United States Department of Agriculture 

FIELD GUIDE TO DISEASES AND INSECTS OF 

QUAKING ASPEN IN THE WEST 

Part I: WOOD AND BARK BORING INSECTS 

Brytten E. Steed and David A. Burton 

Forest Forest Health Protection Publication April 


Service Northern Region R1-15-07 2015
 
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WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS 

CITATION 

Steed, Brytten E.; Burton, David A. 2015. Field guide to diseases and insects 

of quaking aspen in the West - Part I: wood and bark boring insects. U.S. 


Department of Agriculture, Forest Service, Forest Health Protection, Missoula 

MT. 115 pp.
 

FIELD GUIDE TO

DISEASES AND INSECTS OF 


QUAKING ASPEN IN THE WEST 

AUTHORS 

Brytten E. Steed, PhD Part I: WOOD AND BARK 


Forest Entomologist
 BORING INSECTS USFS Forest Health Protection 

Missoula, MT Brytten E. Steed and David A. Burton 

David A. Burton 

Project Director 

Aspen Delineation Project 

Penryn, CA 

ACKNOWLEDGEMENTS 

Technical review, including species clarifications, were provided in part by Ian 


Foley, Mike Ivie, Jim LaBonte and Richard Worth.
 

Additional reviews and comments were received from Bill Ciesla, Gregg 


DeNitto, Tom Eckberg, Ken Gibson, Carl Jorgensen, Jim Steed and Dan Miller. 


Many other colleagues gave us feedback along the way - Thank you!
 

Special thanks to Betsy Graham whose friendship and phenomenal talents in 


graphics design made this production possible.
 

Cover images (from top left clockwise): poplar borer (T. Zegler), poplar flathead (T. Zegler), aspen bark beetle (B. Steed), and galls from an unidentified 


agent (B. Steed). We thank the many contributors of photographs accessed 


through Bugwood, BugGuide and Moth Photographers (specific recognition in 
 United States Department of Agriculture Figure Credits). Forest Service 

Forest Health Protection 

photo by B. Steed 
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WOOD & BARK BORING INSECTS 

Table of Contents Page 

INTRODUCTION 6 

Table 3: Host and range details of principle wood and bark boring insects 12 

INDIVIDUAL AGENT DESCRIPTIONS 

Scientific name: 

root, root crown, lower stem 

Lepidoptera (moths, butterflies) 

Sesia tibialis 

Sesia apiformis
 

Sthenopis purpurascens
 

Coleoptera (beetles) 

Agrilus horni 

Xylotrechus obliteratus 

Xylotrechus mormonus 

Xylotrechus annosus 

Hymenoptera (ants, bees, wasps) 

Camponotus spp. 

trunk and larger branches 

Lepidoptera (moths, butterflies) 

Acossus centerensis
 

Acossus populi
 

Prionoxystus robiniae
 

Coleoptera (beetles) 

Agrilus granulatus liragus 

Buprestis confluenta 

Buprestis viridisuturalis 

Chrysobothris femorata 

Chrysobothris mali 

Cryptorhynchus lapathi 

Dicerca callosa 

Dicerca tenebrica 

Poecilonota californica 

Poecilonota cyanipes 

Poecilonota ferrea 

Saperda calcarata 

Common names:

American hornet moth, 20 

cottonwood crown borer 

hornet moth 

four spotted ghost moth, 23 

poplar ghost moth 

aspen root girdler 25 

poplar-butt borer 27 

poplar butt borer 

(a longhorned woodborer) 

carpenter ant 30

poplar carpenterworm, 33 

aspen carpenterworm 35 

carpenterworm, goat moth 37 

bronze poplar borer 41 

gold dust buprestid; 45 

yellow spotted jewel beetle 

(a flatheaded woodborer, jewel beetle) 

flatheaded appletree borer 47 

Pacific flatheaded borer 50 

poplar-and-willow borer 52 

(a flatheaded woodborer) 55 

flatheaded poplar borer 57 

western poplar buprestid 59 

eastern poplar buprestid, 61 

bluefooted poplar buprestid 

iron flathead 64 

poplar borer, aspen borer 66 

WOOD & BARK BORING INSECTS
 

Scientific name: 

small branches and twigs 

Lepidoptera (moths, butterflies) 

Paranthrene tabaniformis 

Paranthrene dolli 

Paranthrene robiniae 

Coleoptera (beetles) 

Oberea schaumii
 

Oberea delongi
 

Oberea quadricallosa
 

Saperda inornata 

Saperda populnea 

Diptera (flies, midges) 

Hexomyza schineri 

Hymenoptera (sawflies, wasps, ants) 

Janus abbreviatus 

Common names:

dusky clearwing, 

poplar twig clearwing 

cottonwood clearwing 

western poplar clearwing 

70 

poplar branch borer 

poplar twig borer 

(a longhorned woodborer) 

poplar gall saperda 

small poplar borer 

74 

77 

80 

poplar twiggall fly 83 

willow shoot sawfly 86

 bark beetles and other bark insects - trunk or branches 

Coleoptera (beetles) 

Procryphalus mucronatus
 

Trypophloeus populi
 

Trypophloeus thatcheri
 

Trypodendron retusum
 

Ptilinus basalis
 

Anobiidae
 

OTHER: bark mining insects
 

Lepidoptera (moths, butterflies)
 

Cydia populana
 

Marmara spp.
 

Diptera (flies, midges)
 

Phytobia spp.
 

INDEX – AGENT SCIENTIFIC NAME 

INDEX – AGENT COMMON NAMES 

TREE COMMON AND SCIENTIFIC NAMES 

REFERENCES 

FIGURE CREDITS 

DEDICATION 

(an aspen bark beetle) 89 

(an aspen bark beetle) 91 

(an aspen bark beetle) 

poplar ambrosia beetle 94 

(a powder-post beetle) 

(death watch beetle) 

96 

(a bark moth) 

(a bark moth) 

(a bark fly) 

100 

103 

104 

105 

111 

115 
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WOOD & BARK BORING INSECTS
 

INTRODUCTION TO 

WOOD & BARK BORING 

INSECTS OF ASPEN 

THE TREE 

Quaking aspen (Populus tremuloides Michx) is the most widely distributed tree species in North America. Additional common names include 

trembling aspen, golden aspen, mountain aspen, popple, poplar, trembling poplar, and in Spanish, álamo blanco and álamo temblón. 

Quaking aspen occurs across Canada in all provinces and territories, 

including Nunavut (Akimiski Island). In the United States, it can be 

found as far north as the southern slopes of the Brooks Range in Alaska, 

and as far south as Arizona and New Mexico (Fig. 1). In the western 

United States, this tree is generally found at 5,000–12,000 feet (1,500– 

3,700 m), rarely below 1,500 feet (460 m). It also grows in isolated 

patches as far south as Guanajuato, Mexico. 

WOOD & BARK BORING INSECTS
 

Other Populus species native to North America include bigtooth aspen 

(P. grandidentata Michaux) and several cottonwood and poplar species 

(see Index – plant common and scientific names for partial listing). 

Although some damage agents are specific to quaking aspen, many use 

numerous Populus species. Some agents also include on their menu trees 

and shrubs in the closely related Salix (willow) genera, and others feed 

on a wide range of hardwood trees and shrubs. This guide focuses on 

agents damaging to quaking aspen, although other hosts are noted. 

The various parts of a tree serve different functions in feeding, protecting, and stabilizing a tree. Damage to a tree that compromises these 

functions can result in reduced tree vigor (fewer defenses and ability 

to grow) or when severe or in concert with other agents, in tree death. 

Figure 1. Current range of quaking aspen (green) in North America (E. L. Little, Jr. [1971]) Figure 2. Locations on and within an aspen where damage may occur 
9 

WOOD & BARK BORING INSECTS 

Location of damage may be described using terms found in Figure 

2, including where on a tree damage is most likely to occur and the 

anatomy most likely affected. 

Distribution of individual insect damage agents are described using 

zones. In Canada, three zones are used: west, east and north. In the 

U.S. three zones are used: west, east, south. Alaska is lumped with the 

Canadian north zone (Fig. 3). These divisions are based on past geopolitical convention and genetics of aspen. The U.S. “south” zone is not 

within aspen’s native range although some agents may be present within 

these areas on other host tree species. 

Figure 3. Zones used in Canada and U.S. for descriptions of agent distribution 

WOOD & BARK BORING INSECTS
 

A key to the codes used throughout the text for U.S. states and Canadian provinces is given in Table 1. 

Table 1. Abbreviations of States and Provinces 

THE INSECTS 

Wood and bark boring insects come from several orders. Typically the 

larval stage of these insects cause most damage and are the longest-lived. 

Being able to differentiate taxonomic groups of borers based on basic 

larval traits can be helpful in identifying the damage agent. Table 2 illustrates and describes larval forms of insects included in this guide. 

Table 3 lists wood and bark boring insects that have been found damaging quaking aspen in western U.S. and Canada. Many of these may be 

found in other parts of quaking aspen’s range. A comparison of important characteristics of these agents is provided although information on 

some species is limited. 

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WOOD & BARK BORING INSECTS NOTES 

Table 2. Adult and larval forms of wood boring insects covered in this guide 
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WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS 

Table 3. Host and range details of principal wood and bark boring insects 
14 15 

WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS
 
16 17 

WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS
 
WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS
 

INDIVIDUAL 

AGENT 

DESCRIPTIONS 

photo by H. Kearns 

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WOOD & BARK BORING INSECTS
 

AMERICAN HORNET MOTH 

(COTTONWOOD CROWN BORER) 

Sesia tibials (Harris) Lepidoptera: Sesiidae 

[=Sesia tibiale (Harris); =Aegeria tibialis pacifica (Hy. Edwards)] 

Distribution: Widespread from North Atlantic coast, through northern U.S. 

and southern Canada, south into the Rocky Mountains (to AZ) and west to the 

Pacific Coast (CA) 

Hosts: Cottonwoods (including eastern, white, Fremont and black) and poplars 

(including balsam and white) common; willows and aspen occasional 

Identification: Adults are about 25 mm long and look very much like yellowjacket wasps. They are black with bright yellow stripes and accents, and long legs. 

Wings are 30-40 mm long, transparent, and without scales except for along veins 

and fringes which are lined with brown 

scales. Female antennae are wider 

toward head but pointed at tip; male 

antennae have comb-like projections 

on each segment (unipectinate). Head 

is black on top and front with yellow 

on either side. Abdominal segments 

1, 2, 4 are usually brownish black, 

and segments 3 and 5-7 yellow with 

brown-black on back (posterior) 

margins. Larvae have off-white 

bodies, red-brown to black heads, tan 

thoracic shields, and grow to 40 mm. 

Abdominal legs (prolegs) are very short 

with small, poorly developed hooks at 

the ends (crochets). Eggs are oval and light to medium brown, with a net-like 

patterned surface. Pupae are brown and about 5 cm long and 12 mm wide. 

Life History: Adults emerge from infested trees in late spring through early 

summer by boring a 6 mm hole near the tree’s base. Adults only live 4-10 days 

during which females deposit 200-600 eggs in cracks and crevices of bark around 

base of host tree. After three weeks eggs hatch and 1.3 mm-long larvae crawl 

down to soil line to bore into root collar of tree. Larvae initially feed in tunnels 

in cambial area, later developing galleries into sapwood. When larvae mature 

they form cocoons from wood chips and pupate. Larvae overwinter twice in 

their 2-year life cycle, emerging their 3rd summer. Larvae in basal stem tunnel to 

edge of bark to pupate; larvae in roots often enter the soil, construct a silk-lined 

Figure 1. Adult American hornet moth 

WOOD & BARK BORING INSECTS
 

Key:

• Holes at base of tree, ~ 6 mm in diameter, often with pupal case protruding half-way out 

• Larvae tunnel in cambium and sapwood of trees, above or at soil line, in lower trunk, root crown, or exposed 

roots 

• Larvae with very short prolegs, tipped with a series of small, poorly developed hooks 

• Adult moth that looks wasp-like: yellow and black stripes, and transparent wings 

pupal chamber out of excavated wood 

chips, and finally wriggle to the surface 

before emerging as adults. 

Damage: Larvae feed at or below soil 

line (e.g. lower trunk, root crown, and 

roots), mostly in the cambial layer, 

occasionally boring into solid wood. 

Oozing sap and fine frass/boring 

dust at base of tree are indicators of 

infestation. Larval tunnels, varying in 

shape and mostly free of frass/boring 

dust, are about 9 mm diameter and 

7-12 cm long. Upon emerging, adults 

leave pupal cases partially protruding from ~6mm wide exit holes. Trees of all 

sizes are infested, with an apparent preference for stressed or damaged trees. 

Tunneling structurally weakens trees, increasing their susceptibility to wind 

and snow breakage—especially if repeatedly attacked. Small trees can be killed 

outright by girdling. Holes also provide entry for disease agents. 

Similar Damage: Clearwing moths, a common name for the Sessidae family of 

moths, are easily confused with other insects. Adults resemble wasps and hornets, 

and larvae resemble a number of other pests. Larvae cannot be separated easily 

from those of other 

aspen-boring moths 

of similar size such as 

aspen carpenterworm 

(Acossus populi), 

poplar carpenterworm 

(A. centerensis), four 


spotted ghost moth 


(Sthenopis purpurascens
 

and carpenterworm 


(Prionoxystus robiniae), 


although full grown 


larvae of four spotted 


Figure 2. American hornet moth larvae 

Figure 3. American hornet moth pupae in chip cocoon 

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WOOD & BARK BORING INSECTS 

ghost moth and carpenterworm tend 

to be larger in size. Of the moth borer, 

only the larger four spotted ghost moth 

also attacks stems at or below soil line. 

Wood borer beetle larvae that attack at 

or below soil line such as poplar-butt 

borer (Xylotrechus obliterates) and aspen 

root girdler (Agrilus horni) are smaller 

in size and do not have legs or prolegs. 

A second clearwing moth, the 

(European) hornet moth (Sesia 

apiformes [Clerck]) was introduced 

into North America in the mid1800’s, also attacks Populus species 

(although aspen is not listed as a host), 

and looks very similar to S. tibialis. Its 

distribution overlaps in northeast U.S. and NL, but overlap in other areas is 

unclear due to confusion in identification with native species. However, it is 

reportedly established in CA. It is possible that S. apiformis tunnels are longer, 

reported to be 20-50 cm versus 7-12 cm for S. tibialis. Body segment color on 

adults differ by species, and larvae of S. tibialis have a distinctly more wrinkled 

head surface. 

Remarks: 

• Nursery stocks of poplar species often attacked 

• Day-flying moths rarely seen except if pheromone-baited traps are used 

References: 1, 10, 12, 13, 18, 20, 26, 28, 37, 55, 56, 58, 75, 91, 95, 98 

Figure 4. American hornet moth pair 

WOOD & BARK BORING INSECTS
 

FOUR SPOTTED GHOST MOTH 

(POPLAR GHOST MOTH) 

Sthenopis purpurascens (Packard) Lepidoptera: Hepialidae 

[=Sthenopis quadriguttatus (Grote)] 

Distribution: NL and NY north and west to BC and NT, possibly south in 

mountains to AZ; common in AB in boreal forest and aspen parklands – less 

common in foothills and mountains or along wooded parts of grassland 

Hosts: Populus species: when described as two species, quaking aspen and willow 

considered primary hosts for S. quadriguttatus; alder and perhaps balsam poplar 

for S. purpurascens 

Identification: Adults are large moths (66-100 mm wingspan; perhaps as small 

as 35 mm) with two color forms; purple-gray and yellow-brown. Previously, 

the yellow-brown form (with quaking aspen as a preferred host) was considered 

a separate species – S. quadriguttatus (Grote). Forewings have two small silver 

spots near base, dark band running obliquely through mid-wing front to back, 

and darker wing ends. Hindwings are solid purple-brown or salmon-pink, 

depending on color form, with two spots along front edge. Antennae of both 

males and females are thread-like, unlike most large northern moths. Eggs are 

round, smooth and unornamented. Mature larvae are cream white, (35 to) 50 

to 60 mm long with reddish brown heads and prothoracic shields, and brown 

at bases of setae (hairs); abdominal segments 3-7 have wart-like protuberances 

(dorsal pinaclule). Pupae are slender and brown. 

Life History: Adults fly mid- to latesummer, often peaking in July, and seen 

most just after dawn or dusk (crepuscular). 

Females with eggs may be too heavy to 

fly well until complement of eggs are laid. 

Otherwise, flight is described as swift 

and close to ground. Eggs are deposited 

indiscriminately in vicinity of host trees. 

Larvae bore into roots of aspen or, to a 

lesser extent, into other hosts. In late spring 

larvae pupate within galleries. It is likely 

that pupae wriggle up their gallery to soil 

line when adults are ready to emerge. Life 

cycle is 1-2 years. 

Figure 1. Adult four spotted ghost moth 

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WOOD & BARK BORING INSECTS
 

Key:

• Frass and wood chips on ground at base of host trees; some perhaps as loosely woven 1-2 cm balls 

• Tunnels into soil around root system of host trees 

• Large moth with patterned forewing and mostly solid-colored hind wing ranging in color from salmon-pink to 

purple-brown; swift flying and crepuscular. 

Damage: Attacks occur at ground line 

or below, often making infestation 

difficult to identify. Larvae excavate 

extensively at root collar and in large 

roots; galleries are typically 10-15 cm 

long and 10-12 mm wide but multiple 

chambers within galleries may be 25­

30 mm in diameter. In smaller roots 

galleries are usually narrower but may 

be up to 70 cm long. Frass and woodchips from root excavation are loosely bound with fine webbing into 1-2 cm 

diameter clumps and ejected from galleries. Gallery entrances may be loosely 

plugged but are usually open. Similar species also have silk-lined galleries 

extending up through soil. Root feeding can create entry points for numerous 

pathogens and can result in high levels of rot fungi that further damage root 

systems and exacerbate loss of structural integrity. 

Similar Damage: Hornet moths (Sesia species), aspen root girdler (Agrilus 

horni), and poplar-butt borer (Xylotrechus obliteratus) also bore at tree base, root 

collar, or upper roots. However, mature larvae of four spotted ghost moth are 

larger than hornet moth larvae, and differ in shape from that of the wood boring 

beetles aspen root girdler and poplar-butt borer. Borers not listed may use lower 

portions of host trees but will likely have additional attacks further up trunk. 

Adult moths are very similar to S. argenteomaculatus (silver spotted ghost moth, 

also called alder root borer moth) which feeds on alder roots largely in northeast 

U.S. and into Canada. 

Remarks: 

•	 Ghost moths are not considered of particular management importance 

•	 Adults are poorly attracted to light although specimens have been obtained 

this way 

References: 31, 37, 55, 56, 59, 81, 91, 98 

Figure 2. Adult ghost moth with wings spread 

WOOD & BARK BORING INSECTS
 

ASPEN ROOT GIRDLER 

Agrilus horni Kerremans Coleoptera: Buprestidae 

[=Agrilus blanchardi Horn] 

Distribution: Found in Northeast (MA, NY), Midwest (WI, MI, SD, IA), 

Southwest (AZ), and east and central Canada (southern ON 

and MB) 

Hosts: Quaking aspen principal host but also uses bigtooth 

aspen, balsam poplar, and some aspen hybrids 

Identification: Adult aspen root girdlers are narrow, black 

beetles with green-to-copper iridescence and are 6.5-11.5 

mm long. Females are somewhat larger than males. Eggs 

are creamy-white, flattened ovals, 1.2 mm long and 0.8 mm 

wide. Egg membranes darken as embryos develop. Mature 

larvae are typical flathead borers, 25 mm long, white except Figure 1. Adult aspen for black mandibles and brownish pincher-like projections at root girdler tail end (anal forceps). Pupae are creamy-white and darken 

with age. 

Life History: Adults, present in May and June, feed on foliage for about 3 

weeks before females begin egg laying. Eggs are laid singly or in small groups 

at base of aspen suckers, within 3 cm of the ground. Natural egg mortality is 

high; eggs that survive hatch after 2 weeks. Larvae tunnel through the bark of 

these lower stems, then straight down into the large 

lateral roots. These straight galleries may become 

20-50 cm long. Larvae then move to cambium, and 

begin tunneling in tight spirals around roots back 

up to main stem. Spiraling tunnels, flattened and 

frass-filled, continue until they are 5-25 cm above 

ground. Larvae bore to stem’s center, carve out 

pupal chambers with exit holes, then overwinter in 

chambers. At the completion of pupation, adults 

emerge through D-shaped exit holes that will 

produce oval bark scars if stem has not been killed. 

Life cycle is likely 2 years. 

Damage: Aspen root borers tend to infest roots 

and stems of healthy aspen suckers less than 18 

cm diameter, although attacks are most common 

Figure 2. Bark swellings are often 

visible over aspen root girdler galleries 

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WOOD & BARK BORING INSECTS
 

Key: 

• Dying and dead girdled sprouts, usually 18 cm or less in diameter, sometimes maintaining dead leaves in 

winter after death 

• Spiral swellings around the base of shoots with frass-packed galleries found just under bark 

• Enlarged pupal chamber in stem, visible when stem is split open 

• D-shaped emergence holes or oval bark scars 

on stems less than 12 cm. Borers do not seem 


to prefer weakened suckers. Larvae girdle main 


roots and lower stems of aspen suckers. As they 


do, spiral swellings around base of stems may 


reveal borers’ presence. Occasionally galleries 


also wander back and forth. Girdled suckers 


die before normal leaf abscission and in winter 


suckers with dead leaves still attached will be 


visible. Stands with high numbers of sprouts 


are not greatly affected by root girdlers; but 


clones with sparse regeneration may suffer 


disproportionately more damage. 


