photographs at the same time of year. Choose the time of year

to take the first set of photographs; flowering stages are ideal because of the

contrast between flowers and the surrounding vegetation. Taking photographs once a year is sufficient, but it may prove useful to take pictures of

the site more frequently.

 • Always take photographs from the same direction and at approximately the

same time of day.

 • Determine the location of the photo point when you establish the release

site. If possible, chose a location from which to take photographs that

overlooks a large portion of the purple loosestrife infestation.

 • Set a colorful metal stake in the infestation as a photo point marker. Include

the marker in the photographs. Note and document the location of the

photo point marker to find it if it is obscured by vegetation.

• Label images (slides, prints, or digital filenames) clearly, with the year that

the photograph was taken.

Supplies for taking photos

• Camera (digital or 35 mm with color film)

• Notebook and forms

• Previous year’s photo (for reference)

• Metal post

• Bright-colored spray paint
52 Selected References

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

SELECTED REFERENCES

Purple Loosestrife Biology and Ecology

Blossey, B., L. Skinner, and J. Taylor. 2001. Impact and management of purple

loosestrife in North America. Biodiversity and Conservation 10: 1787-1807.

Correll, D.S. and H.B. Correll. 1995. Aquatic and Wetland Plants of the Southwestern United States. Stanford University Press. Stanford, California.

Cronquist, A., N.H. Holmgren, and P.K. Holmgren. 1997. Intermountain Flora,

Vol. 3. New York Botanical Society, New York.

Emery, S.L., and J.A. Perry. 1995. Above-ground biomass and phosphorus concentrations of Lythrum salicaria (purple loosestrife) and Typha spp. (cattail) in

12 Minnesota wetlands. American Midland Naturalist 134:394-399.

Emery, S.L., and J.A. Perry. 1996. Decomposition rates and phosphorus concentrations of purple loosestrife (L. salicaria) and cattail (Typha spp.) in fourteen

Minnesota wetlands. Hydrobiologia 323: 129-138.

Farnesworth, E.J., and D.R. Ellis. 2001. Is purple loosestrife (Lythrum salicaria)

an invasive threat to freshwater wetlands? Conflicting evidence from several

ecological metrics. Wetlands. 21: 199-209.

Heidorn, R., and B. Anderson. 1991. Vegetation management guideline: purple

loosestrife (Lythrum salicaria L.). Natural Areas Journal 11(3): 172-173.

Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist’s

manual: Illustrations of the Vascular Plants of Northeastern United States and

Adjacent Canada. New York Botanical Society. New York.

Gabor, T. S., T. Haagsma, and H.R. Murkin. 1996. Wetland plant responses to

varying degrees of purple loosestrife removal in southeastern Ontario, Canada.

Wetlands 16: 95-98.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

SELECTED REFERENCES 53

Grout, J.A., C.D. Levings, and J.S. Richardson. 1997. Decomposition rates of

purple loosestrife (Lythrum salicaria) and Lyngbyei’s sedge (Carex lyngbyei) in

the Fraser River Estuary. Estuaries 20: 96-102.

Mal, T.K., J. Lovett-Doust, and L. Lovett-Doust. 1997. Time-dependent competitive displacement of Typha angustifolia by L. salicaria. Oikos 79: 26-33.

Mal, T. K., J. Lovett-Doust, L. Lovett-Doust, and F. A. Mulligan. 1992. The

biology of Canadian weeds. Article 100: Lythrum salicaria. Canadian Journal

of Plant Science 72: 1305-1330.

McCaughey, T.L., and G. Stephenson. 2000. Time from flowering to seed viability

in purple loosestrife (Lythrum salicaria). Aquatic Botany 66: 57-68.

Nötzold, R., B. Blossey, and E. Newton. 1998. The influence of below-ground

herbivory and plant competition on growth and biomass allocation of purple

loosestrife. Oecologia 113: 82-93.

Nyvall, R.F. 1995. Fungi associated with purple loosestrife (Lythrum salicaria) in

Minnesota. Mycologia 87: 501-506.

Rawinski, T.J., and R.A. Malecki. 1984. Ecological relationships among purple

loosestrife, cattail and wildlife at the Montezuma National Wildlife Refuge. New

York Fish and Game Journal 31: 81-87.

Stamm-Katovitch, E.J., R.L. Becker, C.C. Sheaffer, and J.L. Halgerson. 1998.

Seasonal fluctuations of carbohydrate levels in roots and crowns of purple

loosestrife (Lythrum salicaria). Weed Science 46: 540-544.

Stevens, K.J., R.L. Peterson, and G.R. Stephenson. 1997. Vegetative propagation

and the tissues involved in the lateral spread of Lythrum salicaria. Aquatic

Botany. 56: 11-24.

Thompson, D.Q., R.L. Stuckey, and E.B. Thompson. 1987. Spread, impact, and

control of purple loosestrife (L. salicaria) in North American wetlands. U.S.

Fish and Wildlife Service, Fish and Wildlife Research Report No. 2. Washington

D.C.

Wagner, W.L., D.R. Herbst, and S.H. Sohmer. 1999. Manual of the Flowering

Plants of Hawai’i. University of Hawai’i Press. Honolulu, Hawai’i.

Weihe, P.E., and R.K. Neely. 1997. The effects of shading on competition between

purple loosestrife and broad-leaved cattail. Aquatic Botany 59:127-138.