Similar Damage: Beetles and larvae of aspen 

root girdler look very similar to bronze poplar 

borer (Agrilus granulatus liragus) and bronze 

birch borer (A. anxius Gory) but can be 

distinguished by their presence in sucker stems and roots rather than main 

stems of aspen or birch. Aspen root girdler’s sinuate galleries on larger stems 

may resemble bronze poplar borer but are generally located lower on stem near 

base. Poplar-and-willow borer also prefers stems less than 12 cm diameter but 

does not create spiral galleries or bore into roots; it also creates copious amounts 

of frass and is rarely found in aspen. Poplar-butt borer (Xylotrechus obliterates), 

cottonwood crown borer (Sesia tibialis), and four spotted ghost moth (Sthenopis 

purpurascens) also bore at tree bases, collar, and roots but leave round holes rather 

than D-shaped, and are larger in size. Aspen root girdler is a buprestid with 

larvae and adults that differ in shape from cerambycid or moth larvae and adults. 

Remarks: 

•	 Maintain healthy trees in dense stands to minimize damage 

•	 Cut and destroy infested trees; insecticide may be an option 

•	 Agrilus horni (Kerremans) has been proposed as a junior subjective synonym 

of A. acastus Kerremans 

References: 3, 13, 27, 37, 54, 55, 57, 68, 74, 75, 78, 91 

Figure 3. Spiral galleries of aspen root 

girdler with bark removed 

WOOD & BARK BORING INSECTS
 

POPLAR-BUTT BORER 

Xylotrechus obliteratus LeConte	 Coleoptera: Cerambycidae 

Distribution: Abundant in Rocky Mountain (including Waterton Lakes park in 

Canada); also found in some parts of eastern U.S. 

Hosts: Quaking aspen primary host, but other aspens and Populus may also be 

attacked 

Identification: Adults are robust, elongate, longhorned beetles, 10-18 mm long 

and 3.5-5.0 mm wide. They have cinnamon brown to dark gray elytra covered 

with sparse white hairs and three, curved yellow bands; the first one oblique, 

middle one curved (sometimes running up the central margin), last one transverse. 

Yellow bands may also exit on front and back edges of pronotum. Antennae 

are relatively short, 

reaching just past front 

edge of elytra. Eggs 

are not described. 

Larvae are dull-white, 

moderately robust, and 

typical of roundheaded 

woodborers. They also 

have fine velvety hairs 

on pronotum and 

blister-like structures 

(ampullae) on abdominal segments. Pupae are not described but those of similar 

species are dull white, often with stiff, slender points on sides of the pronotum. 

Life History: Adults are present in late summer (July-Aug.). Females deposit 

eggs in bark crevices or exposed wood on lower part of trunk. Larvae produce 

tunnels in wood around tree’s base, mostly at or just below ground level. Larvae 

feed beneath bark the first season, then overwinter in galleries. In spring, larvae 

tunnel into wood, extending galleries downward so that most of their feeding 

occurs at or below ground surface. They continue feeding for several years. 

When mature, larvae tunnel upward towards outer bark where they create pupal 

chambers. New adults bore through bark to emerge. 

Damage: Poplar-butt borer is a serious pest of aspen in the Rocky Mountain 

regions, especially in higher altitudes where it may be more prevalent than poplar 

borer (Saperda calcarata). Larval tunnels can be found in lower portions of tree 

stems that are weakened, dying, or broken. Because of repeated poplar-butt 

Figure 1. Poplar-butt borer adult 

26 
28 29 

WOOD & BARK BORING INSECTS 

Key: 

•	 Tunnels in wood around base of tree 

•	 Wind broken trees 

•	 Larvae typical of roundheaded woodborers 

•	 Adult longhorned beetles with antennae only about half as long as body, dark gray to brown elytra with 

three, curved yellow bands, and sparse white hairs. 

borer attacks, base of tree can become honey-combed with tunnels, especially 

at or just below ground surface but may include upper roots. Tree structure is 

compromised so trees often break during wind or snow storms. Females tend to 

return to infested trees for oviposition so that trees are attacked repeatedly until 

they finally succumb. Outright mortality can be common. 

Similar Damage: Aspen root girdler (Agrilus horni), American hornet moths 

(Sesia tibialis), and four spotted ghost moth (Sthenopis purpurascens) also focus 

boring damage at tree base, root collar, or upper roots, and are commonly found 

in aspen. Larvae of this cerambycid beetle, however, differ in shape and size from 

that of the buprestid or moth borers. Poplar-butt borer adults are striking with 

bright yellow stripes on dark, hard wing covers (elytra). Other aspen boring 

insects may use lower portions of host trees but will likely focus attacks further 

up trunk. 

Xylotrechus annosus (Say) 

is less brightly striped 

with 3 wavy lines on the 

elytra. Its size is similar at 

10.5-15 mm in length, 

3-4.5 mm in width. 

Noted originally from 

black cottonwood, it has 

been found in other dead 

or dying Populus and 

willow species, although 

quaking aspen is not 

specifically noted. In Canada, it has been found in aspen-hardwood forests. 

Little is known about the biology of this beetle although it is likely saproxylic 

(found in dead or dying wood). Although it is listed as being found in eastern 

U.S. and eastern Canada, it has been trapped in many areas of the U.S. (WA, 

MI, NH) and Canada (BC, AB, MB, ON and QU). 

Xylotrechus mormonus (LeConte) (not to be confused with X. mormonus Hopping, 

now called X. bowditchi hoppingi Linsley found in spruce) is another species 

noted for attacking willow. However, it was found emerging from a Poplulus 

(likely quaking aspen) stump in MT. Little is known about this transcontinental 

Figure 2. Xylotrechus annosus adult 

WOOD & BARK BORING INSECTS
 

Figure 3. Xylotrechus mormonus damage in Populus stump 

species. Adults are 12-17 

mm long and 3.7-5.5mm 

wide, gray beetles covered 

with sparse, gray hairs 

(pubescence). Elytra are 

marked by 2 or 3 sets of 

narrow, yellowish, broken 

transverse lines or “dashes”. 

In Canada this species is also 

called the popular butt borer. 

Remarks: 

•	 Trees at high elevations 

in Rocky Mountain 

States susceptible to attack; extensive areas at elevations of 2,100 m (7,000 

ft) and above in UT and CO affected with as many as 90% of stems attacked 

each year 

•	 Direct control impractical, since stumps and roots of infested trees would 

have to be treated or removed 

References: 1, 37, 40, 41, 48, 52, 53, 55, 59, 60, 83, 91, 95 

Figure 4. Xylotrechus mormonus adult 
31 

 

 

WOOD & BARK BORING INSECTS
 

CARPENTER ANT 

Camponotus species

Distribution: Transcontinental 

Hosts: other hardwoods and conifers 

Identification: Carpenter ants 

most often seen are black to 

reddish- or yellowish-black adult 

workers. These adults vary in size 

within a colony and among species 

but are generally 3-16 mm long. 

Ants have bent (elbowed), clubbed 

antennae and a constricted 

waist. When wings are present, 

front wings are larger than hind. 

Queen ants are rarely seen and 

considerably larger. Worker ants 

in Camponotus have an evenly 

rounded (convex) back (thoracic 

 Hymenoptera: Formicidae 

Figure 1. Adult carpenter ant (Camponotus sp.) 

dorsum) when viewed from the side; other ants that may be confused with 

Camponotus have a notch or depression present. Egg, larval and pupal stages are 

found within excavated galleries and tend to be cream colored; larvae are legless. 

Life History: Carpenter 

ants start new colonies by 

swarming in mass flights 

of winged individuals, 

usually in spring to midsummer. After a female 

ant has successfully mated, 

she breaks off her wings 

and begins her search for 

a suitable site to colonize 

and begin laying eggs. Figure 2. Carpenter ant larvae When larvae hatch, the 

queen will feed them from energy reserves stored within her body. Ant larvae go 

through four developmental stages (instars) and then form a cocoon in which 

they pupate. Once new adults (workers) emerge from pupal cases, the queen 

will lay more eggs and the new workers will take over raising the brood. It can 

WOOD & BARK BORING INSECTS 

Key: 

• Black to reddish-black ants 3-16 mm long in frass-free, honey-combed chamber system 

• Piles of light colored “sawdust” at base of tree 

take 3 to 4 years before an ant colony 

can build large enough numbers to be 

readily noticed. Full colony size can 

range from a few hundred to tens of 

thousands depending on the maturity 

of the colony and ant species. 

Damage: Carpenter ants in a live tree 

can indicate presence of heart or butt 

rot. They can also use galleries of wood 

boring insects that have attacked lower 

trunks of large trees. In both cases, 

carpenter ant excavations can further 

weaken the tree’s structural integrity 

if sound wood is removed. Although 

carpenter ants prefer softened wood for 

initial excavations, they can move into 

more solid wood as gallery creation 

progresses. Infested trees are subject to Figure 3. Frass from carpenter ants excavating wood wind breakage and the wood is usually borer galleries useless for lumber or pulpwood. They 

do not, however, kill trees directly. 

Early indications of infestation are worker ants coming and going from openings 

at the surface of wood. Carpenter ants do not actually eat wood but they 

chew through it to 

construct chambers. 

Inside, the ant 

galleries follow the 

softer springwood 

with numerous 

connections through 

the harder/darkened 

summerwood. 

Active galleries are 

kept clean of debris 

by adults pushing 

small fragments of 

boring dust out of Figure 4. Mound of frass located below carpenter ant chamber opening 

30 
33 

 

WOOD & BARK BORING INSECTS 

the internal chambers; 


accumulation of such 


debris below holes is a 


good indication of an 


infestation. Gallery walls 


are smooth, with a sandpapered appearance. 


Similar damage: 

Excavation of wood 

can also be indicative 

of termites which 

superficially resemble 

ants and also live in 

large colonies. However, 

termites have straight antenna (not elbowed), do not have constricted waists, 

and their galleries are lined with moist soil (not clean). Some larger, wood 

boring insects that attack larger tree trunks will also produce frass and extensive 

galleries. If wood borer galleries are used by carpenter ants, differentiation may 

be difficult. However, careful watch at holes with fresh frass will often afford 

glimpes of worker ants ejecting fresh shavings; further disturbance may also 

bring a number of individuals to the surface. In addition, galleries of most 

wood borers are not kept as clean as those of carpenter ants. Earwigs (order 

Dermaptera), which may be found hiding in damaged wood, have prominent 

“pincers” at the end of the abdomen. 

Remarks: 

•	 Carpenter ants are important predators and scavengers, assist in 

decomposition of woody debris, and are important sources of food for 

other animals 

•	 Control may be very difficult but not usually necessary in a forest 

setting; populations can be high where trees have significant rot 

References: 10, 12, 19, 24, 37, 46, 56, 79, 89 

Figure 5. Carpenter ant galleries established in existing weakened wood 

WOOD & BARK BORING INSECTS
 

POPLAR CARPENTERWORM 

Acossus centerensis (Lintner) 	 Lepidoptera: Cossidae 

Distribution: Primarily eastern – in U.S. from NY and NJ west to IL and ND; 

in Canada from QU and ON west to SK and AB 

Hosts: Quaking aspen preferred; balsam 

poplar occasional host 

Identification: Adult moths have blackish 

head, thorax, and abdomen, edged and 

shaded with gray. A transverse row of white 

hairs (setae) on the thorax is highly visible 

on live specimens. Forewings are two-toned 

- black-gray near body and lighter gray on 

outer half - and are covered with a network of irregular black lines. Hindwings 

are rounded and translucent with indistinct black lines. Wingspan of male is 

40-50 mm; female is more robust with a wingspan of 50-64 mm. Females have 

thread-like antennae, while males have feathery antennae. Larvae are creamywhite with dark brown heads, strong black mandibles, and small brown spots 

(at setal bases). Thoracic shield is pale-yellow to blackish-brown. Anal shield is 

yellowish. Thoracic legs (three front pair) are well developed with black claws. 

Mature larvae are 32-45 mm long. Pupae are narrow, shiny, wrinkled, brownishblack, and around 30 mm long. 

Life History: Adults emerge during the day in early summer. However, they 

are most active at night, often resting on roughened areas of bark, bark scars, 

or broken limbs during the day. Females deposit 50 or more eggs, singly or in 

small groups, on bark, in tunnels, or in other bark openings. Larvae bore into 

bark and heartwood, often feeding in groups. Gallery openings are typically 

kept partly closed with packed frass and debris, with fine chips and thin slivers 

of wood loosely packed behind that. It is believed the poplar carpenterworm 

goes through a 2- or 3-year life cycle. Mature larvae pupate in innermost part 

of galleries with their heads toward openings. After slightly less than 1 month, 

pupae work their way to gallery entrance, and through chip and frass plugs. 

Moths emerge, often leaving an empty brown pupal case protruding from the 

exit hole. 

Damage: Larvae mostly attack stems (up to 41 cm diameter) and branches 

(smaller than 31 cm diameter). Bark scars often occur around open entry points 

and heavily infested trunks may have multiple entry points. Larvae make galleries 

Figure 1. Poplar carpenterworm adult 

32 
35 

 

WOOD & BARK BORING INSECTS
 

Key: 

• Debris-filled (plugged) entrance holes with frass and boring-dust in bark crevices and around base of tree 

• Bark scars around entry points 

• Brown pupal case protruding from exit hole 

• Adults gray with dark gray bodies, front wings distinctly two-tone - darker by the body and light toward outer 

end with irregular dark lines throughout 

Figure 2. Adult popular carpenterworm 

on finger 

up to 15 mm diameter running in diverse 

directions deep within the wood. Chambers up 

to 90 cm long have been found. Galleries end in 

smooth pupal cells about 40 mm long. Heavy 

infestations weaken trees structurally, make 

them susceptible to wind and snow breakage, 

and may ultimately cause mortality. 

Similar Damage: Damage by aspen carpenter 

worm (Acossus populi) is similar, making 

distinction between the two difficult where 

distributions overlap. Carpenterworm 

(Prionoxystus robiniae) also creates similar damage and boring debris, although 

holes are generally kept open. In addition, Prionoxystus larvae create an inner 

chamber at entry point up to 6 cm in diameter and leave behind webbing at bark 

surfaces or within exit tunnel. If adult moths are available, coloring of fore- and 

hind- wings can be used to readily differentiate species. Other moth borers in 

Sesia and Sthenopis are more likely to be found at or below soil line. 

Poplar borer (Saperda calcarata) will also create bark calluses around gallery 

openings and produce large boring debris, but no pupal case will exist at the exit 

hole. Adults and larvae of poplar borer (beetle) are also readily distinguishable 

from the moth borers mentioned. Most other aspen-stem boring beetles are 

buprestids whose larvae and adults tend to be smaller in size and create D-shaped 

or oval exit holes and galleries. Poplar-and-willow borer (Cryptorhynchus lapathi), 

a weevil, creates round holes and ejects copious amounts of frass but is much 

smaller in size. 

Remarks: 

•	 Natural control agents include an unidentified ichneumonid parasite 

(found in pupae), woodpeckers (eat larva), and ants (eat eggs) 

•	 Males are easily attracted to traps baited with synthetic sex pheromone 

References: 1, 12, 18, 37, 56, 91, 97, 98 

WOOD & BARK BORING INSECTS
 

ASPEN CARPENTERWORM 

Acossus populi (Walker)	 Lepidoptera: Cossidae 

Distribution: Reportedly coast to coast; known from NV, CO, CA, and 

northern Rocky Mountains, as well as BC and ON 

Hosts: Cottonwoods and poplars, especially quaking aspen; most Populus species 

Identification: Adult moths are large (50-80 mm wingspan), heavy-bodied, and 

light-gray. Thorax is gray, with a broken narrow white band bordered on either 

side by black. Abdomen is dull gray. Forewings are dirty white, crossed by a 

network of fine dark-gray broken lines. Two or more of these lines at wing center 

are usually darker, more prominent, and often partly joined. Hindwings are gray 

with a similar net of fine black lines. Females, distinguishable from males by 

slightly heavier bodies, are lighter gray color, have less distinct lines (reticulation) 

on hindwings, and possess thread-like antennae (serrate). Male antennae are 

somewhat feathery (narrowly bipectinate). Larvae are cream-colored, shiny, 

hairless, and have dark-brown head and thoracic shield. At maturity they are 

35-40 mm long. 

Life History: Adults emerge in July. Soon after, females deposit eggs in bark 

crevices of host trees, flying principally at night. Young larvae tunnel under 

bark initially and then excavate extensive 

galleries into wood. It is likely 2-3 years 

are required to complete their life cycle 

although little is actually know about 

these borers. They are considered similar 

to poplar carpenterworm (A. centerensis) 

but are more common in western North 

America. 

Damage: Bark scars often develop 

around entry points and frass can be 

found in bark crevices of actively infested 

trees. Multiple frass-filled entrance holes 

indicate degree of infestation. Galleries 

with blackened walls, up to 13 mm 

diameter, may extend deep into wood. 

Heavily infested boles may become so 

riddled with tunnels they break in wind 

or from snow loading. Populations 

Figure 1. Adult aspen carpenterworm (male upper 

and female lower) 

34 
37 

 

Figure 2. Adult aspen carpenterworm at rest 

WOOD & BARK BORING INSECTS 

Key: 

•	 Debris-filled (plugged) entrance holes with frass and boring dust in bark crevices and around base of tree 

•	 Bark scars around entry points 

•	 Brown pupal case protruding from an exit hole 

•	 Cream-colored, shiny, hairless larvae up to 4 cm long with dark brown heads and thoracic shields 

•	 Adults light gray with distinct white and black patches on thorax; wing span 5-8 cm; front wing with a net 

of black lines and hind wing light gray with net of faint black lines 

appear to be localized but widely 

scattered. 

Similar Damage: Damage by poplar 

carpenter worm (A. centerensis) is 

similar, making distinction between 

the two difficult where distributions 

overlap. Carpenterworm 

(Prionoxystus robiniae) also creates 

similar damage and boring debris, 

although entrance holes are generally 

kept open and free of frass. In addition, Prionoxystus larvae create a chamber 

under bark at entry point up to 6 cm in diameter, and leave behind webbing at 

bark surfaces or within exit tunnel. If adult moths are available, coloring of foreand hind-wings can be used to differentiate species. Other moth borers such as 

Sesia and Sthenopis are more likely to be found at or below soil line. 

Poplar borer (Saperda calcarata) will also create bark calluses around gallery 

openings and produce large boring debris, but no pupal case will exist at the exit 

hole. Adults and larvae of poplar borer (beetle) are also readily distinguishable 

from the moth borers mentioned. Most other aspen-stem boring beetles are 

buprestids whose larvae and adults tend to be smaller in size and create D-shaped 

or oval exit holes and galleries. Poplar-and-willow borer (Cryptorhynchus lapathi), 

a weevil, creates round holes and ejects copious amounts of frass but is much 

smaller in size. 

Remarks: 

•	 Adults are attracted to light, so can be collected at night 

•	 Natural control agents are likely similar to those of poplar carpenterworm 

(A. centerensis) including parasitic wasps, woodpeckers and ants 

•	 In CO found in conjunction with poplar borer (Saperda calcarata) where it 

appeared to preferentially lay eggs in old poplar borer egg scars 

References: 1, 4, 12, 18, 37, 52, 56, 91 

WOOD & BARK BORING INSECTS
 

CARPENTERWORM 

Prionoxystus robiniae (Peck) 	 Lepidoptera: Cossidae 

Distribution: Transcontinental 

Hosts: Quaking aspen noted as host, especially in 

Canadian literature; host preferences differ by area 

and include oaks (especially in East, South, and 

CA), green ash and elm (especially Prairie regions), 

poplars (especially in Rocky Mountain region) and 

other hardwoods such as willows, maples, black 

locust, and various fruit and ornamental trees and 

shrubs 

Identification: Adults are large, grayish, stoutbodied moths, with uniform mottling of gray and 

black scales over body and wings. Females with 60­

75 mm wingspans are much larger than males with 

less than 50 mm wingspans. Males have bright 

yellow-orange spot on hindwings. Both sexes have 

feathery (bipectinate) antennae. Eggs are 2.3 mm 

long by 1.5 mm wide ovals with a hard dark-olive 

brown shell and a net-like pattern of ridges. Young larvae are pinkish to dark 

brown, up to 7.5 cm long, with brown spots (at spiracles), and reddish-brown 

heads and thoracic shields. As larvae mature they gradually become greenish- or 

pinkish-white, with shiny dark-brown heads, black mandibles, and short, stout 

hairs on each body segment. Pupae are 30-50 mm long, torpedo shaped, darkshiny brown with circular 

bands of backwardpointing dark spines. Males 

and females have differing 

spine arrangement. 

Life History: Moths 

emerge from early spring 

to mid-summer (late April 

to early July) depending 

on region (latitude). 

Once mated, females deposit 200-1,000 eggs singly or often as small groups 

of 2-6 under bark crevices or other sheltered site (especially scabbed-over, old 

Figure 1. Adult arpenterworm on tree 

trunk 

Figure 2. Female (left) and male(right) carpenterworm moths 

36 
38 39 

WOOD & BARK BORING INSECTS 

Key: 

•	 Gallery open to outside or loosely plugged 

•	 Frass and boring dust caught in bark crevices and around base of tree 

•	 Presence of webbing either on bark or within gallery 

•	 Cave-like feeding gallery just under bark up to 6 cm diameter 

•	 Large, purplish-brown pupal case protruding from exit hole 

•	 Reddish-pink larvae with dark head when young, greenish- or pinkish-white larvae with dark-brown head 

when mature; stout hairs on each body segment 

•	 Adults with uniform mottling of gray and black; males differing greatly from female with bright yelloworange patches on hind wing 

wound sites). After 10-16 

days larvae hatch, construct 

loose webbed frass and bark 

shelters, and begin boring 

into the tree. Initially, young 

larvae feed just under bark 

in phloem, hollowing out 

irregularly shaped chambers 

up to 6 cm in diameter. 

Occasionally larvae wander 

out onto bark surfaces. After 

feeding, larvae move into 

sapwood and heartwood, 

creating 12-16 mm diameter, 

12-22 cm long galleries that 

slant upward before angling 

straight up. Gallery entrance 

remains open to the outside 

or loosely plugged with frass 

and boring debris. Larvae regularly return to area around entrance hole to feed 

on phloem and cambium, and to eject frass/boring dust. During spring of last 

year of development, full-grown larvae chew away sides of innermost part of 

galleries to facilitate exit of pupae. Tunnels are partially lined with yellowishbrown silken threads before pupating. Three to six weeks later, pupae wriggle 

to exits where moths emerge. Empty purplish-brown pupal cases often remain. 

Life cycle requires 1-4 years for completion depending on location; 1-2 years 

in south, three years in central and western U.S., and four years in southeast 

Canada. Overlapping larval generations often occur. 

Damage: In fall or spring following initial entry, spots of sap mixed with fine 

frass/boring dust begin to appear. Frass and boring debris can be found in 

bark crevices, and around bases of infested trees, becoming profuse. Irregular 

shaped chambers roughly 5 cm in diameter are formed just under bark by larvae 

Figure 3. Young (top) and mature (bottom) carpenterworm larvae 

WOOD & BARK BORING INSECTS 

returning to feed near gallery entrance. Inner surface of galleries is stained dark 

with stain moving into surrounding wood. Wounds heal in 1-2 years, leaving 

oval to irregular callused bark scars that remain for 10-20 years. Entry points 

around old scars are often re-infested. 

Trees are seldom killed, but severe 

infestations decrease rate of growth, 

compromise wood quality, provide 

entrance for decay organisms, and 

weaken structural integrity necessary 

to withstand strong winds. 

No tree size preference has been 

noted (found down to 5 cm diameter 

stems) but more open grown trees, 

especially ornamentals and those 

along shelterbelts, are often attacked. 

Carpenterworm is not known to 

attack dead trees, but it can complete 

its lifecycle in a tree after it has died. 

Similar Damage: Unlike most 

other wood borers, carpenterworm 

maintains tunnel opening clear of frass and boring dust. Other cossid moths, 

aspen carpenter worm (Acossus populi) and poplar carpenter worm (A. centerensis), 

create very similar damage and leave pupal cases behind, but do not create a large 

feeding chamber at entry point, or create webbing at bark surfaces (as small 

larvae) or within exit tunnel (before pupation). If adults are available, species 

can be separated by differences in wing coloring and pattern; females can be 

separated from similar aspen carpenterworm by the blotchy gray on forewings, 

and from poplar carpenterworm by gray hindwings. Other moth borers such as 

Sesia and Sthenopis are more likely to be found lower on stem at or below soil 

line. 

Poplar borer (Saperda calcarata) will also create bark calluses around gallery 

openings and produce large boring debris, but no pupal case will exist at the exit 

hole. Adults and larvae of poplar borer (beetle) are also readily distinguishable 

from the moth borers mentioned. Most other aspen-stem boring beetles are 

buprestids whose larvae and adults tend to be smaller in size and create D-shaped 

or oval exit holes and galleries. Poplar-and-willow borer (Cryptorhynchus lapathi), 

a weevil, creates round holes and ejects copious amounts of frass but is much 

smaller in size. 

Figure 4. Damage in Populus species 
41 

WOOD & BARK BORING INSECTS 

Remarks: 

•	 Damage in sawn lumber appears as 


pockets of ingrown bark and ovalto-irregular holes, 12 mm or larger 


diameter, surrounded by stained wood 


that can extend 60 cm up and down 


from the burrow
 

•	 Frass characteristics useful for 


identification against other species 


include:
 

o	 Excrement pellets and wood chips 


constitute equal proportions 


(>40%) of ejected frass; overall 


color light to dark brown; pieces 


may be loose or clumped
 

o	 Wood chips irregular in size and 


shape (max size 8 mm)
 

o	 Excrement pellets are cylindrical 


(max size 7 mm long by 3 mm 


wide) and usually darker than chips
 

o	 Silken thread occasionally present 

o	 Gallery entrances open or loosely plugged with frass 

•	 Carpenter ants may inhabit and further hollow out galleries 

•	 Newly emerged female moths may be so heavy with eggs they are unable to 

fly, resulting in many eggs being laid on the same tree from which females 

emerged 

•	 Females produce attractant pheromones able to lure males from long 

distances 

•	 Woodpeckers, predatory insects, parasitic wasps and other natural enemies 

suppress populations but not often below acceptable levels 

•	 Control measures include removal of brood trees, wrapping of small trees 

in May to prevent emergence of moths, probing holes with wire to kill 

larvae, pheromone attractants, and proper use of insecticides (e.g. on bark 

to prevent entry, or applied through gallery hole to kill larvae); because of 

long life cycle any treatment must be carried out over 3 or more years 

References: 1, 12, 13, 18, 20, 27, 37, 49, 56, 58, 84, 90, 91, 92, 95, 98, 105 

Figure 6. Typical gallery of carpenterworm with 

chamber just below bark 

WOOD & BARK BORING INSECTS
 

BRONZE POPLAR BORER 

Agrilus granulatus liragus Barter & Brown Coleoptera: Buprestidae 

[=Agrilus liragus Barter & Brown; =A. granulatus (Say)] 

Distribution: From BC, east to NL and NB, south to PA and northern CA and 

NV, possibly as far south as AZ 

Hosts: In addition to quaking aspen, common hosts include bigtooth aspen, 

balsam poplar, Russian poplar, black cottonwood and eastern cottonwood 

Identification: Adult beetles are 

6.8-11.5 mm long, flattened, 

and black with green iridescence. 

Males have a greenish head. 

Coppery reflections common in 

A. anxinus Gory (bronze birch 

borer, which it closely resembles) 

are nearly always lacking or never 

distinct. Eggs are oval (about 

1.2 by 0.8 mm), flattened, and 

creamy-white in color. Larvae 

are 30-40 mm long and 2-3.5 mm wide, flattened, with a whitish body, dark 

mandibles, and brown pincher-like projections at tail end (anal forceps). The 

prothorax also has a darker, median I-shaped line. 

Pupae are shorter and fatter than larvae, but are 

similar in color and begin to show vestiges of 

wings. 

Life History: Adults can emerge throughout 

summer, depending on weather. Adults feed for a 

week on foliage before females start to lay eggs in 

bark crevices. Normally 5-8 eggs are laid at a time 

(up to 18). Oviposition continues throughout 

summer, often on trees’ sunny side during warm 

days (27o

 C/ 80o F; rarely when below 21o C/ 70o 

F). After two weeks, emerging larvae tunnel into 

the phloem of branches and stems. Forays into 

sapwood may occur for each molt before larvae 

return to feeding in the phloem. Pupal chambers 

are formed in spring in either sapwood or in thick 

bark. Most larvae overwinter before pupating in 

Figure 1. Bronze poplar borer adult next to dime 

Figure 2. Bronze poplar borer larva 

in galleries; note tightly packed frass in 

chambers 

40 
42 43 

WOOD & BARK BORING INSECTS
 

Figure 3. Bronze poplar borer attacks are often visible as small pitch spots (left) until bark is peeled back to reveal 

the gallery (right) 

spring. Adult emergence holes from the bark are D-shaped; 3-4 mm diameter. 

Life cycle usually takes two years in vigorous trees and in northern climates; but 

may be completed in one year in weakened stems or warmer conditions. 

Damage: Larvae mine downward in a meandering course. Tightness of zigzag 

pattern is likely indicative of food quality with less compact (almost random) 

galleries found in more rapidly degrading tree tissues. Galleries are about 30-60 

cm long (up to 150 cm), widening from 0.6 mm to 3.0 mm as larvae mature, 

and are packed with frass. First instar larvae bore directly to the cambial layer. 

Occasionally, larvae will mine into the xylem to molt but return to phloem to 

continue feeding, lengthening the tunnel. In decadent trees, molting excursions 

are rarer. Larvae create pupal cells in outer xylem or bark, if bark is thick enough, 

and create partial exit holes for adult emergence the following spring. 

There can be leaf discoloration and some defoliation after initial attack. In 

sufficient numbers, boring can girdle branches and stems. Boring also introduces 

or makes conditions conducive to a variety of canker disease, and can make trees 

attractive to other insects such as poplar borer (Saperda calcarata). 

This species is an early colonizer of weakened and dead wood, and can become 

very abundant in the first year after a tree’s death. It contributes to wood decay 

processes and provides food for wildlife such as woodpeckers. Vigorously 

growing trees are likely unsuitable for larva development and survival, although 

if populations become high, more healthy trees may be attacked. Stressed trees 

WOOD & BARK BORING INSECTS 

Key: 

•	 Spot of sap on bark surface with little to no other early signs of attack; no ejected frass from entry hole 

•	 D-shaped, 3-4 mm diameter adult emergence holes in bark on dead stem or branch 

•	 Zig zag gallery in phloem ranging from tight to nearly random pattern, 30 to 60 cm long, with or without 


holes into wood
 

Figure 4. Bronze poplar borer larval galleries created in weakened trees are widely spaced and random (left); in 

healthy trees, galleries are closely spaced, tight zigzags (right) 

are preferred with known predisposing factors including defoliation, cankers, 

ungulate bark damage, wind breakage and drought. 

Similar Damage: Poecilonota species and, to some extent, flatheaded poplar 

borer (Dicerca tenebrica) are most similar in gallery pattern, exit hole shape, and 

host material used. Unlike some other aspen wood borers, there is no external 

frass or sap flow due to bronze poplar borer activity. However, eastern poplar 

buprestid (P. cyanipes) and likely other Poecilonota species also eject little to no 

frass. A tight zigzag gallery is often indicative of bronze poplar borer although 

in degraded hosts the more open, random pattern can resemble those of several 

other buprestid wood borers. Smaller size of D-shaped holes made in bark 

during emergence and in wood during larval molting excursions may be useful. 

Remarks: 

•	 Agrilus granulatus has been divided into numerous subspecies based on 

color, morphology of genitalia, and preferred host plants: subspecies A. g. 
45 

 

WOOD & BARK BORING INSECTS 

granulatus (Say) (granulate poplar borer) and A. g. populi Fisher (western 

poplar agrilus) are found in eastern and western North America, respectively, 

with both found in MT. Agrilus granulatus mohavei Knull has been noted in 

southern CA in fremont cottonwood; although all subspecies attack Populus 

species, only A. g. liragus is in aspen 

•	 Recent studies suggest bronze poplar borer is more important in aspen 

stem health than previously expected, partly due to its cryptic entrance 

hole and common association with cankers; was associated with rapid aspen 

mortality (sudden aspen decline or SAD), observed in the central Rocky 

Mountains, 2008-2010 

•	 Host quality effects length of life cycle, gallery shape and size, frequency of 

excursions into wood, and survival of larvae and emerging adults 

•	 Natural enemies include numerous egg and larvae parasites as well as 

woodpeckers; reportedly woodpeckers can consume up to 40% of pupating 

and emerging adults on individual, standing trees 

•	 Control includes maintaining healthy trees, cutting and destroying infested 

trees or limbs, and applying a pesticide recommended for wood-boring 

insects in early summer 

References: 1, 3, 9, 10, 12, 13, 17, 18, 20, 37, 47, 52, 54, 55, 56, 58, 59, 64, 

69, 78, 87, 91, 94, 95, 98, 104 

WOOD & BARK BORING INSECTS
 

GOLD DUST BUPRESTID 

(YELLOW SPOTTED JEWEL BEETLE) 

Buprestis confluenta Say Coleoptera: Buprestidae 

[=B. tesselata Casey] 

Distribution: Found from BC east 

to QU, south to AR, TX and CA; in 

U.S. collections noted from CA, CO, 

NE, KS, TX, MO and AR 

Hosts: Populus species noted, with 

eastern cottonwood, balsam poplar 

and quaking aspen identified 

specifically; in KS and Canada found 

in trees along river sides 

Identification: Adults are metallic 

wood-boring beetles (“jewel beetles”) 

easily identified by yellow spots 

covering brilliant-green elytra, 

although elytra are occasionally coppery-brown or purplish-blue. Yellow flecks 

may be widely separated to almost confluent. Head and pronotum are usually 

solid metallic green, tips of elytra are usually coppery. Beetles range in length 

from 12-20 mm and width 5-7 mm—males about 15 mm long and 5-6 mm 

wide, females about 17 mm long and 7 mm wide. Eggs are not described but 

likely are small, white and oval as with other buprestids. Larvae are typical of 

other flathead borers. Pupae are not described but are likely similar to those of 

other buprestids, somewhat smaller than adult beetles, soft, creamy white, with 

signs of wing development. 

Life History: Little is known about this woodborer, although it is likely they 

have life histories similar to other buprestids (e.g. two-year life cycle or greater). 

Adults are active from late June through August; often found sunning themselves 

on the south facing side of stems. 

Damage: Beetles appear to prefer decadent and dying trees. In Canada they’ve 

been found using logs drifting in water. Galleries are made in phloem and 

sapwood, typically winding and flattened. 

Similar Damage: This beetle is relatively uncommon, suggesting that if damage 

to aspen appears to have been caused by a buprestid-like woodborer, it is likely 

Figure 1. Adult gold dust buprestid 

44 
47 

 

WOOD & BARK BORING INSECTS 

Key: 

• Beetle with metallic green elytra covered in yellow spots 

• D-shaped exit hole similar to other buprestids 

to be from a different beetle. Most 

other buprestid wood borers in 

aspen stems, especially flatheaded 

poplar borer (Dicerca tenebrica) 

and poplar buprestids (Poecilonota 

spp.) are likely to create similar 

damage, choose similar host 

material, and create similar 

galleries and frass. However, 

adult beetles of B. confluenta are 

unmistakable. 

Although most Buprestis species 

attack conifers, another “jewel 

beetle”, Buprestis viridisuturalis 

Nicolay and Weiss [=B. lesnei 

Garnett], reportedly attacks 

Populus and Alder species in the 

western U.S. (WA, OR, CA and 

UT noted). However, it has not 

been reported to attack quaking 

aspen and adult beetles are 

distinctly different in appearance. 

Remarks: 

References: 9, 13, 20, 37, 39, 54, 55, 61, 69, 71, 96, 98 

Figure 2. Adult Buprestis viridisuturalis 

WOOD & BARK BORING INSECTS
 

FLATHEADED APPLETREE BORER 

Chrysobothris femorata (Olivier) Coleoptera: Buprestidae 

[=Buprestis femorata Olivier] 

Distribution: Found from BC to NB, south to Mexico; is more common east of 

Rocky Mountains, while similar Pacific flatheaded borer (C. mali) predominates 

in Rocky Mountains and west 

Hosts: Maple and apple preferred but 

a wide range of shrubs, and deciduous 

fruit, forest and shade trees may be 

used including many Populus species; 

adults noted on aspen in AB and other 

areas 

Identification: Adults are metallic 

olive-gray to brown beetles with a 

broad oval shape, measuring 7-16 

mm long (average 12 mm) and up 

to 5-7 mm wide. They are marked with dull gray spots or bands. Elytra are 

black with coppery-bronze luster, but beneath the beetle’s wings its body is a 

metallic greenish-blue. Most striking is the vivid green front of the head. Eggs 

are pale yellow, flattened, disk-like, wrinkled and 1.5 mm in diameter. Larvae 

are yellowish-white, legless and 18-25 mm long. Heads are brown with first 

thoracic segment broad, flattened, and hardened. The next two segments are also 

flattened—resulting in the characteristic “horseshoe nail” shape of flatheaded 

wood borers. Pale yellow pupae, 7-19 mm long, resemble adults in shape and 

size. 

Life History: Adult beetles can be found from early spring through late fall 

but are most abundant in late-May through June. After exiting host, females 

mate, begin ovipositing in 4-8 days, and live about a month. Females lay 

approximately 100 eggs, singly, in cracks or crevices of bark. Eggs hatch in 8-16 

days. First-instar larvae chew directly into bark and feed in phloem and surface 

of sapwood. As soon as larvae are fully developed, they tunnel from cambium 

deeper into sapwood. Later instar larvae prepare pupal chambers by plugging 

burrows tightly with frass. Larvae become dormant in cold weather, overwinter 

in these chambers, pupating in the spring for 8-14 days. Adults emerge by 

cutting D-shape exit holes through bark. Beetles typically have a one-year life 

cycle although 2-3 years may be necessary in some northern areas. 

Figure 1. Adult flatheaded appletree borer 

46 
48 49 

WOOD & BARK BORING INSECTS 

Key: 

•	 White, frothy sap oozing from cracks in bark 

•	 Broad, metallic olive-gray to brown beetle with dull gray spots 

•	 Larvae and D-shaped exit hole similar to other flatheaded woodborers 

Damage: White, frothy sap oozes 

from cracks in bark of infested trees. 

Bark gradually becomes darkened, 

wet, and greasy appearing. Galleries, 

packed tightly with fine, sawdust-like 

frass, are broad and have many curves 

and bends. Little to no boring dust is 

ejected except at bark cracks. Areas of 

larval feeding often become depressed, 

and bark may eventually split at 

injured sites. Burrows in older trees 

with thick bark may be confined to a 

circular area. Wounds may be enlarged 

by succeeding generations. 

Trunks and branches are attacked, 

most commonly on sunny aspects, often concentrating on trees suffering from 

sunscald, drought stress, transplanting or wounding. In young trees 5 cm 

diameter or less with thin bark, tunnels sometimes encircle and girdle stem. 

In weakened trees, larvae develop rapidly and produce long burrows; but in 

vigorous trees, larvae tend to develop slowly, and many do not survive. Old 

woodlands or declining orchards can harbor high numbers, causing significant 

damage to new plantings made in close proximity. 

Similar Damage: Where species ranges overlap, type of damage and size of 

galleries may be very similar to other buprestid wood borers such as Poecilonota, 

Chrysobothris, Dicerca and Buprestis species. Adult beetles may be needed to 

separate these damage agents. These buprestids leave oval or D-shaped holes 

slightly smaller than the large (~10mm wide), perfectly round holes of the 

cerambycid, poplar borer (Saperda calcarata) or the oval to irregularly shaped, 

large holes (9-15mm wide) of some moth borers (e.g. carpenterworms). Bronze 

poplar borer (Agrilus granulates liragus) is a much smaller buprestid with an oval 

or D-shaped exit hole only 3-4 mm in diameter. 

Remarks: 

•	 Beetles move rapidly, running quickly over trunk surfaces or taking flight 

when disturbed; at rest, adults prefer sunny sides of trunks and larger 

branches 

Figure 2. White oozing spot at point of entry of 

flatheaded appletree borer 

WOOD & BARK BORING INSECTS 

•	 Control: Hymenopterous 


parasites and insect predators 


help reduce infestations, 


however, maintaining healthy 


trees is most important practice; 


removal of infested material 


will help reduce populations 


but unnecessary cutting and 


damage should be avoided; 


because young transplants are 


particularly susceptible, additional 


precautions such as wrapping 


trunks or protecting from sun 


may be helpful; chemical controls 


may occasionally be required in 


nursery settings 


References: 1, 3, 9, 10, 17, 18, 20, 22, 37, 56, 58, 59, 81, 91, 98 

Figure 3. Flatheaded appletree borer larva 
51 

 

WOOD & BARK BORING INSECTS
 

PACIFIC FLATHEADED BORER 

Chrysobothris mali Horn	 Coleoptera: Buprestidae 

Distribution: Occurs along West Coast into Rocky Mountain states and 

provinces including southern BC, AB and southern MB 

Hosts: lder, birch, ash, oak, willow, poplar, 


elm, sycamore and over 60 other species, in 


over 40 genera in 21 plant families; Populus
 

species not preferred and quaking aspen not 


commonly used 


Identification: Adults are flattened, darkbronze to reddish-copper beetles, 6-11 mm 

long, with distinct copper spots and short 

inconspicuous white hairs covering elytra. 