Welling, C.H., and R.L. Becker. 1990. Seed bank dynamics of Lythrum salicaria

L.: implications for control of this species in North America. Aquatic Botany

38: 303-309.
54 Selected References

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Welling, C.H., and R.L. Becker. 1993. Reduction of purple loosestrife establishment in Minnesota wetlands. Wildlife Society Bulletin 21: 56-64.

Whitt, M.B., H.H. Prince, and R.R. Cox, Jr. 1999. Avian use of purple loosestrife

dominated habitat relative to other vegetation types in a Lake Huron wetland

complex. Wilson Bulletin 111: 105-114.

Wilcox, D.A. 1989. Migration and control of purple loosestrife (Lythrum salicaria

L.) along highway corridors. Environmental Management 13 (3): 365-370.

Purple Loosestrife Biological Control

Blossey, B. 1995. A comparison of various approaches for evaluating potential

biological control agents using insects on Lythrum salicaria. Biological Control

5: 113-122.

Blossey, B., and D. Schroeder. 1995. Host specificity of three potential biological

weed control agents attacking flowers and seeds of Lythrum salicaria. Biological

Control 5: 47-53.

Hight, S.D. 1990. Available feeding niches in populations of Lythrum salicaria L.

(purple loosestrife) in the northeastern United States. Pp. 269-278 in E. S.

Delfosse (ed.), Proceedings of the VII International Symposium on the Biological Control of Weeds, March 6-11, 1988, Rome, Italy. Istituto Sperimentale de

la Patologia Vegetale (MAF), Rome, Italy.

Hight, S.D., B. Blossey, J. Laing, and R. DeClerck-Floate. 1995. Establishment of

insect biological control agents from Europe against Lythrum salicaria in North

America. Environmental Entomology 24: 967-977.

Malecki, R.A., B. Blossey, S.D. Hight, D. Schroeder, L.T. Kok, and J.R. Coulson.

1993. Biological control of purple loosestrife. Bioscience 43: 680-686.

Nyvall, R.F., and A. Hu. 1997. Laboratory evaluation of indigenous North American fungi for biological control of purple loosestrife. Biological Control 8: 37-

42.

Piper, G.L. 1996. Biological control of the wetlands weed purple loosesetrife

(Lythrum salicaria) in the Pacific northwestern United States. Hydrobiologia

340: 291-294.

Voegtlin, D.J. 1995. Potential of Myzus lythri (Homopthera: Aphididae) to influence growth and development of Lythrum salicaria (Myrtiflorae: Lythraceae).

Environmental Entomology 24(3): 724-729.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

SELECTED REFERENCES 55

Purple Loosestrife Biological Control Agents

Blossey, B. 1993. Herbivory below ground and biological weed control: life

history of a root-boring weevil on purple loosestrife. Oecologia 94: 380-387.

Blossey, B. 1995. Coexistence of two leaf-beetles in the same fundamental niche.

Distribution, adult phenology and oviposition. Oikos 74: 225-234.

Blossey, B., and M. Schat. 1997. Performance of Galerucella calmariensis (Coleoptera: Chrysomelidae) on different North American populations of purple

loosestrife. Environmental Entomology 26: 439-445.

Blossey, B., D. Schroeder, S. D. Hight, and R. A. Malecki. 1994. Host specificity

and environmental impact of two leaf beetles (Galerucella calmariensis and G.

pusilla) for biological control of purple loosestrife (Lythrum salicaria). Weed

Science 42:134-140.

Blossey, B., D. Eberts, E. Morrison, and T.R. Hunt. 2000. Mass rearing the weevil

Hylobius transversovittatus (Coleoptera: Curculionidae), biological control of

purple loosestrife (Lythrum salicaria) on semi artificial diet. Journal of Economic Entomology 93(6): 1644-1656.

Blossey, B., R. Casagrande, L. Tewksbury, D.A. Landis, R. Wiedenmann, and

D.R. Ellis. 2001. Non-target feeding of leaf-beetles introduced to control

purple loosestrife (Lythrum salicaria). Natural Areas Journal 21: 368-377.

Corrigan, J.E., D.L. MacKenzie, and L. Simser. 1998. Field observations of nontarget feeding by Galerucella calmariensis (Coleoptera: Chrysomelidae), an

introduced biological control agent of purple loosestrife, Lythrum salicaria

(Lythraceae). Proceedings of the Entomological Society of Ontario 129: 99-106.

Grevstad, F.S., and A.L. Herzig. 1997. Quantifying the effects of distance and

conspecifics on colonization: experiments and models using the loosestrife leaf

beetle, Galerucella calmariensis. Oecologia 110: 60-68.

Kok, L.T., T.J. McAvoy, R. A. Malecki, S.D. Hight, J.J. Drea, and J.R. Coulson.

1992. Host specificity tests of Galerucella calmariensis (L.) and G. pusilla

(Duft.) (Coleoptera: Chrysomelidae), potential biological control agents of

purple loosestrife, Lythrum salicaria L (Lythraceae). Biological Control 2: 282-

290.

Manguin, S., R. White, B. Blossey, and S.D. Hight. 1993. Genetics, taxonomy, and

ecology of certain species of Galerucella (Coleoptera: Chrysomelidae). Annals

of the Entomological Society of America 86: 397-410.
56 Selected References

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

McAvoy, T.J., L.T. Kok, and W.T. Mays. 1997. Phenology of an established population of Galerucella calmariensis (L.) and G. pusilla (Duft.) (Coleoptera:

Chrysomelidae) on purple loosestrife, Lythrum salicaria L. (Lythraceae), in

southwest Virginia. Biological Control. 9:106-111.

Nechols, F.R., H.H. Obrycki, C.A. Tauber, and M.J. Tauber. 1996. Potential

impact of native natural enemies on Galerucella spp. (Coleoptera:

Chrysomelidae) imported for biological control of purple loosestrife: a field

evaluation. Biological Control 7: 60-66.

Beetle Classification

Alonso-Zarazaga, M.A., and C.H.C. Lyal. 1999. A world catalogue of families

and genera of Curculionoidea (Insecta: Colopetera) (Excepting Scolytidae and

Platypodidae). Entomopraxos. Bracelona, Spain.

Anderson, R.S., and D.G. Kissinger. 2002. Brentidae. Pg. 711-718 in: Arnett, R.

H., Jr., M. C. Thomas, P. E. Skelley and J. H. Frank, eds., American Beetles,

Volume 2: Polyphaga: Scarabaeoidea through Curculionidae. CRC Press.

Lawrence, J.F., and A.F. Newton, Jr. 1995. Families and subfamilies of Coleoptera (with selected genera, notes, references and data on family-group

names). Pp. 779-1006 in: J. Pakaluk and S. A. Slipinski. eds., Biology, Phylogeny, and Classification of Coleoptera: Papers celebrating the 80th birthday of

Roy A. Crowson. Muzeum i Instytut Zoologii PAN, Warsaw, Poland.

General Biological Control

Masters, G. J., V. K. Brown, and A. C. Gange. 1993. Plant mediated interactions

between above- and below-ground insect herbivores. Oikos 66: 148-151.

McFadyen, R. E. C. 1998. Biological control of weeds. Annual Review of Entomology 43:369-393.

Rees, N. E., P. C. Quimby, Jr., G. L. Piper, E. M. Coombs, C. E. Turner, N. R.

Spencer, and L. V. Knutson, eds. 1996. Biological Control of Weeds in the West.

Western Society of Weed Science, USDA/ARS, Montana Dept. Agric., Montana State University, Bozeman, MT.

Van Driesche, R., B. Blossey, M. Hoddle, S. Lyon, and R. Reardon. 2002. Biological Control of Invasive Plants in the Eastern United States. USDA Forest

Service Publication FHTET-2002-04, 413 pp.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

SELECTED REFERENCES 57

Other Control Methods

Comas, L., K. Edwards, and B. Lynch. 1992. Control of purple loosestrife

(Lythrum salicaria L.) at Indiana Dunes National Lakeshore by cutting followed

by overwinter flooding. National Park Serv. National Biological Survey. Wisconsin Cooperative Research Unit, 12 pp.

Haworth-Brockman, M.J., H.R. Murkin, and R.T. Clay. 1993. Effects of shallow

flooding on newly established purple loosestrife seedlings. Wetlands 13(3): 224-

227.

Malecki, R.A., and T. J. Rawinski. 1985. New methods for controlling purple

loosestrife. New York Fish and Game Journal 32(1): 9-19.

Templer, P., S. Findlay, and C. Wigand. 1998. Sediment chemistry associated with

native and non-native emergent macrophytes of a Hudson River marsh ecosystem. Wetlands 18: 70-78.

Weiher, E., I.C. Wisheu, P.A. Keddy, and D.R.J. Moore. 1996. Establishment,

persistence, and management implications of experimental wetland plant communities. Wetlands 16: 208-218.

Purple Loosestrife Internet Resources

Plant Identification

http://www.lakeheadca.com/lsstrife.htm

http://www.fs.fed.us/database/feis/plants/forb/lytsal/references.html

http://www.mobilebaynep.com/AMRAT/AMRAT%20Species.htm

http://www.entomology.wisc.edu/mbcn/fea501.html

http://www.conservation.state.mo.us/conmag/1998/08/5.html

http://www.cwma.org/prpl_losestrif.html

http://www.seagrant.umn.edu/exotics/purple.html

http://www.ext.nodak.edu/extpubs/plantsci/weeds/w1132w.htm

http://asuwlink.uwyo.edu/~caps/purple/purplels.html

http://www.colostate.edu/Depts/CoopExt/Adams/weed/loosestrife_id.htm

http://www.co.weber.ut.us/weeds/types/p_loosestrife.asp

http://www.ag.unr.edu/wsj/purpleloose.html

http://www.unce.unr.edu/publications/FS02/FS0258.pdf

http://www.minidoka.id.us/weed/noxious/purple_loosestrife.htm
58 Selected References

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

http://oregonweeds.org/weeds/weed_loosestrife.html

http://www.nwcb.wa.gov/weed_info/ploosestrife.html

http://cru.cahe.wsu.edu/CEPublications/pnw0380/pnw0380.pdf

http://dnr.metrokc.gov/wlr/pi/loosestf.htm

http://www.ecy.wa.gov/programs/wq/plants/weeds/purple_loosestrife.html

http://paipm.cas.psu.edu/Ploosestrife.htm

http://members.efn.org/~ipmpa/Noxploos.html

http://plants.usda.gov

http://www.ducks.ca/purple/

http://www.dnr.state.mn.us/ecological_services/exotics/plprog.html

http://www.miseagrant.org/pp/

http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm

http://www.hort.uconn.edu/ipm/ipmbio.htm

http://www.inhs.uiuc.edu/cee/loosestrife/bcpl.html

http://www.invasiveplants.net/InvasivePlants/PurpleLoosestrife/

PurpleLoosestrife.asp

Control and Eradication

http://www.lakeheadca.com/lsstrife.htm

http://www.entomology.wisc.edu/mbcn/fea501.html

http://tncweeds.ucdavis.edu/esadocs/lythsali.html

http://www.seagrant.umn.edu/exotics/purple.html

http://asuwlink.uwyo.edu/~caps/purple/purplels.html

http://www.colostate.edu/Depts/CoopExt/Adams/weed/loosestrife_id.htm

http://www.unce.unr.edu/publications/FS02/FS0258.pdf

http://invasives.fws.gov/Index.PT.Loosestrife.html

http://members.efn.org/~ipmpa/Noxploos.html

http://www.dnr.state.mn.us/ecological_services/exotics/plprog.html

http://www.miseagrant.org/pp/

http://www.ceris.purdue.edu/napis/states/ct/ctpls/pls1999.html

http://www.inhs.uiuc.edu/cee/loosestrife/bcpl.html
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