Eggs, about 1 mm diameter, are disk-shaped, yellowish-white, and deposited 

within bark crevices or depressions. Larvae vary from yellowish-white to yellow 

and are 15-18 mm long when mature. Thoracic segments are greatly enlarged 

and flattened. Larvae curve their abdomen and appear hook-like or U-shaped 

when exposed in feeding chambers. Pupae, 6-11 mm long, are translucent-white 

when first formed, then darken to bronze until adult emergence. 

Life History: Adults emerge from pupation sites from April through August, 

but are most commonly seen in June and July. Soon after emergence, mating 

and egg-laying begin. Females lay up to 100 eggs, deposited singly, but may 

be adjacent enough to form clusters. Once hatched, larvae bore directly into 

bark. Larval mining tends to occur in cambium until fall when larvae tunnel 

into sapwood to overwinter. Before 

molting into last larval instar, mature 

larvae construct pupal chambers in 

tree’s heartwood. Larvae overwinter 

as prepupae—pupating the following 

spring for 8-14 days. Adults emerge 

from pupal cells, chewing their way 

to the outside through a 6.3 mm 

oval-shaped hole. Usually, there is 

one generation per year; but life cycle 

may be longer at higher elevations and 

northern portions of beetles’ range. Figure 2. Bark loosens and drops away above tunnels of 

Pacific flatheaded borer galleries. 

Figure 1. Pacific flatheaded borer adult 

WOOD & BARK BORING INSECTS 

Key: 

•	 Similar in most traits to flatheaded appletree borer but more common in the West 

•	 Uncommon on aspen 

Damage: Quaking aspen is not commonly 

attacked, although Pacific flatheaded borer has 

a wide host range. Feeding results in unusually 

dark, wet spots appearing on tree’s bark that 

may later crack slightly to expose boring 

chambers. White, frothy sap can ooze from 

bark cracks. Tunnels under bark are broad, 

oval-shaped, follow a very irregular pattern, 

and are packed with powdery boring dust and 

frass. Very little frass is ejected from the tree. 

Spiraling galleries can girdle branches or trunks 

of small trees. Infestations can occur over any 

part of a mature tree although attacks on young 

trees are generally limited to the larger trunk. As galleries grow, bark cracks and 

loosens above them. As bark drops away, ugly canker-like spots often result. Bark 

of infested trees may become heavily scarred. It is considered one of the most 

injurious enemies of newly planted trees and shrubs; young-stem girdling and 

branch mortality is common. However, boring activity rarely kills older trees. 

Similar damage: Where species ranges overlap, type of damage and size of 

galleries may be very similar to other buprestid wood borers such as Poecilonota, 

Chrysobothris, Dicerca, and Buprestis species. Adult beetles may be needed to 

separate these damage agents. These buprestids leave oval or D-shaped holes 

slightly smaller than the large (~10mm wide), perfectly round holes of the 

cerambycid, poplar borer (Saperda calcarata), or the oval to irregularly shaped, 

large holes (9-15mm wide) of some moth borers (e.g. carpenterworms). Bronze 

poplar borer (Agrilus granulates liragus) is a much smaller buprestid with an oval 

or D-shaped exit hole only 3-4 mm in diameter. 

Remarks: 

•	 Field observations suggest birds remove immature stages of the borer from 


infested trees, and larval parasites can affect larval populations; the mite 


Pyemotes bentricosus (Newport) predates on larvae in their tunnels
 

References: 3, 9, 10, 18, 20, 37, 58, 59, 91, 98 

Figure 3. Bark often cracks, above tunnels 

of Pacific flatheaded borer galleries (on 

sycamore) 

50 
53 

 

WOOD & BARK BORING INSECTS
 

POPLAR-AND-WILLOW BORER 

Cryptorhynchus lapathi (L.) Coleoptera: Curculionidae 

[=Sternochetus lapathi (L.)] 

Distribution: Found throughout southern Canada and northern U.S. 

Hosts: Willow preferred; Populus species (mainly black cottonwood, balsam 

poplar, and hybrid poplars) also used; quaking aspen, paper birch and alder 

rarely attacked in forest setting 

Identification: Both male and female adults are rough-surfaced, snout-nosed 

weevils, about 8-10 mm long. They are mostly dull, dark brown to black, and 

mottled with light brown and 

gray scales. The hind third of 

their elytra are usually gray; 

sides of thorax and parts of legs 

may be whitish or pinkish. Eggs 

are 1.1 mm by 0.8 mm, white, 

found in groups of 1-4. Larvae 

are creamy-white, C-shaped, 

legless grubs with reddish-brown 

heads and a full-grown length of 

approximately 1 cm. Pupae are 

likely whitish and about 1 cm in 

length. 

Life History: The poplar-and-willow borer can require up to 2-3 years to 

complete its life cycle. Oviposition takes place in summer when females make 

small punctures in bark, usually around the base of shoots, favoring scars, wounds, 

or lenticels. When the puncture is 

as deep as her beak can reach, the 

female lays 1-4 eggs in each puncture, 

covering them with fine wood chips. 

Once eggs have hatched, larvae feed 

under the bark then move upward 

into the sapwood. Larvae pupate 

within wood chip-filled chambers. In 

northern climates, both adults and 

larvae overwinter in galleries, but in 

more temperate climates adults emerge 

from their pupal cells in autumn and 

Figure 1. Adult poplar-and-willow borer 

Figure 2. Poplar-and-willow borer larvae found in 

chambers constructed within young aspen stems 

WOOD & BARK BORING INSECTS 

hibernate on the ground during winter. Adults 

are found in the trees in spring and early summer 

but do not lay eggs until July or August. These 

adults may live through two summers. 

Damage: Larvae initially expel frass, which is 

found mixed with oozing sap on bark outside 

of holes. Later, frass is found in tunnels. 

Young stems, 2.5-10 cm diameter, are infested 

primarily around the base, and are killed by 

larvae mining or by breakage of weakened 

stems. Adult weevils may also cause injury by 

feeding on succulent bark of branches or main 

stem before mating. 

The most pronounced injuries are old bark 

scars that are horizontal and deep, and often 

have right angle extensions and exposed stained wood. Stems that have been 

repeatedly attacked are often honeycombed with tunnels making them 

susceptible to decreased wood quality, breakage, and mortality. Stems in moist 

areas along streams and ponds are frequently attacked. 

Similar Damage: Aspen root girdler (Agrilus 

horni) is the wood borer most similar in host 

size preference (<18 cm) and location of attack 

near ground. However, it is more commonly 

found in aspen and attacks lower on the stem, 

at or below soil line. The spiraling damage by 

aspen root girdler is diagnostic, and adults 

and larvae differ greatly in conformation. 

Poplar-and-willow borer is not likely to be 

confused with other insects more common 

in aspen stems due to its smaller larval size, 

smaller round exit hole, and adult/larva 

conformation. Callusing around entry hole 

and large amounts of boring dust may appear 

similar to poplar borer (Saperda calcarata). 

Attacks in the crown may be more difficult to 

differentiate from other frass-ejecting wood 

borers. Stem swelling resulting from poplar-and-willow borer feeding may be 

rougher with more frass than swellings from other gall forming insects that use 

young stems. 

Figure 3. Frass pushed out of chamber by 

poplar-and-willow borer larvae is often mixed 

with sap 

Figure 4. Poplar-and-willow borer damage 

52 
55 

 

 

 

 

WOOD & BARK BORING INSECTS
 

Key: 

• Attacks stems 2-8 cm diameter near ground line or at branch junctions 

• Frass on ground or clinging to bark at hole entrance, often with sap oozing from bark 

• Old bark scars that are horizontal and deep, often with extensions at right angles and stained wood 

• Uncommon in wild stands of quaking aspen; may be common in ornamental trees 

Remarks: 

•	 Common in ornamental aspen in 

northern ID 

•	 Native to Europe and Asia, 

introduced into northeastern U.S. 

before 1882 

•	 Weevils seldom fly and poplarand-willow borer is no exception; 

if alarmed, they play dead, falling 

to the ground and lying motionless 

•	 When held, adults of both sexes 

squeak by rubbing their abdomens 

with the inside of their elytra 

•	 Adults inactive during the day if 

temperatures are greater than 26 ° 

C (79° F) 

•	 Adult coloring make them look 

somewhat like a bird dropping Figure 5. Poplar-and-willow borer damage in young 

stem 

Figure 6. Branch swellings and damage from poplarand-willow borer 

References: 1, 3, 10, 12, 13, 18, 20, 35, 36, 37, 38, 50, 58, 77, 78, 84, 91, 95, 

WOOD & BARK BORING INSECTS
 

(A FLATHEADED BORER) 

Dicerca callosa Casey 	 Coleoptera: Buprestidae

 D. callosa callosa Casey

 D. callosa frosti Nelson 

[=D. rigida Casey; D. tetrica Casey; D. frosti Nelson] 

Distribution: Subspecies D. c. callosa widespread throughout Canada, AK 

and northern portions of central and eastern U.S. while D. c. frosti is found 

throughout western U.S. and southern end of BC and AB 

Hosts: D. c. frosti is found on aspen; D. c. callosa most commonly collected on 

quaking aspen which is its suspected host; also found on birch, willow, jack pine, 

and eastern white pine although these are not likely hosts 

Identification: Adults are robust, elongate, and 

moderately convex beetles. Both subspecies are bronzy to 

coppery-black above, and coppery below. Size averages 

16.5 mm long and 6.0 mm wide, but can range from 12.3­

20.7 mm long and 4.2-7.7 mm wide with D. c. frosti of 

larger average size. Likely, eggs are small, round, and 

off-white; larvae are cream-colored, legless, with a shape 

typical of buprestids (flatheaded borers), and pupae are 

creamy white and about the size of an adult beetle. 

Life History: Little information is available on the life 

cycle of this beetle but D.c. callosa has been collected from 

May to September, and D. c. frosti from April to August. 

Damage: Information 

on this species is lacking 

but it appears to be of limited impact on aspen 

forests. It may have habits somewhat like those 

of other Dicerca species, selecting stressed trees 

and contributing to introduction of pathogens. 

Similar Damage: This woodborer is similar in 

size and damage to other Dicerca, Chrysobothris, 

Poecilonota and Buprestis buprestid wood 

boring beetle species but does not appear to be 

very common. These buprestids leave oval or 

D-shaped holes slightly smaller than the large 

Figure 1. Adult Dicerca 

callosa callosa 

Figure 2. Close-up of smooth areas on 

pronotum of adult Dicerca callosa callosa 

54 

99 
57 

 

 

WOOD & BARK BORING INSECTS 

Key: 

•	 Difficult to differentiate from other buprestid woodborers of similar size; adults are likely necessary for 

species identification 

(~10mm wide), perfectly round holes of the cerambycid poplar borer (Saperda 

calcarata), or the oval to irregularly shaped, large holes (9-15 mm wide) of some 

moth borers (e.g. carpenterworms). Bronze poplar borer (Agrilus granulates 

liragus) is a much smaller buprestid with an oval or D-shaped exit hole only 3-4 

mm in diameter. 

Remarks: 

References: 3, 20, 54, 70, 98, 101 

WOOD & BARK BORING INSECTS
 

FLATHEADED POPLAR BORER 

(POPLAR DICERCA) 

Dicerca tenebrica (Kirby) Coleoptera: Buprestidae 

[= D. prolongata LeConte; D. longipennis Casey; D. pertinax Casey; D. severa 

Casey; D. subargentea Casey; D subcuprea Casey, D. sulcatula Casey] 

Distribution: Transcontinental 

Hosts: Common in quaking aspen; other commonly recorded hosts include 

bigtooth aspen, black cottonwood, narrowleaf cottonwood, and balsam poplar; 

boxelder and willow listed but unlikely 

Identification: Adults are robust, elongate and moderately convex beetles 

approximately 19.5 mm long and 

6.5 mm wide (range of 14.5-26 mm 

long and 4.5-9 mm wide). Their 

elytra have small, inconspicuous, 

black raised areas and prolonged 

narrow tips. Narrow, sometimes 

shallow grooves (striae) run the 

complete length of elytra to apex. 

Color is brassy-to-black with a bluish 

tint. Underside of beetle is coppery. 

Eggs are small, round, and off-white. 

Larvae are cream-colored, legless, 

with a shape typical of buprestid 

borers. Pupae are creamy white and 

about the size of an adult beetle. 

Life History: Adults are present from March to November. Females lay eggs 

during mid- to late-summer (July-Aug.) mostly around branch stubs and 

branches, and on rough bark. Sun-loving adults prefer to oviposit on trunks 

exposed to sunlight. Life cycle may be 2-5 years. 

Damage: Larvae bore down through bark into sapwood. Tunnels are elliptical in 

cross section and packed with granular frass and boring dust. Adults make rather 

large oval openings in bark as they emerge (likely same 4.5-9 mm width of the 

beetle). Wounded, sickly, and recently dead trees are most likely to be attacked. 

Beetles are also attracted to fire-killed aspen. Beetles boring in downed logs have 

also been reported. Flatheaded poplar borer has been directly associated with 

presence of hypoxlyon canker (Entoleuca mammata [Wahlenb.] J.D. Rogers & 

Y.M. Ju) and increased decadence of poplar stands. 

Figure 1. Adult flateheaded poplar borer and its ovalshaped exit hole 

56 
59 

 

WOOD & BARK BORING INSECTS 

Key: 

•	 Fine granular sawdust in and around exit holes 

•	 Large (maybe up to 9 mm wide), oval hole in wood and bark 

•	 Difficult to differentiate from other buprestid woodborers of similar size; adults are likely necessary for 

species identification; common 

Similar Damage: This woodborer 

is similar in size and damage to 

several other Dicerca, Chrysobothris, 

Poecilonota and Buprestis buprestid 

wood boring beetle species but appears 

to be more common in aspen than 

most other species. These buprestids 

leave oval or D-shaped holes often 

slightly smaller than the large (~10mm 

wide), perfectly round holes of the 

cerambycid, poplar borer (Saperda 

calcarata), or the oval to irregularly shaped, large holes (9-15mm wide) of some 

moth borers (e.g. carpenterworms). Bronze poplar borer (Agrilus granulatus 

liragus) is a much smaller buprestid with an oval or D-shaped exit hole only 3-4 

mm in diameter. 

Remarks: 

•	 These beetles breed in quaking aspen trees but can often be found sitting on 

trunks of other tree species within an aspen stand 

•	 In CO found in conjunction with poplar borer (Saperda calcarata) where it 

will lay eggs in old poplar borer egg scars 

•	 The species D. divaricata (Say) (flatheaded hardwood borer) , nearly 

identical in size and coloration (also found throughout U.S. and Canada), 

does not use quaking aspen; however, D. callosa Casey, a bit smaller in size, 

does 

•	 Dicerca and Poecilonota adults look similar except Dicerca are wider, more 

stout, with smooth linear patches on pronotum on either side of, but not 

on, the centerline 

References: 1, 3, 9, 10, 13, 20, 23, 37, 41, 47, 52, 54, 59, 63, 70, 94, 91, 95, 98 

Figure 2. Adult flatheaded poplar borer (right) is larger 

than bronze poplar borer (left) 

WOOD & BARK BORING INSECTS
 

WESTERN POPLAR BUPRESTID 

Poecilonota californica (Chamberlin) Coleoptera: Buprestidae 

[=Descarpentriesina californica (Chamberlin)] 

Distribution: In the western U.S. from OR, south to CA, east to ID, NV and 

TX (from West coast into Rocky Mountains) 

Hosts: Quaking aspen and cottonwood recorded; other Populus species probably 

also used 

Identification: Adults are 

moderately broad, robust beetles; 

9-18 mm long and 4-8 mm wide. 

Females are typically slightly larger, 

more robust and darker than males. 

Coloring ranges from gray-brown 

to dark bronze to almost black. 

Heads are coppery green and dark 

coppery; antennae are blue green. 

Elytra are usually coppery bronze 

with elongate raised greenish areas. 

Although not described, based on 

similar species it is likely eggs are 

small, round, off-white, and laid 

individually in bark crevices, larvae 

are cream-colored, legless, with a shape typical of buprestids, and pupae are 

creamy white and about the size of an adult beetle. 

Life History: Adults emerge during mid-summer. Larvae mine under the bark 

and into sapwood and heartwood extending galleries much more horizontally 

than vertically, sometimes venturing to the center of the tree. Frass is found 

packed tightly in the oval-shaped galleries. Lifecycle is likely 1-2 years. 

Damage: Tree trunks and large branches may be attacked. Attacks are much 

more likely to be found in young trees than older ones, and at higher elevations 

than at lower ones. Burrowing regularly results in small patches of bark turning 

black and peeling away although swelling sometimes develops over tunnels. 

Oval exit holes are left in the bark by emerging beetles (likely the 4-8 mm width 

of adult beetles). Infested trees commonly remain thrifty despite the burrowing; 

however, small trees can be girdled. Tunneling can also result in weakening of 

Figure 1. Western poplar buprestid adult; note the 

smooth patch down centerline of pronotum 

58 
61 

 

WOOD & BARK BORING INSECTS
 

Key: 

• Oval exit holes 4-8 mm wide 

• Club-like larvae, with flattened heads and thoraxes tunneling in oval shaped, frass packed chambers of 

younger stems 

stems so that breakage occurs at point of injury. 

Similar Damage: Where species ranges overlap, type of damage and size of 

galleries may be very similar to other Poecilonota species, including the common 

eastern poplar buprestid (P. cyanipes). Also similar is damage by Dicerca, 

Chrysobothris, and Buprestis species, buprestid wood borers of similar size. Adult 

beetles may be needed to differentiate these damage agents. These buprestids 

leave oval or D-shaped holes slightly smaller than the large (~10mm wide), 

perfectly round holes of the cerambycid, poplar borer (Saperda calcarata), or the 

oval to irregularly shaped, large holes (9-15mm wide) of some moth borers (e.g. 

carpenterworms). Bronze poplar borer (Agrilus granulatus liragus) is a somewhat 

smaller buprestid with an oval or D-shaped exit hole only 3-4 mm in diameter. 

Remarks: 

•	 Western popular buprestid and other Poecilonota species are more narrow 

than Dicerca and Chrysobothris species in aspen, and have a smooth linear 

patch running from front to back on their pronotum; Dicerca species in 

aspen have smooth patches on either side of, but not on, the centerline 

References: 14, 54, 55, 69, 91 

WOOD & BARK BORING INSECTS
 

EASTERN POPLAR BUPRESTID 

(BLUE FOOTED POPLAR BUPRESTID) 

Poecilonota cyanipes (Say) Coleoptera: Buprestidae 

[=Descarpentriesina cyanipes (Say)] 

Distribution: YT south along Rocky Mountains to southern AZ, eastward 

along the Gulf coast, north to NB; not along Pacific Coast (P. californica is 

present along Coast, overlapping in Rocky Mountains) 

Hosts: Eastern cottonwood, black cottonwood, bigtooth and quaking aspen, 

and willows 

Identification: Adults are elongate to 

moderately slender, somewhat oval, dark 

bronze beetles (9-18 mm long, 3-7 mm 

wide). Head and pronotum are slightly 

flattened and have relatively little hair. Elytra 

are dark-bluish bronze, with abbreviated, 

elevated, irregular lines tinged with coppery 

bronze. Females are slightly broader and 

darker than males. Eggs are likely small, 

white, and laid individually in bark crevices. 

Larvae are yellowish-white with dark-brown 

heads, 17-25 mm long, and moderately 

flattened as is typical for buprestid larvae. 

Pupae are likely creamy white and nearly the 

size of an adult beetle. 

Life History: Adults emerge from pupation sites between May and September, 

depending on latitude and/or elevation. On sunny days, adults are frequently 

found resting, crawling, and ovipositing on aspen bark. Females prefer weakened 

stems as oviposition sites. Larvae initially excavate small cavities just under bark, 

then extend galleries into sapwood. In larger stems, larvae burrow to about 12 

mm deep within stem, then continue longitudinally. Larvae overwinter in their 

galleries. Mature larvae eventually prepare chambers in which to pupate. New 

adults gnaw 2-5 mm wide, oval exit holes. A generation is completed in 1-2 

years. 

Damage: This beetle commonly attacks stems 12-32 mm diameter, but can be 

found in stems up to 75 mm diameter. Galleries are oval to irregular in crosssection, 6.4 mm diameter, and extend 6-13 mm into sapwood before running 

5-30 cm longitudinally within stems. Earliest evidence of infestation is small 

Figure 1. Eastern poplar buprestid adult 

60 
62 63 

WOOD & BARK BORING INSECTS 

Key: 

•	 Inconspicuous spot of sap on bark at entry point, sometimes developing into a round or oval sunken area, 

or with bark cracking to expose cavities 

•	 Little or no frass ejected from galleries 

•	 Frass-packed oval shaped gallery extending into wood; exit hole 2-5 mm elongate, oval 

•	 Club-like shaped larvae with thoracic segments and head moderately flattened 

wet or stained spots on bark. Also, 

irregularly shaped scars can be found at 

entry points and small oval-to-round 

scars around oval-shaped, 2-5 mm, 

exit holes. Galleries are almost entirely 

filled with a tightly packed frass/wood 

mixture of fine particles and short 

fibers; little or none of which is ejected. 