SELECTED REFERENCES 59

Biological Control Identification

http://www.hort.uconn.edu/ipm/general/biocntrl/looseposters1.pdf

http://www.entomology.wisc.edu/mbcn/fea501.html

http://www.wes.army.mil/el/aqua/apis/biocontrol/html/nanophye.html

http://www.ext.nodak.edu/extpubs/plantsci/weeds/w1132w.htm

http://mtwow.org/bio-control-purple-loosestrife-links.htm

http://asuwlink.uwyo.edu/~caps/purple/purplels.html

http://www.unce.unr.edu/publications/FS02/FS0258.pdf

http://www.nwcb.wa.gov/weed_info/ploosestrife.html

http://paipm.cas.psu.edu/Ploosestrife.htm

http://members.efn.org/~ipmpa/Noxploos.html

http://www.four-h.purdue.edu/download/purple/pdf/pl_promo.pdf

http://pi.cdfa.ca.gov/purpleloosestrife/BioControl.htm

http://www.ducks.ca/purple/

http://www.dnr.state.mn.us/ecological_services/exotics/plprog.html

http://www.miseagrant.org/pp/

http://www.hort.uconn.edu/ipm/ipmbio.htm

http://www.invasiveplants.net/InvasivePlants/PurpleLoosestrife/

PurpleLoosestrife.asp

http://www.inhs.uiuc.edu/cee/loosestrife/bcpl.html

http://www.forestryimages.org

http://www.bugwood.org

Biological Control Rearing

http://www.entomology.wisc.edu/mbcn/fea501.html

http://www.ianr.unl.edu/pubs/weeds/g1436.htm

http://mtwow.org/bio-control-purple-loosestrife-links.htm

http://www.dccl.org/information/Purple_Loosestrife/REARGUI2.doc

http://www.miseagrant.org/pp/

http://www.extension.umn.edu/distribution/horticulture/DG7080.html

http://www.hort.uconn.edu/ipm/ipmbio.htm

http://www.inhs.uiuc.edu/cee/loosestrife/bcpl.html
60 Selected References

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Research

http://www.entomology.wisc.edu/mbcn/fea501.html

http://www.ag.unr.edu/wsj/purpleloose.html

http://www.unce.unr.edu/publications/FS02/FS0258.pdf

http://www.ducks.ca/purple/abstracts/abstrct1.html

http://www.accesskansas.org/kda/Plantpest/PestManagement/plantpurpleloosestrife.htm

http://www.miseagrant.org/pp/

http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm

http://www.ceris.purdue.edu/napis/states/ct/ctpls/pls1999.html

Impact

http://www.entomology.wisc.edu/mbcn/fea501.html

http://www.conservation.state.mo.us/conmag/1998/08/5.html

http://asuwlink.uwyo.edu/~caps/purple/purplels.html

http://www.ag.unr.edu/wsj/purpleloose.html

http://www.unce.unr.edu/publications/FS02/FS0258.pdf

http://www.nwcb.wa.gov/weed_info/ploosestrife.html

http://dnr.metrokc.gov/wlr/pi/loosestf.htm

http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm

Education

http://www.lakeheadca.com/lsstrife.htm

http://www.dnr.state.wi.us/org/caer/ce/eek/veg/plants/purpleloosestrife.htm

http://paipm.cas.psu.edu/Ploosestrife.htm

http://members.efn.org/~ipmpa/Noxploos.html

http://www.four-h.purdue.edu/download/purple/pdf/pl_promo.pdf

http://www.miseagrant.org/pp/
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

GLOSSARY 61

GLOSSARY

alternate Leaves that are arranged singly along a stem; one leaf

or bud at each node on alternate sides of the stem.

aerenchyma A spongy tissue with large air spaces found between the

cells of the stems and leaves of aquatic plants, providing

buoyancy and allowing the circulation of gases.

aspirator An apparatus used to suck insects into a collection

container. The device can be simple (as in a mouthaspirator) or mechanical (as in a gasoline- or batterypowered vacuum aspirator).

basal At the base of a plant or plant part.

biological control The intentional use of a weed’s natural enemy for

control purposes; also referred to as biocontrol.

bolting Plant stage at which the flower stalk begins to grow.

capsule A pod or seed vessel made of two or more cells, which

becomes dry and splits open when mature to release its

seeds.

cuticle The wax layer lining the epidermis of plant leaves,

preventing dehydration.

density Number of individuals per unit area.

diapause Period of dormancy in insects.

duff Partially decayed organic matter on the forest floor.

elytron (pl. elytra) Hardened forewing of a beetle.

epidermis The outer layer of cells of plant tissue.
62 Glossary

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

emergence Act of adult insect leaving the pupal case or re-appearing after overwintering.

exoskeleton Hard, outer frame of an insect that provides structure.

frass Plant fragments, usually mixed with excrement, deposited by feeding insects.

host specificity The dietary restriction of an organism to a single or

limited food (for herbivores: the number of plant species

accepted as food), highly-evolved, often obligatory

association between an insect and its host(s).

inflorescence The flowering structure of a plant.

instar The period or stage between molts in a insect larva.

larva (pl. larvae) Immature insect stage between the egg and pupa.

leaf beetles Small leaf-eating beetles.

membranous Thin and transparent.

metamorphosis The change from one life stage to another in insects,

such as from larva to pupa.

molt The process of shedding the exoskeleton in insects

during metamorphosis.

monoculture An area vegetated by a single plant species.

nocturnal To be active at night time.

node Points on a stem from which leaves, shoots, or flowers

grow—also known as a “joint.”

organdy A fine, transparent cloth or fabric.

oviposit To lay or deposit eggs.

perennial A plant living more than two years.

phenology Chronological sequence (influenced by climate) of an

organism’s life cycle.

photosynthetic tissue The production of carbohydrates in plant cells from

carbon dioxide and water in the presence of light

energy.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

GLOSSARY 63

pubescence The short, fine hairs covering a leaf, stem, or flower.

pupa (pl. pupae) (v. pupate) Nonfeeding, inactive stage between larva and adult in

insects.

quadrat A specific area used to sample vegetation (e.g.,1 square

meter).

qualitative Measurement of descriptive elements (e.g., age class,

distribution).

quantitative Measurement of number or amount (e.g., number of

seeds per capsule).

senescence Decline and death of an organism due to age.

snout The prolongation of the head of a weevil.

synchrony Occurring at the same time.

thorax Body region of an insect behind the head bearing the

legs and wings.

transect A straight line or path through an area.

variable A quantity that has any one of a set of values, i.e., plant

height.

vegetative reproduction Reproduction in plants other than by seeds, such as

from rhizomes, stolons, and from nodes on roots.

viability The proportion of seeds propagules (for example seeds)

that are alive.

weevil A type of plant eating beetle, the adults having distinct

snouts of variable lengths.
64 Acknowledgements

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

ACKNOWLEDGMENTS

We thank Gary Piper (Washington State University), Eric Coombs (Oregon Department of Agriculture), Douglas Landis (Michigan State University), and Robert

Wiedenmann (University of Illinois/Illinois Natural History Survey) for their contributions to this manual. Thanks also to Mark Riffe of INTECS/Forest Health Technology Enterprise Team, USDA Forest Service, Fort Collins, CO, for editing, layout,

and graphics. We also thank J. Johnson and M. Moses for reviewing this manual; and

Richard Reardon of the Forest Health Technology Enterprise Team, USDA Forest

Service, Morgantown, West Virginia, for providing the funds needed to prepare and

publish this manual.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

SOURCES OF FIGURES 65

SOURCES OF FIGURES

Cover E. Coombs, Oregon Department of Agriculture (purple

loosestrife), S. Schooler, Oregon State University

(purple loosestrife beetle), and M. Schwarzlaender,

University of Idaho (purple loosestrife root weevil)

Figure 1 B. Myers-Rice, The Nature Conservancy

Figures 2, 7, 12, 17, 22, 33 University of Idaho

Figures 3a, 9, 13 L. Wilson, University of Idaho

Figures 3b, 3c , 15, 16a, 19, G. Piper, Washington State University

 20, 21, 29

Figure 4 Adapted from Thompson et al. 1987 (http://

www.npwrc.usgs.gov/resource/1999/loosstrf/

loosstrf.htm )

Figures 5, 26 C. Randall, U.S. Forest Service

Figure 6 Adapted from Biological Control of Weeds in the West,

Rees et al. (1996)

Figure 8a M. Schwarzlaender, University of Idaho

Figure 8b Bioimages (http://www.bioimages.org.uk)

Figures 10, 35, 38, 39 D. Landis, Michigan State University

Figures 11, 14, 23a, 23d, B. Blossey, Cornell University

 23e, 37

Figures 16b, 18, 30, 34, 36 E. Coombs, Oregon Department of Agriculture

Figure 23 (drawing) C. Roché, Medford, Oregon

Figure 23b M. Schwarzlaender, University of Idaho

Figures 23c, 24 Agriculture and Agri-Food Canada Archives

Figures 25, 26 M. Moses, University of Idaho

Figures 27, 28 K. Loeffleman, University of Idaho
66 Sources of Figures

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Figures 31, 32 David Voegtlin, Illinois Natural History Survey

http://www.inhs.uiuc.edu/cee/loosestrife/mrear.html

Table 1

Lythrum alatum, L. lineare, L. hyssopifolia, and L. virgatum

Adapted from Illustrated Companion to Gleason

and Cronquist’s manual: Illustrations of the

Vascular Plants of Northeastern United States

and Adjacent Canada, Holmgren (1998)

L. flagellare New York Botanical Garden

(http://www.nybg.org/bsci/hcol/vasc/

Lythraceae.html)

L. curtissii Georgia Department of Natural Resources

(http://www.georgiawildlife.com/assets/documents/lythcu.pdf)

L. ovalifolium Adapted from Aquatic and Wetland Plants of

the Southwestern United States, Correll and

Correll (1995)

L. maritimum Adapted from Manual of the Flowering Plants

of Hawai’i, Wagner et al. (1999)

L. californicum, L. tribracteatum

Adapted from Intermountain Flora, Cronquist

et al. (1997)

Table 2

Spirea douglasii L. Wilson, University of Idaho

Epilobium angustifolium L. Wilson, University of Idaho

Verbena hastata Michigan Department of Natural Resources

(http://www.michigan.gov/dnr/0,1607,7-153-

10370_12146_12213-36285—,00.html)