Bark sometimes cracks open, exposing 

residue-packed cavities. Beetles usually 

attack branches that are weakened, 

injured, or decadent; sometimes using 

other insect exit holes and galls as 

access sites. Weakened lower limbs that become infested are naturally pruned; so 

healthy part of tree is not affected. 

Similar Damage: Where species ranges overlap, type of damage and size of 

galleries may be very similar to other Poecilonota species. Also similar is damage 

by Dicerca, Chrysobothris, and Buprestis species, buprestid wood borers of similar 

size. Adult beetles may be needed to differentiate these damage agents. These 

buprestids leave oval or D-shaped holes smaller than the large (~10mm wide), 

perfectly round holes of the cerambycid, poplar borer (Saperda calcarata), or the 

oval to irregularly shaped, large holes (9-15 mm wide) of some moth borers (e.g. 

carpenterworms). Bronze poplar 

borer (Agrilus granulatus liragus) is 

a somewhat smaller buprestid that 

leaves an oval or D-shaped exit 

hole 3-4 mm in diameter. 

Remarks: 

•	 Found to sometimes breed 


in stem galls formed by 


poplar gall saperda (Saperda 


inornata) on willow and 


bigtooth aspen; unsure if 


same occurs in quaking aspen
 

Figure 2. While occasionally found in aspen boles, 

eastern poplar buprestid larvae are often found in smaller 

branches 

Figure 3. Multiple eastern poplar buprestid larvae in branches 

WOOD & BARK BORING INSECTS 

•	 In CO found in conjunction 


with poplar borer (Saperda 


calcarata) where it will lay 


eggs in old poplar borer egg 


scars 


•	 Western popular buprestid 


and other Poecilonota species 


are more narrow than 


Dicerca and Chrysobothris 


species in aspen, and have a 


smooth linear patch running 


from front to back on their 


pronotum; Dicerca species in 


aspen have smooth patches 


on either side of, but not on, 


the centerline
 

References: 1, 3, 9, 10, 14, 37, 54, 52, 55, 56, 59, 58, 63, 91, 95, 98, 101 

Figure 4. Bark removed to show entrance galleries of eastern 

poplar buprestid larvae in cottonwood branches 
65 

 

 

WOOD & BARK BORING INSECTS
 

IRON FLATHEAD 

Poecilonota ferrea (Melsheimer) Coleoptera: Buprestidae 

[=Descarpentriesina ferrea (Melsheimer)] 

Distribution: From southeast BC to QU, south to FL and TX; overlaps with P. 

cyanipes but minimally with P. californica 

Hosts: entatively described as using aspen, willow, or planted willows or poplars 

Identification: Little information is available on 


this species, but it is likely all stages are similar 


to that of other Poecilonota species. Adults are 


very similar to the eastern poplar buprestid (P.
 

cyanipes) but with a more angular pronotum (less 


sinuate at the base), a somewhat shorter elytra 


apex (point) and more hair on the body. Brassy-


greenish elytra often look light gray due to short 


bristle-like hairs (more toward ends) and downy-


like substance stuck in elytra punctures. Visible 


color may range from a dull black to a mottled 


iron gray with a faint tint of brown. Beetles are 


13-20 mm long and 5-8 mm wide. Although not 


described, based on similar species it is likely eggs
 

are small, round, off-white, and laid individually 


in bark crevices, larvae are cream-colored, legless, 


with a shape typical of buprestids, and pupae
 

are creamy white and about the size of an adult 


beetle.
 

Life History: Life history likely similar to that of other Poecilonota species. Flight 

has been noted as occurring June through August (or July through September 

in CA). 

Damage: Has been found mining bark and wood of injured aspen and nuttal 

willow but actual host use is tentative. Tree trunks and large branches may be 

attacked. Exit hole likely to be the 5-8 mm width of adult beetles. Possible that 

little to no frass is ejected if it acts like eastern poplar buprestid (P. cyanipes). 

Similar Damage: Where species’ ranges overlap, type of damage and size of 

galleries may be very similar to other, more common Poecilonota species. Also 

similar is damage by Dicerca, Chrysobothris, and Buprestis species, buprestid 

Figure 1. Iron flathead adult (18 mm) 

WOOD & BARK BORING INSECTS
 

Key: 

• Oval exit holes, probably 5-8 mm wide 

• Fine frass, likely very little is ejected 

• Club-like larvae, with flattened heads and thoraxes 

wood borers of similar size. Adult beetles may be needed to differentiate these 

damage agents. These buprestids leave oval or D-shaped holes slightly smaller 

than the large (~10mm wide), perfectly round holes of the cerambycid, poplar 

borer (Saperda calcarata), or the oval to irregularly shaped, large holes (9-15mm 

wide) of some moth borers (e.g. carpenterworms). Bronze poplar borer (Agrilus 

granulates liragus) is a somewhat smaller buprestid with an oval or D-shaped exit 

hole only 3-4 mm in diameter. 

Remarks: 

•	 This species of Poecilonota considered uncommon; P. cyanipies is more likely 

to be encountered 

References: 9, 14, 54, 55, 91, 98, 101 

64 
67 

 

WOOD & BARK BORING INSECTS
 

POPLAR BORER 

Figure 1. Poplar borer adult 

Saperda calcarata Say Coleoptera: Cerambycidae 

[=Anaerea calcarata Haldeman] 

Distribution: Found throughout most of the U.S. and Canada 

Hosts: Quaking aspen preferred but uses other Populus species and hybrids, 

particularly eastern cottonwood in southern part of range; rarely uses willow 

Identification: Adults are 

moderately robust, elongate, 

longhorned beetles ranging 

from 20-30 mm long; females 

are somewhat stouter than 

males. Body is grayish-blue 

with faint yellow blotches on 

the elytra, all densely stippled 

with fine brown dots. 

Antennae are nearly as long as 

body. Eggs are creamy white 

and 3-4 mm long. Larvae are 

legless, elongate, cylindrical, 

yellowish-white, and up to 40 mm long or larger when mature; shape typcal of 

other cerambycids. Pupae are yellow-white and 20-35 mm long. 

Life History: Adults emerge in summer (May-June in south; July-August in 

north), feeding on foliage and bark from new shoots on host trees. Mating 

begins shortly after emergence. Normally, individual eggs are laid in small 

crescent-shaped holes gnawed in bark by the female. Eggs hatch after two 

weeks and larvae begin feeding just under 

the bark where they spend their first 

winter. Larvae resume feeding in spring, 

enlarging and extending their tunnels 

into tree’s sapwood and heartwood. 

Larvae can take 2-5 years to mature 

with life cycles shorter in the south and 

longer in the north. Throughout their 

developmental period larvae create and 

maintain gallery openings to the outside 

(unlike most other wood borers) through 

which they push coarse boring dust and Figure 2. Poplar borer larva 

WOOD & BARK BORING INSECTS
 

Key: 

• Presence of coarse, fibrous boring material at gallery entrance, in bark crevices, or at base of tree 

• Oozing and reddish, shellac-like staining on bark 

• Split bark, often heavily callused, at gallery entrance 

• Large, round exit holes 

• Honey combed tunnels in sapwood and heartwood 

frass. Pupation occurs in the stem from April to July, depending on location, and 

lasts 2-3 weeks. Adults emerge through a gallery opening. 

Damage: Considered one of the most 

important borers, high tree mortality has 

been attributed to its activity in many 

areas. Wet spots on trunk with oozing 

sap and fine boring dust on trunk are 

earliest signs of poplar borer presence with 

increased amounts of oozing, red sap and 

sawdust appearing as time progresses. 

Although attacks may occur singly, they 

can be clustered with new attacks often 

occurring on previously infested trees. 

Frass—fibrous-like wood shavings mixed 

with excrement—appear as larvae develop. 

Large amounts of this coarse material may 

be seen at tunnel entrances, in bark crevices, 

and in piles around base of infested trees. 

Bark may crack and grow rough calluses 

around openings. Completed galleries, 10­

20 mm diameter, typically extend obliquely 

upward into sapwood for 5-8 cm, then straight 

upward for another 10-18 cm. Galleries are 

often crooked because they intersect or avoid 

galleries of other larvae. Multiple galleries 

create a honey-combed appearance of wood 

within stems. 

Although trees as small as 4 cm diameter 

may be attacked, most infestations occur in 

stems 7-18 cm diameter. Damage is more 

common in open stands or along stand edges 

owing to beetles’ apparent preference for 

ovipositioning on trees exposed to light. Small 

trees are occasionally killed by larvae girdling 

beneath the bark, especially around root 

Figure 3. Frass/boring dust expelled out of 

entrance hole by poplar borer 

Figure 4. Poplar borer gallery exposed 

66 
68 69 

WOOD & BARK BORING INSECTS 

collar or lower stem. Large trees 

may be attacked on any portion 

of the bole and are seldom killed 

outright. However, multiple 

tunnels weaken trees structurally, 

causing them to break in strong 

winds; woodpecker feeding and 

opportunistic decay fungi may 

contribute to this weakening. Egg 

niches and tunnels can provide 

favorable infection courts for 

various pathogens. 

Similar Damage: Other wood 

borers, both cerambycids and 

buprestids, also produce boring 

dust/frass mixtures and may 

cause brown sap flow from 

gallery entrance. However, such 

material produced by other 

species is usually less coarse than 

the shredded wood pieces created 

by poplar borer. Carpenter ants (Camponotus spp.) will produce fine, white 

boring dust while tunneling in holes or cavities made by this or other borers. 

Holes created in wood by this and other cerambycids are round compared to 

oval or D-shaped holes of the buprestids, or oval to irregularly shaped holes of 

moth borers. Holes are large (~10 mm or more in diameter) compared to other 

cerambycids. 

Remarks: 

•	 Active in tree trunks or large branches (if damage noted in root collar or 

main roots of other poplar species, especially in southeast U.S., consider 

Plectrodera scalator [Fabricius]) 

•	 Poplar borer attacks are reported to be heavier in poorly-stocked stands and 

open-grown trees; maintain thick stands until harvest 

•	 Frass characteristics useful for identifying poplar borer include: 

o	 Mostly coarse fibrous or excelsior-like shreds (max 30 mm long by 1 

mm wide but mostly less than 15 mm long) with some finely pulverized 

wood dust 

o	 Excrement pellets constitute less than 40% of ejected frass; intact 

excrement pellets uncommon but would be relatively short (1.5 mm 

long by 1.0 mm wide) 

Figure 5. Multiple galleries and stages of poplar borer 

WOOD & BARK BORING INSECTS 

o	 Frass extruded from holes in 


clumps or ribbon-like pieces, 


separate or loosely clumped; 


silken threads absent; 


yellowish-white to grayish-


white in color 


•	 Cultural practices that promote 


healthy trees are generally 


recommended; trees weakened 


by drought, defoliation, or 


poor growing conditions may 


be preferred although others 


have noted a preference for fast 


growing trees
 

References: 1, 3, 12, 8, 10, 13, 17, 18, 

19, 20, 22, 25, 27, 29, 37, 50, 52, 56, 

58, 59, 78, 81, 84, 87, 88, 90, 91, 95, 

104, 105 

Figure 6. Poplar borer exit hole below the occupied exit 

hole of flatheaded poplar borer 
71 

 

WOOD & BARK BORING INSECTS
 

DUSKY CLEARWING 

(POPLAR TWIG CLEARWING) 

Figure 1. Adult dusky clearwing from U.S. (CO) 

Paranthrene tabaniformis (Rottemburg) Lepidoptera: Sesiidae 

[=Sphinx tabaniformis (Rottemburg); =P. tricincta (Harris) and 

=Aegeria tricincta (Harris) as North American form] 

Distribution: From NL south to FL, west to Rocky Mountain region, northwest 

to AK; also widespread in Europe, North Africa and Asia 

Hosts: In North America, shrubby-form 

willows are preferred in its southern 

range and cottonwoods in its northern 

range; quaking aspen is mentioned 

specifically as a host in association with 

Saperda branch borer galls. In Europe, 

a wide range of Populus are noted 

including European aspen; alder, birch 

and hawthorn are also mentioned but 

not confirmed as hosts in North America 

Identification: Adult moths are bluishblack with yellow bands on various 

abdominal segments (arrangement and 

number depending on subspecies and 

gender) and fuzzy tufts at the posterior end. Additional yellow spots occur on 

the head and legs. Forewings are opaque with reddish brown to violet-black 

tone; hind wings are a bit larger and bordered with dull coppery brown scales. 

Wingspans of males are 24-28 mm; females are slightly larger at 26-32 mm. 

Antennae are comb-like in males but smooth with enlarged end on females. 

Oval eggs are dark brown to dull black and about 0.6-1.0 mm long. Two sides 

are somewhat depressed and the surface has raised polygonal sculpturing. Larvae 

may reach 24-32 mm in length at maturity. Cream colored at maturity, their 

backs are marked with two brown furrows that converge toward the head. Head 

and jointed thoracic legs are yellowish brown, with prominent oval spiracles 

visible on sides of each body segment. The last abdominal segment has two 

brown spines. Pupae are 13-21 mm long, 4-6 mm wide, changing from light to 

dark brown with age, and have spines on the abdomen useful in wriggling to the 

bark surface before emergence. 

Life History: Adults may be active from mid-April to early November, but 

individuals only live 8-10 days on average. Females lay 50-100 eggs on branch 

tips, glued singly to bark, often near damage from previous generations of dusky 

WOOD & BARK BORING INSECTS
 

Key: 

• Swelling visible as symmetrical gall to slight swelling in 1-3 year-old stems, possibly in conjunction 

with damage by other gall forming stem borers, often with stem breakage 

• Round exit hole, maybe 4-5 mm wide, with pupal case partially extruding 

• Black, wasp-like adult moth with opaque, purplish wings, 3-4 abdominal yellow bands, yellow spots 

on head and legs 

clearwing larvae. Newly hatched larvae 

create irregular feeding chambers near 

the oviposition site. More mature 

larvae tunnel into stem pith, ejecting 

frass and debris from the entrance hole 

as galleries are extended and enlarged 

to a final size of about 10 cm in length 

(up to 15 cm). A short gallery that 

extends to just below the bark surface 

is created as the larva nears pupation. 

Larvae overwinter in chambers of silk 

and woody debris, pupating for 2-3 

or more weeks in the spring before 

emerging through a hole in the bark 

surface. The pupal skin is left behind 

at the circular exit hole. 

Damage: Feeding and gallery creation 

causes stem swellings while tunnels 

weaken stems. In young (1 year) 

stems, swelling may create a spherical 

gall. In older trees, swelling may not 

be visible. Large infestations can cause significant growth deformation of 1-3 

year old Populus terminals and branches, most notable in cottonwoods in the 

Southeast. In aspen, it has been found in northern regions using galls created by 

Saperda species where it likely contributes to breakage and death of stems and 

branches. Look for galls on stems and branches, stem breakage, frass expelled 

from entrance holes, and adult exit holes with pupal skins. No size is given for 

the exit hole but similar sized larvae in this genus run 4-5 mm wide which may 

be indicative of the minimum hole diameter that might be expected. Successive 

generations feeding in one location can result in large openings at points of 

infection. European literature also notes feeding in roots but few details are 

given. Life cycle is two years although in some locations in Europe a single year 

is more typical. 

Figure 2. Granular frass ejected from entry hole of larval 

dusky clearwing (from Hungary) 

70 
72 73 

WOOD & BARK BORING INSECTS 

Similar Damage: Association 

with Saperda species can make 

differentiation difficult. However, 

an empty pupal skin will often be 

left behind in the exit hole which 

doesn’t occur with Saperda or Oberea 

beetle borers. No oviposition mark 

is created but use of scars from other 

agents as oviposition sites may make 

it difficult to rule out its presence. 

Swellings caused by poplar twiggall 

fly (Hexomyza schinerie) are initiated 

on current-year growth (although can 

persist in older stems), but do not 

have oviposition scars and may have 

multiple small exit holes (<2 mm 

diameter) after adults have emerged. 

Sesia adults, also clearwing moths, 

are similar in appearance but species 

that use aspen apparently attack larger 

stems and roots. 

Native Paranthrene species P. dolli (Neumoegen) (cottonwood [or poplar] 

clearwing borer) in eastern U.S. and Canada (pushing west to edge of Great 

Plains states), and P. robiniae (Hy. Edwards) (western poplar clearwing) west 

of the Rocky Mountains (pushing east into KS and ND) have similar looking 

adult moths that also attack Populus and Salix host species. Although not noted 

in aspen, they have a wide host range that would suggest aspen should not 

be excluded as a possible host. As such, short descriptions of both species are 

included. 

Adults of P. dolli are reddish, with opaque dark brown forewings (violet or 

coppery reflections) and semitransparent reddish-brown hindwings. Wingspans 

are 30-40 mm. Adults of P. robiniae are yellow and black with opaque orangebrown forewings (veins may be darker) and transparent hindwings with deep 

yellow marks toward the outer edge. Antennae of both species are feathery in 

males and thread-like in females. In both species eggs are brown and oval, 1.0­

1.2 mm long with sculptured surfaces; larvae are whitish, and approximately 

23-32 mm long when mature. Pupae are brown and shiny; 18-20 mm long in 

P. robiniae, 20-25 mm long with two rows of spines in P. dolli. Life cycles are 

generally completed in one year for P. dolli and two years for P. robiniae. 

Figure 3. Larvae of dusky clearwing feeding in stem pith 

(from Hungary) 

WOOD & BARK BORING INSECTS 

Damage by P. dolli can occur anywhere 

on the stem but tend to be around the 

base; stems may be one year or older 

with galls developing on stems less 

than 4 cm in diameter. Trunks and 

larger limbs of young trees are preferred 

by P. robiniae (listed as a trunk/limb 

borer). Entry wounds of both tend to 

ooze brown sap and contain granular 

frass expelled by excavating larvae. 

Larger stems with multiple attacks by 

P. robiniae have multiple entrance and 

exit holes, often expanded over time, 

and can appear galled and cankered. 

Remarks: 

•	 Three subspecies have 


been described across its 


international range P.t. 


tabaniformis (Rottemburg) 


(=P.t. rhingiaeformis), P.t. 


synagiformis (Rambur), and 


P.t. kungessana (Alpheraky); the one described for North America is P.t. 

tabaniformis [=P. tricincta (Harris); =Aegeria tricincta (Harris)]; yellow 

abdominal segment bands for this North American subspecies are on 

segments 2, 4, and 6, also on segment 7 in males 

•	 Management recommendations include 1) maintain tree health and 

minimize damage (including pruning) during moth flight periods that 

might attract adults, 2) remove and destroy infested material - specialists 

suggest containing infested material in mesh with 5x5 mm openings 

that prevent adult moths from escaping but provide opportunities for 

parasitoids, and 3) some biological controls and insecticides have been 

used in Europe 

•	 Desiccation of newly hatched larvae due to dry climate and difficulty 

in entering bark may cause up to 90% mortality 

References: 1, 5, 11, 25, 55, 56, 58, 75, 78, 91, 97 

Figure 4. Pupal case left behind in exit hole when dusky 

clearwing emerged (from Hungary) 
75 

 

WOOD & BARK BORING INSECTS
 

POPLAR BRANCH BORER 

Oberea schaumii LeConte Coleoptera: Cerambycidae 

[=O. papleri Chevrolat] 

Distribution: eastern North America west to BC, CO and TX 

Hosts: Many poplar species are hosts including quaking aspen, bigtoothed aspen, 

Lombardy poplar, Carolina poplar, eastern cottonwood and plains cottonwood; 

eastern cottonwood is preferred in the south with quaking aspen preferred in 

the north 

Identification: Adults are elongate, longhorned beetles 12-16 mm long and 

about 3 mm wide. High variability in coloring has led to descriptions of various 

species or subspecies. Head can vary in color from 

orange to nearly black; prothorax tends to be 

yellowish to orange with 4 dark, smooth spots. 

Elytra coloration ranges from black to brownishyellow to yellow-orange with a covering of short, 

silvery hairs. The underside is often orange. 

Males are mostly black while females account for 

the lighter colors. Eggs are 2.5 mm long, yellowwhite, elongate and occasionally flattened on one 

end. Larvae, 12-25 mm long and yellow-white, 

are roundheaded with dark mandibles, legless, and 

slender with no distinctive taper to the body. Pupae 

are yellow-white. 

Life History: Adults emerge in spring (April-June) and feed on young leaves 

for a few days before females lay eggs in rectangular niches gnawed in young 

branches or stems. Eggs hatch in two weeks, and larvae, after initially boring 

in cambium tissues, move towards the center of the stem and downward. They 

tunnel about 2.5 cm the first year, although larvae expand tunnels throughout 

the lifecycle with completed tunnels up to 30 cm long (17 cm average) and 4 mm 

wide. Initially, frass is ejected through entrance holes, later through secondary 

and tertiary ports (~4mm in diameter) created off the elongated central tunnel. 

Mature larvae eventually tunnel outward to just below the bark, first packing 

granular frass behind them and then fashioning loose plugs of long, fibrous frass 

in the upper part of the tunnel. They pupate behind the frass plug. The adult 

chews through the plug bark to exit. Life cycles are 1-2 years in warmer climates 

and 2-4 (three average) in colder areas. 

Figure 1. Adult poplar branch borer 

WOOD & BARK BORING INSECTS
 

Key: 

• Elongate longhorn beetle 12-16 mm long with 4 black spots on the pronotum 

• Swollen, crooked, or callused branches, especially in the 5-15 mm diameter class 

• Frass protruding from entry and ejection ports (diameter ~4 mm) 

Damage: Old branches or stems 1-6 years and 5-15 mm in diameter are 

preferred, although stems up to 4-5 cm may 

be used. Preference for stands with fewer than 

5,000 suckers per acre are either attractive or 

denser stands are avoided. Long, rectangularshaped egg niches 5-11 mm long and 3 mm 

wide in the bark, usually as two parallel lines 

to the stems axis (top sides of branches), are the 

earliest sign of infestation. With time these look 

more like two parallel splits in the bark. Later 

signs of infestation include swollen or crooked 

branches and stems, and frass protruding from 

entrance and ejection ports. Callus tissue that 

develops around exterior openings gives stem a 

swollen appearance. Breakage is uncommon but 

happens when there are multiple tunnels in the 

stem. Poplar branch borer does not normally 

cause serious loss. However, up to a third of 

canker fungi in aspen have been associated with 

this borer. Woodpeckers excavating for beetle 

larvae may cause additional damage. 

Similar Damage: Saperda inornata (poplar-gall Saperda) and S. populnea moesta 

(poplar gall borer) also create swellings in young stems, often larger and more 

gall-like. Adults of these Saperda species are smaller (generally <12 mm), more 

uniformly gray, and do not have four spots on the prothorax; their egg niches are 

horseshoe shaped, and larvae do not construct secondary and tertiary ports for 

frass extraction. Their final galleries are usually shorter (up to 2.5 cm and largely 

within the gall). Swellings caused by poplar twiggall fly (Hexomyza schineri) are 

created on smaller twigs but can grow larger as the tree grows around them 

making differentiation harder; no egg niche scars are created and exit holes are 

smaller (<2 mm diameter). 

Remarks: 

•	 Avoid confusion with the similar species name O. schaumii Garnett 

(different author) now called O. quadricallosa LeConte or “western 

poplar branch borer”. This species uses poplars and willows west of the 

Rocky Mountains (including Vancouver Island), although aspen does 

not appear to be a recorded host. Adults are similar in coloration and 

Figure 2. Woodpecker holes in poplar 

branch borer infested stem 

74 
77 

 

WOOD & BARK BORING INSECTS
 

Figure 3. Possible entrance hole (A) and gallery (B) of poplar branch borer 

size (8-14 mm long) but are separated by O. quadricallosa having more 

grayish brown elytra with only a narrow basal band of yellow, head 

and scutellum are always black, and the basal spots on the pronotum 

are larger. Also avoid confusion with O. schaumi Linsley & Chemsak 

(one “i” and different author) which has been renamed in part as O. 

pruinosa Casey and part as O. caseyi Plavilstshikov, both found in 

eastern North America; O. pruinosa on 

Populus deltoides. 

•	 The “poplar twig borer”, O. delongi
 

Knull, also attacks Populus species but 


in not noted in aspen and is found in 


northeastern U.S.; similar in size to O. 


schaumii and O. quadricallosa at 7-14 mm 


long, O. delongi differs in 1) four spots 


on the pronotum lacking, 2) coloration 


mostly black with some yellow along 


outer margin of elytra; head, prothorax, 


and underside of body can range from 


yellowish to black, 3) legs yellow, and 4) 


may use smaller material [if 1.2-5.0 cm 


diameter look for O.schaumii; if less than 


1.2 mm look for O.delongi] 

•	 Frass characteristics of O. schuamii and 

O. delongii described as pale yellow to 

light brown with excrement pellets <40% of frass ejected and rarely 

intact; primarily finely pulverized wood, some fibrous or excelsior-like 

shreds, usually extruded in tight clumps; silken threads absent; gallery 

entrance usually plugged (sometimes tightly) with frass 

•	 In plantation or nursery settings, removal and destruction of infested 

branches or stems, or use of insecticides intended for wood borers can 

reduce infestation levels; natural controls (parasites, woodpeckers, 

unidentified diseases) destroy up to 98% of some populations) 

References: 1, 3, 10, 17, 18, 37, 42, 44, 51, 56, 58, 59, 67, 72, 78, 80, 90, 91 

Figure 4. Adult Oberea quadricallosa 

(top) and O. delongi (bottom) 

WOOD & BARK BORING INSECTS
 

POPLAR GALL SAPERDA 

(WILLOW GALL SAPERDA) 

Saperda inornata (Say) Coleoptera: Cerambycidae 

[=S. concolor LeConte; =S. concolor unicolor Felt & Joutel; =S. mecasoides Casey] 

Distribution: From northern MB and SK, east to southern ON and QU, south 

to CO, AZ, TX to southern IL; in its Southeast range (AZ, NM, TX), much of 

the literature on S. inornata is under S. concolor LeConte (willow gall saperda) 

Hosts: Several species in Populus and Salix 

(willow) are hosts; willow appears to be a 

preferred host in some areas with quaking aspen 

favored in north central U.S.; susceptibility of 

quaking aspen to damage varies by clone 

Identification: Adults are 8-13 mm long, 

black, longhorn beetles, covered with dense 

hairs which makes them appear dark gray. 

Antennae also have hairs and are slightly 

shorter than the body. Eggs are creamy white, 

elongate, sometimes flattened on one end and 

2.5 mm long. In early summer horseshoeshaped egg niches are visible, often in a ring 

around the stem. Mature larvae are 10-16 mm 

long, white, slender and smooth or shiny with 

sparse white hairs. Pupae are shaped like adults, white and 8-13 mm long. 

Life History: Adults emerge in early summer (mid-May to July) and feed on 

edges of leaves or leaf midribs, and on outer tissues of new shoots or twigs. 

Female beetles cut a horseshoe- or shield-shaped slit in the soft bark (3mm wide 

with open end up) into which one egg is laid. Usually 2-3 but up to nine of 

these oviposition sites may be created in a ring around the stem. Eggs hatch in 

12-15 days with young larvae feeding in necrotic tissue that develops around the 

oviposition site. 

As larvae mature, feeding creates flat, irregular galleries, extending in one 

direction around the stem; reaching halfway around on large stems, further 

on smaller stems. Galleries are kept clean with frass ejected from holes gnawed 

near the oviposition site. In response to oviposition and feeding damage, the 

tree creates callous tissue resulting in a gall; look for these as early as late June. 

Toward end of the first summer, larvae bore a round or oval hole into the center 

Figure 1. Adult poplar gall saperda (on a 

hybrid poplar leaf) 

76 
78 79 

WOOD & BARK BORING INSECTS 

Key: 

•	 Dark gray beetle, without spots, 8-13mm long 

•	 Shield or horseshoe-shaped scar where eggs laid 

•	 Spherical, scabby galls on 5-15mm diameter stems and branches; callous tissue present where feeding 

has occurred just under bark, bark sometimes sloughing off to expose black feeding scars 

•	 Broken branch stubs at a gall or dead branches above a gall, with larval gallery 2-4 cm long running 

lengthwise up and down center of stem 

•	 White larvae or pupae in woody tissue inside gall; galls with one 3-4 mm diameter exit hole gnawed 

in the side will be empty 

of stem, then upward or downward along the 

stem’s axis. This central gallery is expanded as 

larvae develop but appears to reach about 2.5 

cm long in aspen (2-4 cm); lengths of over 11 

cm have been noted in willow. 

Before pupating and overwintering, larvae pack 

their feeding gallery and the first 1/3 of their 

central gallery with frass. At the far end of their 

central gallery, larvae chew a portion of their 

future exit tunnel. High mortality of early stage 

larvae result in few (often one) larvae pupating 

and overwintering in a gall, each in their own, 

non-intersecting gallery. Adults emerge from 

a 3-4 mm round to oval shaped hole bored in 

the side of the gall. Life cycles last 1-3 years 

depending on climate and timing of oviposition 

with one year more common in the south and 

two years in the north. 

Damage: Suckers (3-15 mm in diameter) and 1-3 to 5 year old trees are most 

susceptible, although stems 5 cm in diameter or larger may be used. As young 

larvae begin feeding in the phloem, the aspen forms callus tissue around the site 

creating a warty or scabby globose or spindle-like gall up to twice stem diameter, 

sometimes more swollen along one side. Oviposition scars are U-shaped, visible 

for several years as the 

outer bark sloughs off 

creating dark brown, 

half-moon shaped scabby 

patches. Stems and 

branches sometimes die 

or break off at the gall; 

if not, tree can overgrow 

the gall. Galls also can 

Figure 2. U- or shield-shaped oviposition 

scar made by poplar gall saperda 

Figure 3. Poplar gall saperda adult, larva and gallery 

WOOD & BARK BORING INSECTS 

often provide an entry point for Hypoxylon 

canker (Entoleuca mammata), Cytospora (Valsa 

sordida Nitschke [= Cytospora chrysosperma 

(pers.) Fr.]), and other canker fungi. Girdling 

of the main stem or branches results in lost 

growth, although trees can recover height 

growth in 2-3 years. Damage to young trees 

can reduce overall reproduction levels in wellstocked stands. However, attacks rarely result 

in significant mortality. 

Similar Damage: Gall-like or callus swellings 

created by Saperda populnea are very similar 

but may be smoother looking. Poplar branch 

borer (Oberea schaumii) caused swellings are 

less gall-like, egg niches are elongate rectangles 

rather than U-shaped, several additional 

holes created to eject frass may be present, 

and feeding is more parallel to the stem with a longer (>2.5 cm) central tunnel 

when completed. Swellings caused by poplar twiggall fly (Hexomyza schineri) are 

generally on smaller, current-growth stems with several small holes; however, old 

galls may enlarge as tree grows. In addition, no egg oviposition scars are present. 

Remarks 

•	 In nurseries management techniques include maintaining vigorous 

stands, sanitation through removing and destroying infested branches 

and trees, and chemical; older stands rarely need treatment 

•	 S. inornata attacks increased with stand density up to 3500 stems per 

acre then leveled off (no decreased attacks with increased density as 

with O. schaumii) 

•	 Eastern poplar buprestid (Poecilonota cyanipes) and dusky clearwing 

(Paranthrene tabaniformis) may use stem galls formed by S. inornata 

•	 S. inornata Say is not synonymous with Mecas inornata Townsend (now 

M. confusa Chemsak & Lindsley) or M. inornata Packard (now M. 

cana saturnine [LeConte]); as far as is currently known, Mecas species 

do not make galls 

References: 1, 3, 10, 18, 20, 37, 43, 44, 45, 58, 66, 67, 72, 78, 91, 102 

Figure 4. Gall-like swellings from poplar gall 

saperda 
81 

 

WOOD & BARK BORING INSECTS
 

SMALL POPLAR BORER 

 (POPLAR GALL BORER) 

Saperda populnea (L.) Coleoptera: Cerambycidae 

Three subspecies are recognized by some: 

S. p. moesta LeConte EASTERN GALL SAPERDA 

S. p. populnea (L.) 

S. p. tulari Felt & Joutel WESTERN GALL SAPERDA 

Distribution: Of the three subspecies, only S.p. moesta and S.p. tulari are listed 

as being in the West with the first ranging across southern Canada and northern 

U.S. from the east coast to the Rocky Mountains, and the latter ranging along 

the West Coast from BC south into CA, east to AZ 

Hosts: All subspecies are noted as attacking Populus species but only S.p. moesta 

has been noted specifically in aspen with balsam poplar as the principal host; 

S.p. tulari is mentioned from black 

cottonwood specifically 

Identification: Adults are blackbodied, slender longhorned beetles 9.5 

mm long and 2.7 mm wide. Adults 

appear gray colored due to uniform 

gray (S.p. moesta) to reddish gray (S.p. 

tulari) hairs, mostly concentrated in 

patches on each side of the pronotum. 

Each tapered, rounded elytra has 4-5 round punctures filled with golden-yellow 

hair although these golden dots are not obvious on the male (per European 

literature). Female antennae are shorter than the body; male antennae are longer. 

Prothorax is not spined but two yellow bands may be visible along the sides. Eggs 

are oval, approximately 2.4mm long and 0.7mm wide, with a curved middle and 

somewhat pointed end. Mature larvae are 11 mm long, legless, smooth, shiny 

cream-yellow, with some fine long whitish hairs. Heads are small and reddish 

brown in front, pale behind, with a pale streak along the top running front to 

back. Pale yellow pupae (12.5 mm long) have a few short spines on back side of 

the abdomen. 

Life History: Adults emerge from round exit holes about 3 mm in diameter in 

early summer to mid-summer. After feeding on foliage and tender bark of twigs, 

females deposit eggs (about 50) singly in slits cut in the bark. Larvae initially 

mine under the bark around the twig; later, they bore into the wood, forming 

short (~3cm) frass-packed galleries parallel to the twig axis. Larvae overwinter 

Figure 1. Small poplar borer adult 

WOOD & BARK BORING INSECTS 

in the gall. Its one-year 

life cycle is completed 

when larvae pupate the 

following spring. 

Damage: Galls are found 

mostly on twigs, branches, 

or stems three years or 

younger, but can occur on 

trees of any age; in Europe 

and Asia, young main 

stems are preferred with 

97% of attacks found on 

stems 5-11 mm diameter. 

Adults like open forest 

or forest edges so trees 

in these conditions and 

branches in upper crowns 

are more susceptible. 

U-shaped oviposition 

scars, and gall-like or callus 

swellings are the most 

easily detected indicators 

of infestation. Galls are 

smooth and spindleshaped in appearance, 

slightly flattened, and ~30 

mm long and up to 19 mm 

wide. Formation of the gall 

can alter the oviposition 

scar from U-shaped to a 

narrow slit at an oblique angle. Galleries (up to 25 mm long) are mostly filled 

with yellowish-orange frass. Exit holes are circular with a diameter of 2.4-4.2 

mm. Branches that become weakened at swelling points can break during high 

winds. Trees survive since infections are localized, although significant, repeated 

attacks can stunt growth or cause mortality of young stems. Hypoxylon canker 

(Entoleuca mammata) is often established in the infected twigs. 

Similar Damage: Similar gall-like or callus swellings appear on poplar gall 

Saperda (S. inornata) infected stems and branches but small poplar borer galls 

may look smoother. Unlike S. inornata, small poplar borer larval activity is 

confined within the gall and stem breakage is more likely due to the generally 

smaller stems it infests. Poplar branch borer (Oberea schaumii) produces stem 

swellings that are not as gall-like and may have several exit ports (about 4 

Figure 2. Small poplar borer larvae typically located in twigs, small 

branches or young stems 

80 
83 

 

 

 

WOOD & BARK BORING INSECTS
 

Key: 

• Smooth, spindle-shaped galls or callus swellings on new twigs, small branches or young stems. 

• U-shaped oviposition scars that may change to a narrow slit at an oblique angle as gall swells 

• All boring activity confined within the gall; galleries up to 25 mm long mostly filled with yellowish 

orange frass 

• Circular exit holes 2.4-4.2 mm in diameter 

mm diameter) used for frass removal; oviposition scars are rectangular versus 

U-shaped. Swellings caused by poplar twiggall fly (Hexomyza schineri) are created 

on smaller twigs but can grow larger as the tree grows around them making 

differentiation harder; no egg niche scars are created and multiple small holes 

(<2 mm diameter) are probable. 

Figure 3. Smooth ovoid swellings of small poplar borer showing oviposition scars (left and center) and exit hole (right) 

(examples from Europe) 

Remarks: 

•	 Several fungi have been used with success as biological control agents 

against small poplar borer for localized outbreaks in high value stands 

in Europe and Asia 

References: 10, 11, 25, 37, 56, 58, 59, 91, 102 

WOOD & BARK BORING INSECTS
 

POPLAR TWIGGALL FLY 

Hexomyza schineri (Giraud) Diptera: Agromyzidae 

[=Agromyza schineri Giraud; =Melanagromyza schineri (Giraud)] 

Distribution: Noted in the Rocky Mountain and Midwest regions of the U.S. 

with possible expanding range 

Hosts: Best known for 

serious galling on quaking 

aspen but will also use some 

other Populus species 

Identification: Adults are 

stout-bodied, shiny dark 

flies, about 2-3 mm long. 

Eggs are not described 

but are injected into the 

stem. Larvae are small, 

pale yellow-green maggots 

found within galls. Pupae 

are greenish with a darkened 

head area and 2-3 mm in 

length like adults. 

Life History: Poplar twiggall fly overwinters within a gall as a mature, yellowgreen maggot. Pupation occurs in late winter or early spring. Most pupae work 

their way out of galls in March and early April, and drop to the ground leaving 

small round exit holes less than 2 mm wide. Some pupae, however, may remain 

in the gall. As new shoot 

and branch growth 

is starting in spring, 

adult flies emerge and 

become active. During 

daylight hours, they 

can be found sunning 

themselves on leaves. 

After mating, females 

move to developing 

twigs and insert eggs into 

stems. After maggots 

hatch, and in response 

Figure 1. Adult poplar twiggall fly 

Figure 2. Poplar twiggall fly larva exposed on gall 

82 
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WOOD & BARK BORING INSECTS
 

Key: 

• Smooth knot-like gall on twigs of aspen 

• Small, green-yellow maggots inside of gall or small holes in older galls 

to their feeding 

activity, distinctive 

twig swellings 

begin. At first, 

swelling involves 

a fairly indistinct 

enlargement. 

However, within 

two months a 

full-size gall is 

usually present. 

Developing 

maggots grow 

slowly within galls 

during summer, 

and are difficult to find until late summer when growth becomes more rapid. 

Soon, 1-3 larvae will fill a small cavity (gall) within swollen area of twig. In early 

spring, larvae tunnel towards the surface of the gall leaving a thin flap of bark 

(operculum) covering the tunnel. Pupae work out through a small hole in the 

gall, falling to the ground. Adults later emerge coincident with the development 

of new growth. There is typically one generation per year, but unusually warm 

seasons may produce a second generation. 

Damage: Poplar twiggall flies produce smooth, spherical gall swellings (average 

13 mm long and 8.5 mm wide) on current-season, elongating twigs. Areas 

below buds appear to be favored sites for galls and there may be multiple galls 

on one twig. These 

galls remain in place 

and continue to grow 

and enlarge even after 

maggots are gone. 

Galls persist, become 

incorporated into 

growing twigs and 

branches, ultimately 

resulting in large 

swollen bands on 

trunks and branches 

that produce a gnarled 

Figure 3. Early swelling symptom of poplar twiggall fly and adult leaf damage 

Figure 4. Branch nodes are preferred oviposition sites for poplar twiggall fly 

WOOD & BARK BORING INSECTS 

and knobby appearance. 

While bud growth adjacent 

to galls is inhibited, 

galls do not appear to 

significantly weaken 

plants. Occasionally, 

Cytospora canker may 

develop around a gall, 

likely using the exit hole 

wound for entry. 

Similar Damage: Poplar 

gall saperda (Saperda 

inornata), poplar gall borer 

(S. populnea), and poplar 

branch borer (Oberea 

schaumii) also cause galls 

on young stems. However, branches they select are slightly larger, oviposition 

scars are often visible, and exit holes are larger. 

Remarks: 

•	 Some genetic variation in resistance by trees to twiggall fly is apparent 

•	 One of the few species of Agromyzidae leaf miners that do not mine 

leaves; although it forms galls it is not a true gall midge 

•	 A small wasp, Eurytoma contractura, parasitizes and commonly kills 

large numbers of poplar twiggall fly maggots; predation of pupae by 

chickadees and other birds also occurs 

•	 Control with chemical has had poor results, as has trapping 

•	 Has become a common pest of ornamental trees in some areas 

References: 13, 18, 20, 21, 

30, 54, 55, 58, 95 

Figure 5. Pupae of poplar twiggall fly emerging from galls 

Figure 6. Old twiggall fly injury incorporated into new wood as tree 

grows 

84 
 

 

WOOD & BARK BORING INSECTS
 

WILLOW SHOOT SAWFLY 

Janus abbreviatus (Say) Hymenoptera: Cephidae 

Distribution: Considered an eastern species it ranges across southern Canada 

from NB to AB; in east and central U.S. from ME to MN and SD, south to VA, 

AR and MS; however, also was noted in OR 

Hosts: Preferred host is black willow with quaking aspen rare except perhaps 

MN; other recorded hosts include other willows, eastern cottonwood, balsam 

and black poplar, and bigtooth aspen 

Figure 1. Willow shoot sawfly larvae and frass in central tunnel of young stem 

Identifi cation: Adults are delicate, wasp-like sawflies 7-10 mm long and brown 

in color. Translucent wings span 10-12 mm in males and 12-16 mm in females. 

Head and thorax are glossy black with small white to yellow markings. Female 

abdomens are black with body segments 2-3 (sometimes 4) red to reddish brown; 

in males, only the underside is colored. Female abdomens are flattened vertically 

and have a sharp saw-like ovipositor (looks like a stinger). Eggs are translucent 

to whitish, oval to elongate, and 0.8-1.0 mm long and 0.3-0.5 mm wide. Larvae 

are white, except for pale yellow head, brownish mandibles, and a short, round, 

brown prong at the tip of the abdomen. Cylindrical larvae are normally S-shaped 

and 8-11 mm long when fully grown. Thoracic legs are short, fleshy, without 

claws, and abdominal prolegs typical of sawfl ies are absent. Pupae are 8-10 mm 

long, white initially but darkening with maturity, and enclosed in a brownish, 

partially transparent cocoon. 