Lythrum salicaria Eric Coombs, Oregon State University

Table 3 D. Landis, Michigan State University (Galerucella)

M. Schwarzlaender, University of Idaho (Hylobius)

Bioimages (http://www.bioimages.org.uk) (Nanophyes)

Photographs used in this publication can be accessed on line through reference codes (UGA0000000)

in the captions for the figures. Point your browser at http://www.forestryimages.org, and enter the

reference code at the search prompt.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 67

APPENDIX: TROUBLESHOOTING GUIDE AND FORMS

Troubleshooting Guide: When Things Go Wrong

Purple Loosestrife Biocontrol Release Form

Monitoring Plan Questionnaire

Form 1: Purple Loosestrife Biocontrol Monitoring – Site Location

Form 2: Purple Loosestrife Biocontrol Monitoring – Biocontrol

Agent Monitoring

Form 3: Purple Loosestrife Biocontrol Monitoring – Vegetation

Monitoring

Form 4: Purple Loosestrife Biocontrol Monitoring – Associated

Vegetation

Note: Please make photocopies of these appendices and use them as worksheets.

___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 69

Troubleshooting Guide: When Things Go Wrong

This guide is intended to assist those who encounter problems when establishing a biological control

program for purple loosestrife. It identifies the probable cause of common problems and offers solutions.

Problem Probable Cause Solution

Biocontrol agents unhealthy Physical damage to insects Prevent collection containers from colliding; use crushresistant containers. When aspirating, change vials often,

avoid long exposure and crowding in vials.

Drowning Do not put excess water in the collection containers but

keep the foam moist. Prevent accumulation of excess

moisture in the containers.

Excess or prolonged heat or

cold

Keep containers cool at all times; use coolers and ice

packs; avoid exposure to direct sunlight while in transit.

Starvation Put purple loosestrife stems with foliage (no flowers,

seeds, or roots) in container; minimize time insects are in

containers.

Release delay Transport or ship agents immediately after collection;

release agents at new site immediately upon arrival or

receipt of beetles.

Parasitism and/or disease Check source of agents when obtained from a supplier;

ensure insect population is disease-free when collecting

or receiving shipment.

Number of eggs low Agents past reproductive

stage

Collect adults at times of early peak activity (i.e., when

insects are abundant and mating).

Few beetles collected Wrong collection method

used

Refer to Table 4 for recommended collection time and

technique.

Collection done at wrong

time

Refer to Table 4 for recommended collection time and

technique.

Collection technique Beetles can be killed during sweeping or aspirating; use

vacuum aspirator if aspirating by mouth is not working;

practice aspirating and sweeping.

Conditions at time of

collection

Collect in suitable weather.

Biocontrol agents not found

after release

Site is unsuitable Refer to "Releasing Biocontrol Agents" section.

Site too small Select a larger site and dense stand of purple loosestrife.

Monitoring method Monitoring method is inappropriate or monitoring was

done at the wrong time.

Not enough agents released Repeat releases with a larger number; don't give up.

Bad luck Bad weather event, flooding, spraying, or other event

may have eradicated beetles. Initiate another release.
70 Appendix

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Problem Probable Cause Solution

Beetles do not build up

populations in years after

release

Existing populations may be

too small

Release additional beetles.

Predation Investigate and release large numbers to "swamp" site to

avoid specific predators.

Site unsuitable Don't give up: repeat steps outlined above or try to assess

which factors are critical and can be changed.

Cannot locate release site Permanent location marker

not found

Use bright-colored wooden, metal, or plastic stake;

locate site with GPS coordinates.

Map incorrectly or poorly

drawn

Check map, redraw with more detail, or add landmarks.
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 71

Purple Loosestrife Biocontrol Release Form

Released By: _____________________________ Release Date: ___/___/___ 

(mm dd yy)

County: ____________________State:________ # Released: _________ 

Biocontrol Agent: _________________________________ Date Collected: ___/___/___ 

 (mm dd yy)

Source of Agents: _________________________________ 

 

Life Stage (circle): Larvae Pupae Adults Eggs Other (specify) ___________________

Land Ownership (circle): Private County State USFS BLM COE BOR BIA/Tribe TNC Other (specify) _____________

Legal: T_____ R_____ Sec_____ Q_____ QQ_____ Lat: Deg____Min____Sec______ Long: Deg___Min_____Sec______ 

ENVIRONMENT

Temperature (°F):________ Wind: Calm Light Moderate Strong Gusty Wind Direction: N S E W 

Weather (circle): Clear Ptly Cloudy Cloudy Rain Release Time:_____________am/pm

Site Elevation:_________________________ 

Disturbance: (check all that apply, circle most prevalent) Cultivation ___ Fire ___ Flood ___ Grazing ___ 

 Roads ____ Recreation ____ 

Directions to Site (include a map to the site on the back of this form): 

________________________________________________________________________________________________ 

________________________________________________________________________________________________ 

SITE CHARACTERISTICS 

Site Name:_______________________ Size of Infestation (acres):____________ Weed Cover %:_____________________ 

Weed Height:__________ Weed Density (# per meter sq.):________ Dominant Plant:____________________________ 

Distribution of Weed: Isolated_____ Scattered_____ Sc-Patchy_____ Patchy_____ Continuous_____ Linear_____

Phenology: Seedling % _____ Rosette %____ Bolt %_____ Bud %_____ Flowering %_____ Seed %____ Dormant %_____

Vegetation Type (check): 

River/Stream bank 

Wetland 

Ditch/Canal 

Lakeshore 

Reservoir 

Wet Meadow 

Dry Meadow 

Other (specify): __________________ 

Comments (continue on reverse if necessary):
72 Appendix

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Monitoring Plan Questionnaire

The following is a list of questions to be answered and documented prior to collecting data. Use the

checklist as an outline for a montiroing plan.

What is the management objective of the biocontrol release site? 

 a) Establish a study site for long-term monitoring. 

 b) Establish nursery site to increase numbers of beetles for future collection and redistribution. 

 c) Create an open release site; no additional monitoring is intended. 

Notes: _______________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

What will be measured? 

 a) Biocontrol agent presence/absence. 

 b) Biocontrol damage to target weed. 

 c) Plant community structure or composition. 

Notes: _______________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

What equipment and supplies are needed? ___________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

What training is needed?_________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

What is the cost of monitoring? ___________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

_____________________________________________________________________________ 

What is the interval between monitoring? ___________________________________________ 
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 73

Form 1: Purple Loosestrife Biocontrol Monitoring–Site Location

Site Name:___________________________ State:______________GPS: N _______o __________’ 

Town: ______________________________ County: _____________ W _______o __________’ 

Date: _________ __________ __________ 

 year month day 

CONTACT PERSON: LEGAL LANDOWNER:

Name: __________________________________ Name:___________________________________ 

Address: ________________________________ Address: _________________________________ 

City:____________________________________ City: ____________________________________ 

State:___________________________________ State: ___________________________________ 

Phone: _____ - ______ - ___________ Phone: _____ - ______ - ___________ 

e-mail: __________________________________ e-mail:___________________________________ 

SITE CHARACTERISTICS: 

Habitat type: ___River ___Wetland ___Lake ___Meadow ___Irrigation Ditch ___Other 

 Site

 Site

Road Map to Site

Site and Vegetation Map

INSECT RELEASE HISTORY: 

Date 

(year-month-day) 

Species Number and Stage 

(egg/larvae/adult) 

Position of Release 

On Map (1,2,3,4...) 

 
74 Appendix

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Form 2: Purple Loosestrife Biocontrol Monitoring–Insect Monitoring

 INVESTIGATORS: 

SITE: ___________________________ STATE: ___________ Last name First name 

DATE: _________ _________ _______ GPS: N _____o ___________' __________________ _____________________ 

 year month day 

 W _____o ___________' __________________ _____________________ 

 __________________ _____________________ 

TIME: _______________________ 

TEMPERATURE: ______________ Chart A Chart B: 

 Insect Abundance (#/stem) Damage or Percent Cover Class 

WEATHER: ___________________ 

A <1% 

B 1-5% 

C 6-25% 

D 26-50% 

E 51-75% 

F 76-95% 

G >95% 

I 1-10 

II 11-25 

III 26-100 

IV 100-500 

V >500 1 = present 

2 = abundant 

3 = very abundant 

 A = Adults Hyl = Hylobius 

 L = Larvae Nano = Nanophyes 

 E= Eggs 

Quad Galerucella Hyl Nano Purple Loosestrife Cattail Other Insects seen: 

# A L E A A %damage %cover #stems %cover #stems 

1 

 

 

2 

 

 

3 

 

 

4 

 

 

5 

 

 

6 

 

 

7 

 

 

8 

 

 

9 

 

 

10 

 

Notes: 
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 75

Instructions for FORM 2: Purple Loosestrife Biocontrol Monitoring – Insect Monitoring 

Materials needed: 1.0 m2 quadrat frame, data sheets, stopwatch, pencils, clipboard. 

General: The purpose of this activity is to estimate the abundance of biocontrol insects at the site. Conduct the 

monitoring in late spring/early summer, about a month after Galerucella adults appear after overwintering at your 

site. Monitoring is easier with two people, one to make the observations and the other to record data. 

1) Site information: Fill out the site information at the top of the form. 

2) Position the quadrat: Carefully approach the quadrat and watch for adults of all three species when you slide 

the quadrat frame into position. Hylobius and Nanophyes adults often drop from the vegetation once you touch 

stems (or even as you approach the quadrat). 

3) Beetle counting: Use a 1 minute total search time for each insect species released and for each life stage that 

can be observed. At a site where only Galerucella was released, 3 minutes total will be spent searching for eggs, 

larvae, and adults (one minute for eggs, one for larvae, and one for adults). At a site where only Hylobius or 

Nanophyes were released, count only the adults for one minute. At sites with two or three species, count each 

species separately. Use Chart A to record the category of abundance (I-V). 

4) Estimate feeding damage: Examine the purple loosestrife for any damage to the leaves or shoots, such as the 

‘shothole’ feeding pattern of the Galerucella beetles. Estimate the percent leaf area removed by insect feeding over 

the entire quadrat, using Chart B to determine the category (A-G) of damage. Practice estimating the amount of 

leaf damage with an experienced observer. Initially after release, the amount of leaf damage will be low or nonexistent. As Galerucella density increases, so to will the amount of leaf damage, which can be very high (> 50%) 

at high beetle density. 

5) Measuring vegetation: After you have completed the insect counts, stand over the quadrat and visually 

estimate how much of the quadrat is covered by purple loosestrife and how much is covered by cattail (use cover 

estimates in Chart B). Cattail (Typha sp.) is the most common plant associated with wetlands across North 

America. If you do not have cattail, leave this category blank or substitute with the most common species at your 

site. Then, count the number of purple loosestrife (> 20 cm tall) and cattail stems. Be careful to distinguish 

between a stem and a branch; only stems are counted. 