Life History: Flight of willow shoot sawfly varies with the number of generations; 

the first flight likely timed with the period of shoot elongation in its host trees. 

WOOD & BARK BORING INSECTS
 

Key: 

• Wilted terminal or lateral leaders with a ring of small punctures ringing the tender shoot 

• Dead or stunted stems with hollow, frass filled tunnels and round 1.5-2.5 mm diameter exit holes 

• Whitish, S-shaped larvae or brownish, partly-transparent cocoons within tunnels 

The female girdles new shoots with a series of 

5-16 punctures made with its ovipositor. She 

then lays one or two eggs in additional punctures 

made below the girdle. The shoot wilts quickly 

in response to the circle of punctures and within 

a few days leaves will turn black. Upon hatching 

the larva tunnels and feeds toward the girdle for 

a few millimeters, then turns downward and 

tunnels for 7-10 cm - often the entire length of 

the shoot. As it feeds, frass is packed into older 

parts of the tunnel. Each tunnel is occupied by 

a single larva. When fully grown, larvae chew a 

short passage into the wall of the tunnel toward 

the outer bark, leaving intact a thin layer of 

bark to hide the opening. This point will later 

become the adult sawfly’s exit hole. Prior to 

emerging from 

the 1.5-2.5 mm 

diameter hole, 

the thin layer of 

bark may appear 

as a dark, round 

circle. Within 

the tunnel, 

larvae construct a thin, slightly membranous 

cocoon in which they overwinter. They 

pupate and emerge as adults in spring or early 

summer. There is one generation per year in the 

northern range with up to three generations in 

southeastern states. 

Damage: The earliest evidence of injury is a 

wilting and shepherd’s crook-like drooping 

of terminals above the circle of oviposition 

punctures. Larvae tunneling will also kill the 

remaining branch tip. Winds can snap the 

weakened shoots. Bush-like growth often occurs 

below dead shoot tips. 

Figure 2. The spiral girdling of a stem by 

a willow shoot sawfly with frass packed in 

the tunnel 

Figure 3. Round exit hole of willow shoot 

sawfly 

86 87 
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WOOD & BARK BORING INSECTS 

Similar Damage: The shepherd’s 


crook-like wilting separates this 


borer from others that attack small 


shoots and branches. Larvae of 


willow shoot sawfly also have prolegs 


that are lacking in larvae of other 


insects creating similar damage. The 


fungus Venturia macularis (Fr.) E. 


Mull & Arx (shepherd’s crook) may 


create similar wilting but without 


signs of perforations or boring in the 


stem.
 

Remarks: 

•	 Natural mortality is 

high due to fall/winter 

desiccation (especially 

in smaller, less vigorous 

shoots), and to natural 

parasitoids 

•	 Management is limited 

although removal and 

destruction of infested 

branches can lower population levels 

References: 1, 2, 3, 10, 13, 17, 25, 58, 78, 91, 93, 95 

Figure 4. Willow shoot sawfly can cause shoot dieback that 

takes on a shepherd’s crook appearance 

WOOD & BARK BORING INSECTS
 

[AN ASPEN BARK BEETLE] 

Procryphalus mucronatus (LeConte)	 Coleoptera: Scolytidae 

Distribution: From AK to east NV, MT, ID, CO and NM 

Hosts: Only known from quaking aspen 

Identification: Adult beetles are dark brown to black and about 2.2 mm long 

(1.8-2.2 mm) with identifying features visible under a microscope. Eggs are 

approximately 0.4 mm wide and 0.7 mm long, translucent white ovals with a 

sticky surface. Cream-colored larvae are legless. Pupae are likely cream colored 

and the size of adult beetles. 

Life History: 

The female P. 

mucronatus 

initiates gallery 

construction 

and is soon 

joined by a male 

who will work 

to maintain 

sole access to 

her. Following 

gallery construction and mating a series of eggs are deposited along the gallery 

walls – perhaps no more than 14 eggs total. After a period of more than three 

weeks new larvae begin feeding on phloem tissues in both the main gallery and 

galleries they excavate into dead phloem tissue. Larval development time is about 

60 days or longer when overwintering; P. mucronatus can overwinter as larvae, 

pupae, or pre-emergent adults. With this asynchronous life cycle, emerging 

adults may begin attacks as early as late April that continue through summer. 

Likely 1.5 to 2 generations are produced annually. 

Damage: Procryphalus mucronatus is found on dead, often fermenting, bark of 

stressed or dying quaking aspen. The attack accelerates decomposition of the 

dead parts of the tree without accelerating tree death itself. Sunny sides of tree 

boles and larger limbs may be preferred, the increased heat possibly accelerating 

beetle development and phloem decomposition. 

Galleries have entrance holes nearly perpendicular to bark surface that tend 

to become plugged with frass as beetles extend their tunnels. Egg galleries 

Figure 1: Adult Procryphalus mucronatus beetle and close-up of antennal club 

88 
91 

 

WOOD & BARK BORING INSECTS
 

Key: 

• Entrance holes on dead bark 0.8–1.0 mm in diameter and perpendicular to bark surface; may be 

plugged with frass 

• Galleries somewhat deep into the bark, up to 7 mm from bark surface 

• Oxidized tissue dark but not black on larval gallery walls 

• Bark above galleries not normally cracked 

• Sunny sides of tree boles and larger limbs preferred 

Figure 2. Procryphalus mucronatus galleries in 

bark of weakened aspen tree 

are 1-3 mm wide and around 14 mm long 

and look more tunnel- than cave-like. They 

may be straight or crooked, branched or 

un-branched, trend upward, are largely free 

of frass and are not stained black. Eggs are 

laid randomly along tunnel walls with larvae 

feeding in and widening this main gallery. 

Short tunnels created by older larvae often 

end in a pupal chamber 0.25 mm wide. Bark 

above these tunnels does not usually crack 

after beetle emergence. 

Similar Damage: Trypophloeus populi 

(Hopkins) and T. thacheri (Wood) are two 

other small bark beetles attacking quaking 

aspen in the West. Trypophloeus populi differs 

from P. mucronatus in its later emergence and attack date, its use of healthier 

trees and live bark, its shallower, wider egg galleries with black-stained larval 

tunnels, clustered egg deposition, and tendency of bark to split over gallery areas. 

Little is known about T. thacheri although its biology is likely similar. These 

species of beetles are difficult to differentiate in the field due to their small size, 

but can be distinguished with the use of a microscope (see remarks below). 

Remarks: 

•	 Morphological differences between T. populi and P. mucronatus include 

(respectively): 5 versus 4 segmented antennae funnicle; pointed-oval 

versus elongate-oval antennal club; 3 straight antennal club sutures 

versus 2-3 procurved sutures (the 1st septate); pronotum with setae 

over entire surface versus anterior portion only; also P. mucronatus’s 

pronotum has a distinct raised line (rounded) on basal and lateral 

margins. 

References: 46, 54, 64, 65, 82, 86, 103, 104 

WOOD & BARK BORING INSECTS
 

[AN ASPEN BARK BEETLE] 

Trypophloeus populi Hopkins	 Coleoptera: Scolytidae 

Distribution: Samples identified from MT, ID, UT, CO, NV, AZ, SK, MB, 

and NB 

Hosts: Also found in lanceleaf, narrowleaf, and black cottonwoods 

Identification: Trypophloeus populi adults are dark brown to black beetles 

between 1.7 and 2.1 mm in length, small enough to require a microscope 

for species identification. Eggs laid under bark are translucent white colored, 

oblong, approximately 0.3 mm wide and 0.6 mm long with slightly sticky 

surfaces. Larvae are legless and initially white, turning brownish after feeding 

on the dark phloem. Pupae are likely cream colored and the size of adult beetles. 

Figure 1: Adult Trypophloeus populi beetle (left) and close-up of antennal club (right) 

Life History: Attack is initiated by the female beetle, usually in July. Males are 

quickly attracted to these attacks suggesting existence of pheromones in the mass 

attack process. Females are often watched over by a single male who prevents 

entry of rival males and possibly predators to the cave-like main egg gallery. 

Females lay 10-25 eggs, most in a single cluster, within this gallery, although 

smaller groups or individual eggs may be laid on other parts of this irregularly 

shaped chamber. In approximately three weeks eggs begin to hatch. Larvae 

feed outward into unused phloem, overwintering as larvae before pupating the 

following spring. Adults emerge during mid-summer and into fall. In some cases 

1.5 generations may be completed in a year; larva is still the most common 

overwintering stage. 

90 
92 93 

WOOD & BARK BORING INSECTS 

Key: 

•	 Entry holes 0.8–1.0 mm diameter on live, smooth green bark, especially of stems 30-50 cm in 

diameter 

•	 Oddly shaped, cave-like, shallow galleries just under bark surrounded by areas of lightly brown-stained 

bark about 2–4 cm in diameter 

•	 Black staining on walls of larval galleries 

•	 Cracked bark above galleries, numerous exit holes, and browning leaves later in the season 

Damage: Attacks are made in smooth, 

green bark of standing trees and 

can hasten decline and mortality of 

stressed trees; occasionally broken 

limbs may be used. Stands of 30-50 cm 

diameter trees, especially those infected 

with Ganoderma root and butt rot 

(Ganoderma applanatum [Pers.] Pat.), 

have shown high incidence of attack, 

although smaller material may be 

used. Unhealthy or diseased trees are 

preferred. Shortly after attack, infested 

trees show signs of smaller leaf size and 

yellowish coloring; 3-10 weeks later 

crowns turn brown. In addition to 

multiple 0.8-1.0 mm wide entrance/ 

exit holes, 2-4 cm diameter bark 

patches may turn light brown, often 

cracking above the primary gallery as 

it desiccates. 

Attacked trees are often infested over all suitable bole and branch surfaces. 

Entrance galleries angle inward and upward, running about 2.5 mm in length, 

and ending in a primary egg chamber where most eggs are laid. The female 

may then create a feeding gallery approximately 1 cm long, frass packed, and 

radiating out from the main chamber. At the gallery end she may excavate a 

secondary chamber where she lays more eggs, dies and/or exits. Larval galleries 

26-42 mm long radiate from where eggs were laid. These galleries are packed 

with dark frass and stained brownish-black with a symbiotic fungi. In later stages 

the necrosis associated with the gallery often results in dense patches of dead 

cambium. 

Similar Damage:Procryphalus mucronatus is another very small bark beetle attacking 

quaking aspen in the West. However, P. mucronatus tends to feed on already-dead 

bark patches, sometimes attacking trees several weeks after T. populi. Procryphalus 

mucronatus can overwinter as pupae or adult as well as larvae, and emerges earlier. 

Figure 2: Entrance and exit holes of Trypophloeus populi 

WOOD & BARK BORING INSECTS
 

Figure 3: Galleries of Trypophloeus populi 

Galleries of P. mucronatus are further below the bark surface with individual eggs 

laid apart from each other rather than in cluster. Bark over P. mucronatus galleries 

does not split, and staining along galleries is not as apparent. 

Three additional species of Trypophleous are identified in North America, two 

that attack elms and willow and another, T. thatcheri (Wood) recorded from 

quaking aspen and black cottonwood. Adult beetles of T. thatcheri are also black 

but slightly smaller (1.5-1.9 mm) and distributed from BC to CA; biology is 

likely same as T. populi. These species of beetles are difficult to differentiate 

in the field due to their small size, but can be distinguished with the use of a 

microscope (see remarks below). 

Remarks: 

•	 Morphological differences between T. populi and P. mucronatus include 

(respectively): 5 versus 4 segmented antennae funnicle; elongated, 

pointed oval versus more circular, flattened oval antennal club; 3 

straight antennal club sutures versus 2-3 procurved sutures (the 

1st septate); pronotum with setae over entire surface versus anterior 

portion only; also P. mucronatus’s pronotum has a distinct raised line 

(rounded) on basal and lateral margins 

•	 T. populi was associated with the 2005-2009 sudden aspen decline in 

CO and UT 

References: 54, 64, 65, 82, 86, 103, 104 
95 

 

 

 

WOOD & BARK BORING INSECTS
 

POPLAR AMBROSIA BEETLE 

Trypodendron retusum (LeConte) Coleoptera: Scolytidae 

Distribution: From AK to NB, south through CA, NM and WV 

Other Hosts: Quaking aspen, bigtooth aspen and eastern cottonwood; may 

attack paper birch but doesn’t reproduce in it 

Identification: Adult poplar ambrosia 


beetles are 3.6-4.6 mm long and stubby 


looking. Coloration is uniformly shiny 


dark brown to black when mature but 


when young, elytra may appear light brown 


with pale yellowish-brown patches running 


front to back through the center of each 


wing cover. Curved, white, legless larvae
 

are 3.6-5.0 mm long. Eggs and pupae are 


not described but are likely white or cream 


colored, with pupae the size of adult beetles.
 

Life History: Female beetles initiate attack 

with mating taking place either on the bark surface or at tunnel entrance. 

Initially, female excavates a main tunnel 2.6-5.5 cm into the sapwood. She then 

angles off to make a peripheral, horizontal gallery following a sapwood ring; 

2-5 (average of 3) such peripheral galleries are constructed. Toward the end of 

these peripheral tunnels 2-7 very short, horizontal galleries (cradles) are created 

(up and down within the sapwood ring). A single egg is oviposited in a cradle 

and surrounded with boring material. Beetles are monogamous with the female 

excavating tunnels and the male near the entrance hole removing boring dust 

and frass. Females also inoculate tunnels with ambrosia fungus from a special 

gland (mycangia). Gallery systems are usually created and used by one pair of 

beetles; if additional mated pairs are present they use separate gallery branches. 

Larvae hatch within a week, feeding on fungus and enlarging cradles until they 

are slightly bigger than the size of an adult beetle. After 3-4 weeks pupation 

occurs and lasts for just over a week. In mid-summer (July) new adults collect 

fungus spores and emerge from the tunnels. By early fall, adults move to forest 

litter to overwinter. Overwintered beetles emerge and become active again in 

early spring. A one-year life cycle is typical. 

Figure 1. Young poplar ambrosia beetle 

WOOD & BARK BORING INSECTS
 

Key: 

• Fine texture boring dust and frass – off-white - on bark around small entrance holes or at base of 

tree; usually origination from dead or nearly dead wood 

• Small horizontal galleries and vertical chambers surrounded by a dark brown or black stain 

Figure 2. Entry hole of poplar 

ambrosia beetle in recently killed stem 

Figure 3. Poplar ambrosia beetle’s stained, horizontal 

tunnel with secondary lateral chambers (cradles) 

Damage: Poplar ambrosia beetles are attracted 

to dying or newly dead aspen snags, stumps 

and logs so are not important in causing tree 

mortality. Ambrosia beetle larvae feed exclusively 

on symbiotic fungi (e.g. Ambrosiella ferruginea 

[L.R. Batra]) introduced by the female. The fungus 

produces a dark brown or black stain which lines 

the tunnels. 

Similar Damage: The small, round dark brown or 

black stained tunnels that run several centimeters 

deep into sapwood are unique. Adult aspen bark 

beetles (Procryphalus and Trypophloeus species) are 

significantly smaller beetles that feed in bark and 

phloem rather than sapwood. 

Remarks: 

• Ptilinus basalis LeConte also 

uses dead wood of aspen and other 

hardwoods. Adults are 3.0-5.5 mm 

long, chestnut brown with short 

yellowish hairs, cylindrical in shape. 

Males are smaller than females and 

have comb-like rather than serrated 

antennae. Found from BC to CA, 

into UT. It uses dead and cured 

wood, damaging stored hardwoods 

used for crafts, furniture, siding, etc. 

•At least one species of Anobiidae has been 

found using dead, dry quaking aspen. The 

female creates a short tunnel, lays eggs, then 

dies, plugging the entrance hole with her 

abdomen sticking out. The larvae hatch, 

excavating long, winding, frass packed 

tunnels. Symbiotic microbs help generate 

nutrients needed to survive. 

References: 7, 37, 46, 91, 98, 103 Figure 4. Ptilinus basalis male adult 

94 
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WOOD & BARK BORING INSECTS
 

EPIDERMAL BARK-MINING INSECTS 

[a bark-mining fly] Diptera: Agromyzidae 

possibly Phytobia sp. 

[bark-feeding micro-moths] Lepidoptera:Tortricidae/Olethreutidae 

Cydia populana (Busck)

 [=Laspeyresia populana Busck] 

Marmata spp. 

Although not of economic significance, several forms of unidentified bark feeding 

and mining have been noted. Most common is a spider-like bark etching, but 

feeding just under the bark with frass visible has also been found. The agent 

responsible for the spider-like mining has not been identified but may be a fly 

species; Phytobia is one genus with species that feed under bark in the cambium 

of trees. Cydia populana has been noted as feeding on aspen bark but the damage 

has not been described. The following are details on some of the damages found 

and possible species responsible. 

Figure 1: Close-up of superficial damage of 

an epidermal bark-mining insect (fresh top left, 

recently dried bottom left, and old scars right) 

WOOD & BARK BORING INSECTS
 

Key: 

• Superficial etching into bark surface 

• Fine frass not associated with wood borers or bark beetles 

Figure 2: Unidentified bark feeding by a small moth 

on a green tree in MT (two to right); and unidentified 

bark feeder from a different green tree in MT (two at 

bottom) 

Phytobia species 

Distribution and Host: The spider-like etching noted on aspen possibly due to a 

small fly such as Phytobia has been found in WA, MT, NV, UT, CO, WY and 

AZ, and is likely in other areas; other hosts unknown. 

Life History: Around 15 or so species of Phytobia are recognized in North 

America. Adults are a small (3-4.5 mm long, likely), mostly black fly with short 

antennae and covered with bristly hairs. Larvae are white, legless, headless and 

soft with a pair of hook-like mouthparts; many species are 20-25 mm long (15­

30 mm range) and approximately 1 mm in diameter. The anterior spiracle is very 

characteristic for the family. 

96 
98 99 

 

WOOD & BARK BORING INSECTS
 

Figure 3: Adult fly likely of Phytobia genus 

(above); larvae likely of Phytobia genus 

showing characteristic anterior spiracle of the 

Agromyzidae family (three to right side) 

Cydia populana 

Distribution and Host: Cydia populana has been described from MT, CO and 

AB on aspen and black cottonwood, but sightings (photographs) exist for other 

locations in western U.S as well as northern areas of central and eastern U.S. 

In Canada sightings include southern portions of western, central and eastern 

Canada. 

Life History: Adult moths of Cydia populana are described as having blackish 

brown forewings with brownish-yellow (ocher) markings spanning 13-14 mm 

and light brownish-gray colored hind wings with white cilia. The body is a 

dark brownish-gray with a light, brownish-yellow underside. No information is 

available on life history or immature life stages, nor on damage done. 

WOOD & BARK BORING INSECTS 

Marmata species 

Distribution and Host: Bark mining micro-moths also exist within the genus 

Marmata. Species have been described as mining in smooth bark of ash trees, as 

well as other hardwoods and conifers in the U.S. No species has been identified 

as feeding on quaking aspen although aspen seems a plausible host. Many species 

in this genus have not been described, making identifications difficult; many 

species are leaf miners. 

Life History: From Marmata species currently described, the small adult moths 

of this genus have fringed wings spanning approximately 6.5-8.5 mm with black 

and white designs, and bodies about 2.5-3.5 mm long. Live adults of one species 

are described as having a “tripod” stance with the body held at a 30-45o

 angle, 

first pair of legs together in front with the end of the abdomen touching the 

ground. Eggs may be flattened, oval, with a glassy, iridescent cover. Larvae of 

some species have been described as cream colored when feeding, turning to 

orange or red when they mature to web-spinning stages. Pupae may darken from 

yellow to pale brown. 

Damage: 

•	 The spider-shaped mining by the possible fly species is superficial and 

does not appear to affect the tree, not even as an infection court for 

pathogens 

•	 No description of the damage done by Cydia populana has been found; 

some species within this genus damage cones and branch tips 

•	 No description of the damage done by Marmata species is readily 

available 

Similar damage: The spider-like etchings of the bark fly appear unique but it 

is unknown if more than one species is responsible. It is possible some types of 

bark feeding may have superficial resemblance to mild roughbark diseases. 

References: 4, 6, 15, 16, 32, 33, 34, 37, 62, 75, 76, 85, 91, 94, 100 

Figure 4: Adult moths of Cydia populana at rest (left) and with wings spread (right) 
100 101 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WOOD & BARK BORING INSECTS 

Index - Agent Scientific Names 

SPECIES NAME CORRECTION ORDER FAMILY 

Acossus centerensis (Lintner) 

Acossus populi (Walker) 

Aegeria tibialis pacifica (Hy. Edwards) 

Agrilus acastus Kerremans 

Agrilus blanchardi Horn 

Agrilus granulatus (Say) 

Agrilus granulatus liragus Barter & Brown 

Agrilus horni Kerremans 

Agrilus liragus Barter & Brown 

Agromyza schineri Giraud 

Anaerea calcarata Haldeman 

Buprestis confluenta Say 

Buprestis femorata Olivier 

Buprestis lesnei Garnett 

Buprestis tesselata Casey 

Buprestis viridisuturalis Nicolay & Weiss 

Camponotus species 

Chrysobothris femorata (Olivier) 

Chrysobothris mali Horn 

Cryptorhynchus lapathi (L.) 