6) Other observations: Record any general observations or useful information; disturbances, flooding, fire, bird 

nests, etc., for the sample quadrat or the site in general. 
76 Appendix

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Form 3: Purple Loosestrife Biocontrol Monitoring–Vegetation Monitoring

SITE: ________________________ STATE: ___________ Chart A: Percent Cover 

DATE: ________ _______ ______ GPS: N _____o__________' 

 year month day W _____o__________' 

INVESTIGATORS: 

Last name First name TIME:____________________ 

__________________ _________________ TEMPERATURE: __________ 

__________________ _________________ WEATHER: _______________ 

__________________ _________________ 

PL = Purple Loosestrife 

 Percent Cover Number Number of Purple Loosestrife (5 tallest stems) Cattail 

Quad (Chart B) of stems inflorescences (5 tallest stems) 

# PL Cattail PL Cattail PL Cattail Height (cm) 

# of 

inflorescences 

Length (cm) 

terminal 

inflorescence 

# Flower buds 

center 5cm of 

inflorescence Height 

(cm) S/F 

1 

 

 

2 

 

3 

 

4 

 

5 

 

6 

 

7 

 

8 

 

9 

 

10 

 

A <1% 

B 1-5% 

C 6-25% 

D 26-50% 

E 51-75% 

F 76-95% 

G >95% 

S= sterile 

F = fertile 
___________________________________________ BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE

APPENDIX 77

Instructions for Form 3 - Purple Loosestrife Biocontrol Monitoring – Vegetation Monitoring 

Materials needed: 1 meter stick, 1.0 m2 quadrat frame, data sheets, pencils, clipboard, camera, and GPS unit to 

relocate quadrats. The site visit should be from late August to early October. 

General: The purpose of this activity is to estimate the abundance of purple loosestrife and other vegetation in the 

wetland community, and to record measurements of purple loosestrife plant attributes. Conduct monitoring in late 

summer to mid autumn. Monitoring is easier with two people, one to make the observations and the other to record 

data. 

1) Site information: Fill out the site information at the top of the form. 

2) Position the quadrat: Carefully position the quadrat on the ground in the purple loosestrife infestation, being 

sure not to damage the plants, i.e., break stems, etc. 

3) Estimate percent cover: Slide the quadrat frame into position, as close to the ground as possible; move stems 

in or out of the frame so that all stems originating in the quadrat are included. Standing near the frame, estimate 

how much of the quadrat is covered by purple loosestrife and, independently, how much is covered by cattail. Use 

cover estimates in Chart A to estimate percent cover. 

4) Count stems: Count the number of loosestrife and cattail stems, beginning at one corner of the quadrat and 

working systematically across the quadrat. To be counted, a stem must be >20cm tall and originate within the 

quadrat; if it originates under the frame, or outside the frame and leans over the quadrat, then it is not recorded. Be 

careful to distinguish between a stem and a branch; only stems are counted. A stem originates from the ground or 

within 5 cm of the ground, while a branch originates from a stem at least 5 cm above the ground. In dense stands, it 

is helpful to look beneath the loosestrife canopy, and to move stems with your hands while counting; this is the 

easiest way to separate stems from branches. 

5) Count inflorescences: Next, count the total number of purple loosestrife and cattail inflorescences in your 

quadrat. Make sure to count only those inflorescences that originate on stems rooted in your quadrat. An 

inflorescence is the portion of stem above and including the lowest flower bud. Even if only one flower bud is 

present, it is counted as an inflorescence. Be careful to only count flower buds, and not the small bundles of reddish 

leaves in the inflorescence axils. 

6) Measure plants: Select the 5 tallest purple loosestrife stems in each quadrat (if there are fewer than 5 

stems/quadrat, measure all that are present); four measures will be made on each stem; a) Measure the stem height 

(to the closest cm); b) Count the number of inflorescences on that stem (including all side branches), c) Measure the 

length (to the closest cm) of the longest inflorescence on this stem (this will generally be the terminal 

inflorescence); d) Remove the central 5cm portion of this inflorescence. Count the number of flower buds in this 5 

cm length of inflorescence. If the plant did not produce any inflorescences or if they are shorter than 5 cm please 

record this in the appropriate form. Repeat this process for the remaining 4 loosestrife stems. Repeat with 5 tallest 

cattail stems. 

7) Other observations: Record any general observations or useful information, such as disturbances, flooding, fire, 

bird nests, etc. 
78 Appendix

BIOLOGY AND BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE ___________________________________________

Form 4: Purple Loosestrife Biocontrol Monitoring–Associated Vegetation

SITE: ____________________________ STATE: ______________________ Chart A: PercentCover 

DATE: ______ _______ _______ GPS: N _________o

___________ A <1% 

 year month day W _________o

___________ B 1-5% 

INVESTIGATORS: C 6-25% 

Last name First name TIME:____________________ D 26-50% 

 TEMPERATURE: __________ E 51-75% 

WEATHER: _______________ F 76-95% 

 G >95% 

 

Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 

Percent of Quadrat (Use Chart B or actual estimates that total 100%) 

 Vegetated 

 Unvegetated (soil, water, litter, etc) 

 

Vegetation Cover (Use Chart B; total may exceed 100% due to overlapping of vegetation) 

 Purple Loosestrife 

 Cattail 

 All other vegetation: 

 Forbs 

 Grasses and Sedges 

 Woody plants 

 

Individual Species (names) (Check if present or use Chart B to indicate percent cover)