Cydia populana (Busck) 

Descarpentriesina californica (Chamberlin) 

Descarpentriesina cyanipes (Say) 

Descarpentriesina ferrea (Melsheimer) 

Dicerca callosa Casey 

Dicerca callosa callosa Casey 

Dicerca callosa frosti Nelson 

Dicerca divaricata (Say) 

Dicerca frosti Nelson 

Dicerca longipennis Casey 

Dicerca pertinax Casey 

Dicerca prolongata LeConte 

Dicerca rigida Casey 

Dicerca severa Casey 

Dicerca subargentea Casey 

Dicerca subcuprea Casey 

Dicerca sulcatula Casey 

Dicerca tenebrica (Kirby) 

Dicerca tetrica Casey 

Hexomyza schineri (Giraud) 

Janas abbreviatus (Say) 

Laspeyresia populana Busck 

see: Sesia tibialus (Harris) 

see: Agrilus horni Kerremans 

see: Agrilus horni Kerremans 

see: Agrilus granulatus liragus B.&B. 

see: Agrilus granulatus liragus B.&B. 

see: Hexomyza schineri (Giraud) 

see: Saperda calcarata Say 

see: Chrysobothris femorata (Olivier) 

see: Buprestis viridisuturalis N.&W. 

see: Buprestis confluenta Say 

Lepidoptera Cossidae 

Lepidoptera Cossidae 

Lepidoptera Sesiidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Diptera Agromyzidae 

Coleoptera Cerambycidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Hymenoptera Formicidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Curculionidae 

Lepidoptera Tortricidae / 

Olethreutidae 

see: Poecilonota californica (Chamberlin) Coleoptera Buprestidae 

see: Poecilonota cyanipes (Say) Coleoptera Buprestidae 

see: Poecilonota ferrea (Melsheimer) Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

see: Dicerca callosa Casey Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca callosa Casey Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

see: Dicerca tenebrica (Kirby) Coleoptera Buprestidae 

Coleoptera Buprestidae 

see: Dicerca callosa Casey	 Coleoptera Buprestidae 

Diptera Agromyzidae 

Hymenoptera Cephidae 

see: Cydia populana (Busck) Lepidoptera Tortricidae / 

Olethreutidae 

WOOD & BARK BORING INSECTS 

SPECIES NAME CORRECTION ORDER FAMILY 

Marmata species
 

Mecas cana saturnine (LeConte)
 

Mecas confusa Chemsak & Lindsley
 

Mecas inornata Packard
 

Mecas inornata Townsend
 

Melanagromyza schineri (Giraud)
 

Oberea delongi Knull
 

Oberea papleri Chevrolat
 

Oberea quadricallosa LeConte
 

Oberea schaumi Linsley & Chemsak 


Oberea schaumii Garnett 


Oberea schaumii LeConte
 

Paranthrene dolli (Neumoegen)
 

Paranthrene robiniae (Hy. Edwards) 


Paranthrene tabaniformis (Rottemburg)
 

Paranthrene tabaniformis
 

kungessana (Alpheraky) 

Paranthrene tabaniformis 

synagiformis (Rambur) 

Paranthrene tabaniformis 

tabaniformis (Rottemburg) 

Paranthrene tricincta (Harris) 

Phytobia species 

Poecilonota californica (Chamberlin) 

Poecilonota cyanipes (Say) 

Poecilonota ferrea (Melsheimer) 

Prionoxystus robiniae (Peck) 

Procryphalus mucronatus (LeConte) 

Ptilinus basalis LeConte 

Saperda calcarata Say 

Saperda concolor LeConte

Saperda concolor unicolor Felt & Joutel

Saperda inornata (Say) 

Saperda mecasoides Casey

Saperda populnea (L.) 

Saperda populnea moesta LeConte 

Saperda populnea populnea (L.) 

Saperda populnea tulari Felt & Joutel 

Sesia apiformis (Clerck) 

Sesia tibiale (Harris)

Sesia tibialis (Harris) 

Sphinx tabaniformis (Rottemburg)

Sternochetus lapathi (Linnaeus)

Sthenopis purpurascens (Packard) 

Sthenopis quadriguttatus (Grote)

Lepidopters Tortricidae / 

Olethreutidae 

Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

see: Mecas cana saturnine (LeConte) Coleoptera Cerambycidae 

see: Mecas confusa Chemsak & Lindsley Coleoptera Cerambycidae 

see: Hexomyza schineri (Giraud) Diptera Agromyzidae 

Coleoptera Cerambycidae 

see: Oberea schaumii LeConte Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

(now part O. pruinosa Casey and Coleoptera Cerambycidae 

part O. caseyi Plavilstshikov) 

see: Oberea quadricallosa LeConte Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

Lepidoptera Sesiidae 

Lepidoptera Sesiidae 

Lepidoptera Sesiidae 

see: Paranthrene tabaniformis (R.) Lepidoptera Sesiidae 

see: Paranthrene tabaniformis (R.) Lepidoptera Sesiidae 

see: Paranthrene tabaniformis (R.) Lepidoptera Sesiidae 

see: Paranthrene tabaniformis (R.) Lepidoptera Sesiidae 

Diptera Agromyzidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Coleoptera Buprestidae 

Lepidoptera Cossidae 

Coleoptera Scolytidae 

Coleoptera Anobiidae 

Coleoptera Cerambycidae 

see: Saperda inornata (Say) Coleoptera Cerambycidae 

see: Saperda inornata (Say) Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

see: Saperda inornata (Say) Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

Coleoptera Cerambycidae 

Lepidoptera Sesiidae 

see: Sesia tibialis (Harris) Lepidoptera Sesiidae 

Lepidoptera Sesiidae 

see: Paranthrene tabaniformis (R.) Lepidoptera Sesiidae 

see: Cryptorhynchus lapathi (Linnaeus) Coleoptera Curculionidae 

Lepidoptera Hepialidae 

see: Sthenopis purpurascens (Packard) Lepidoptera Hepialidae 
102 103 

 

 

 

 

 

 

 

WOOD & BARK BORING INSECTS WOOD & BARK BORING INSECTS 

SPECIES NAME CORRECTION ORDER FAMILY Index - Agent Common Names Trypodendron retusum (LeConte) 

Trypophloeus populi Hopkins 

Trypophloeus thatcheri (Wood) 

Xylotrechus annosus (Say) 

Xylotrechus mormonus Hopping

Xylotrechus mormonus (LeConte) 

Xylotrechus obliteratus LeConte 

Coleoptera 

Coleoptera 

Coleoptera 

Coleoptera 

see: Xylotrechus bowditchi hoppingi Linsley Coleoptera 

(in X. annosus write-up) 

Coleoptera 

Coleoptera 

Scolytidae 

Scolytidae COMMON NAME SCIENTIFIC NAME PAGE 

Scolytidae American hornet moth* 

Cerambycidae aspen carpenter wormo 

Cerambycidae aspen root girdler 

(blue footed poplar buprestid) 

Cerambycidae bronze poplar borer*o 

Cerambycidae carpenter ant 

carpenterworm*o 

cottonwood clearwing borer 

cottonwood crown borero 

dusky clearwing 

(eastern gall saperda) 

eastern poplar buprestid 

flatheaded appletree borer*o 

flatheaded poplar borero 

four spotted ghost moth 

gold dust buprestid 

hornet moth* 

iron flathead 

Pacific flatheaded borer* 

poplar ambrosia beetleo 

poplar-and-willow borer*o 

poplar borer*o 

poplar branch borero 

poplar-butt borer 

poplar butt borero 

poplar carpenter wormo 

(poplar dicerca) 

(poplar gall borer) 

poplar gall saperda 

(poplar ghost moth) 

poplar twig borer 

(poplar twig clearwing) 

poplar twiggall fly* 

small poplar borer 

western gall saperda 

western poplar branch borer 

western poplar buprestid 

western poplar clearwing* 

(willow gall saperda) 

willow shoot sawfly*o 

(yellow spotted jewel beetle) 

Sesia tibialis (Harris) 19
 

Acossus populi (Walker) 35
 

Agrilus horni Kerremans 25
 

Poecilonota cyanipes (Say) 61
 

Agrilus granulatus liragus Barter & Brown 41
 

Camponotus species 30
 

Prionoxystus robiniae (Peck) 37
 

Paranthrene dolli (Neumoegen) 72
 

Sesia tibialis (Harris) 19
 

Paranthrene tabaniformis (Rottemburg) 70
 

Saperda populnea moesta LeConte 80
 

Poecilonota cyanipes (Say) 61
 

Chrysobothris femorata (Olivier) 47
 

Dicerca tenebrica (Kirby) 57
 

Sthenopis purpurascens (Packard) 23
 

Buprestis confluenta Say 45
 

Sesia apiformis (Clerck) 22
 

Poecilonota ferrea (Melsheimer) 64
 

Chrysobothris mali Horn 50
 

Trypodendron retusum (LeConte) 94
 

Cryptorhynchus lapathi (Linnaeus) 52
 

Saperda calcarata Say 66
 

Oberea schaumii LeConte 74
 

Xylotrechus obliteratus LeConte 27
 

Xylotrechus mormonus (LeConte) 28
 

Acossus centerensis (Lintner) 33
 

Dicerca tenebrica (Kirby) 57
 

Saperda populnea (L.) 80
 

Saperda inornata (Say) 77
 

Sthenopis purpurascens (Packard) 23
 

Oberea delongi Knull 76
 

Paranthrene tabaniformis (Rottemburg) 70
 

Hexomyza schineri (Giraud) 83
 

Saperda populnea (L.) 80
 

Saperda populnea tulari Felt & Joutel 80
 

Oberea quadricallosa LeConte 75
 

Poecilonota californica (Chamberlin) 59
 

Paranthrene robiniae (Hy. Edwards) 72
 

Saperda inornata (Say) 77
 

Janus abbreviatus (Say) 86
 

Buprestis confluenta Say 45
 

*common name approved by Entomological Society of America (accessed 15 May, 2014) 

0 common name approved by Entomological Society of Canada (accessed 15 May, 2014) 

(-) secondary common name given in this guide 
104 105 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WOOD & BARK BORING INSECTS 

List of Tree Common and 

Scientific Names 

COMMON NAME SCIENTIFIC NAME 

alder 

apple 

ash 

ash, green 

aspen 

aspen, bigtooth 

aspen, European 

aspen, quaking / trembling 

birch 

birch, paper 

cottonwood 

cottonwood, black 

cottonwood, eastern 

cottonwood, Fremont 

cottonwood, lanceleaf 

cottonwood, narrowleaf 

cottonwood, plains 

cottonwood, Rio Grande 

elm 

hawthorn 

locust 

locust, black 

maple 

box elder 

oak 

poplar 

poplar, balsam 

poplar, Carolina
 

poplar, black
 

poplar, Lombardy
 

poplar, Russian
 

sycamore 

willow 

willow, black 

willow, nuttall / Scouler’s 

Alnus Mill. 

Malus Mill. 

Fraxinus L. 

Fraxinus pennsylvanica Marshall 

Populus L. 

Populus grandidentata Michx. 

Populus tremula L. 

Populus tremuloides Michx. 

Betula L. 

Betula papyrifera Marshall 

Betula papyrifera Marshall var papyrifera 

Populus L. 

Populus balsamifera L. ssp. trichocarpa 

(Torr. & A. Gray ex Hook.) Brayshaw 

Populus deltoides W. Bartram ex Marshall 

Populus deltoides W. Bartram ex Marshall ssp. deltoides 

Populus fremontii S. Watson 

Populus fremontii S. Watson ssp. Fremontii 

Populus fremontii S. Watson ssp. mesetae Eckenwalder 

Populus ×acuminata Rydb. [from angustifolia x deltoides] 

Populus angustifolia James 

Populus deltoides W. Bartram ex Marshall ssp. 

monilifera (Aiton) Eckenwalder
 

Populus deltoides W. Bartram ex Marshall ssp. 


wislizeni (S.Watson) Eckenwalder 

Ulmus L. 

Crataegus L. 

Robinia L. 

Robinia pseudoacacia L. 

Acer L. 

Acer negundo L. 

Quercus L. 

Populus L. 

Populus balsamifera L.
 

Populus balsamifera L. ssp. balsamifera
 

Populus ×canadensis Moench [from P. deltoides x P. nigra]
 

Populus nigra L.
 

Populus nigra L.
 

Populus ×petrowskiana R.I. Schrod. ex Regel
 

Platanus L. 

Salix L. 

Salix nigra Marshall 

Salix scouleriana Barratt ex Hook 

WOOD & BARK BORING INSECTS
 

References 

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2.	 Bates, P.C.; Blinn, C.R.; Alm, A.A.; Perala, D.A. 1989. Aspen stand development following harvest 

in the Lake States region. Northern Journal of Applied Forestry 6(4): 178-183. 

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Report NC-1. North Cent. Exp. Stn., St. Paul, MN. Pages 83-87 Online: http://www.treesearch.fs.fed.us/ 

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Betula pendula. International Association of Wood Anatomists (IAWA) Journal 22(3): 289-294. 

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Online: http://insects.ummz.lsa.umich.edu/mes/gle-pdfs/vol21no1.pdf#page=8. 

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10.	 Burns, R.M.; Hokala, B.H. 1990. Silvics of North America: 2. Hardwoods. Agriculture Handbook 654, 

Volume 2. Washington, DC: USDA Forest Service. 877 p. Online: http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/populus/tremuloides.htm. 

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Natural Resource Canada, Canadian Forestry Service, Northern Forestry Centre. Online: https://tidcf.nrcan. 

gc.ca/. 

13.	 Center for Invasive Species and Ecosystem Health, University of Georgia. 2013 (accessed). Bugwood. [Online]. Athens, GA: University of Georgia. Online: http://www.bugwood.org/. 

14.	 Chamberlin, W. J. 1922. A review of the genus Poecilonota as found in America north of Mexico (Coleoptera, family Buprestidae) with descriptions of new species. Journal of the New York Entomological Society 

30(1):52-66. 

15.	 Chisholm, M.D.; Reed, D.W.; Underhill, E.W.; Palamiswamy, P.; Wong, J.W. 1985. Attraction of tortricid moths of subfamily Olethreutinae to field traps baited with dodecadienes. Journal of Chemical 

Ecology 11(2): 217-230. 

16.	 Colorado State University. 2012 (accessed). Common insects and diseases of aspen. [Online]. Fort 

Collins, CO: Colorado State University, Cooperative Extention. Online: http://csfs.colostate.edu/pages/insectdiseases-aspen.html. 

17.	 Coyle, D.R.; Nebeker, T.E.; Hart, E.R.; Mattson, W.J. 2005. Biology and management of insect 

pests in North American intensively managed hardwood forest systems. Annual Review of Entomology 50: 

1-29. 

18.	 Cranshaw, W. 2004. Garden insects of North America: the ultimate guide to backyard bugs. Princeton, NY: 

Princeton University Press. 656 p. 
106 107 

 

WOOD & BARK BORING INSECTS 

REF# 	 CITATION 

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75.	 North American Moth Photographers Group. 2013 (accessed). Digital Guide to Moth Identification. 

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77.	 Oregon State University. 2008 (last modified). Poplar and willow borer. Corvallis, OR: Oregon State 

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78.	 Ostry, M.E.; Wilson, L.F.; McNabb, H.S.; Moore, L.M. 1989. A guide to insect, disease, and 

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cottonwood. Annals of the Entomological Society of America 17(4): 654-657. 
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REF# 	 CITATION 

94.	 Steed, B.E.; Kearns, H.S.J. 2009. Damage agents and condition of mature aspen stands in Montana 

and northern Idaho. Numbered Report 10-03. Missoula, MT: USDA Forest Service, Forest Health Protection. 26 

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95.	 Stein, J.D.; Kennedy, P.C. 1972. Key to Shelterbelt insects in the Northern Great Plains. Research Paper 

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102. Wong, H.R.; McLoed, B.B.; Melvin, J.C.E. 1966. Life histories of Saperda concolor Lec. and Saperda 

populnea moesta LeC. in Manitoba and Saskatchewan (Coleoptera: Cerambycidae). Internal Report MS-34. 

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gc.ca/pubwarehouse/pdfs/23333.pdf. 

103. Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae), 

a taxonomic monograph. Great Basin Naturalist Memoirs, Number 6. Bringham Young University, Provo, UT. 

1359 p. 

104. Worrall J.J.; Egeland, L.; Eager, T.; Mask, R.A.; Johnson, E.W.; Kemp, P.A.; Shepperd, 

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North Dakota State University Extension Service. 52 p. Online: http://library.ndsu.edu/repository/ 

handle/10365/5261. 

WOOD & BARK BORING INSECTS
 

Figure Credits
 

Agent section Figure# Image Credit 

INTRODUCTION 1 USGS digital representation of aspen range as found in Little Jr, E. L. 1971. 

Atlas of United States trees. Volume 1. Conifers and important hardwoods. 

Miscellaneous publication 1146. USDA Forest Service, Washington, DC. 

2 Brytten Steed, USDA Forest Service 

3 Brytten Steed, USDA Forest Service 

INDIVIDUAL DAMAGE AGENTS 

root, root crown, lower stem 

Lepidoptera (moths) 

American hornet moth 1 © Mike Mclvor (from North American Moth Photographers Group) 

2 Tom DeGomez, Associate Agent, Agriculture and Natural Resources, 

AZ Cooperative Extension, University of Arizona 

3 Tom DeGomez, Associate Agent, Agriculture and Natural Resources, 

AZ Cooperative Extension, University of Arizona 

4 © V. Marius Aurelian (BugGuide.net) 

four-spotted ghost moth 1a&b © Jason J. Dombroskie (from North American Moth Photographers Group) 

2a&b © G.G. Anweiler, Museums and Collections Services, University of Alberta, 

E.H. Strickland Entomological Museum, accessed 2014 

(http://entomology.museums.ualberta.ca/index.html) 

Coleoptera (beetles) 

aspen root girdler	 1 © Robert L. Otto (BugGuide.net) 

2 Mike Ostry, USDA Forest Service, Bugwood.org 

3 Mike Ostry, USDA Forest Service, Bugwood.org 

poplar butt borer 1 L.G. Bezark, L.G. A photographic catalog of the Cerambycidae of the World. 

Available from: https://apps2.cdfa.ca.gov/publicApps/plant/bycidDB/ 

wdefault.asp (accessed 28 January 2014) 

2 © Jeff Gruber, University of Wisconsin Entomology Depart. (BugGuide.net) 

3a-c Brytten Steed, USDA Forest Service 

4 Brytten Steed, USDA Forest Service 

carpenter ants	 1 Jim Baker, North Carolina State University, Bugwood.org 

2 Whitney Cranshaw, Colorado State University, Bugwood.org 

3 Brytten Steed, USDA Forest Service 

4 Brytten Steed, USDA Forest Service 

5 Joseph O'Brien, USDA Forest Service, Bugwood.org 

trunk and large branches 

Lepidoptera (moths/butterflies) 

poplar carpenter worm 1 James Solomon, USDA Forest Service, Bugwood.org 

2 © Cindy Mead (BugGuide.net) 

aspen carpenter worm 1a&b © Tom Dimock (from North American Moth Photographers Group) 

2 © John Davis 

carpenterworm	 1 James Solomon, USDA Forest Service, Bugwood.org 

2 James Solomon, USDA Forest Service, Bugwood.org 

3a James Solomon, USDA Forest Service, Bugwood.org 

3b Whitney Cranshaw, Colorado State University, Bugwood.org 

4 Bob Hammon, Colorado State University, Bugwood.org 

5 James Solomon, USDA Forest Service, Bugwood.org 
112 113 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WOOD & BARK BORING INSECTS 

AGENT SECTION FIGURE#	 IMAGE CREDIT 

Coleoptera (beetles) 

bronze poplar borer 1 

2 

3a&b 

4a 

4b 

gold-dust buprestid 1a 

1b 

2a 

2b&c 

flathead appletree borer	 1 

2 

3 

Pacific flathead borer	 1 

2 

3 

poplar and willow borer 1 

2 

3 

4 

5 

6 

Dicerca callosa 1 

2 

flathead poplar borer 1 

2 

western poplar buprestid 1a 

1b 

eastern poplar buprestid 1 

2 

3 

4 

iron flatheaded borer 1 

Brytten Steed, USDA Forest Service 

Mike Ostry, USDA Forest Service, Bugwood.org 

Tom Zegler, USDA Forest Service 

Tom Zegler, USDA Forest Service 

James Solomon, USDA Forest Service, Bugwood.org 

Steven Valley, Oregon Department of Agriculture, Bugwood.org 

© Carol Davis (BugGuide.net; licensed under a Creative Commons License 

at http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

© JenJohn (BugGuide.net; licensed under a Creative Commons License at 

http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

Steven Valley, Oregon Department of Agriculture, Bugwood.org 

Joseph Berger, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

© Tom Murray (BugGuide.net; licensed under a Creative Commons License 

at http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

James Solomon, USDA Forest Service, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Fabio Stergulc, Università di Udine, Bugwood.org 

Bill Zanze, Portland OR parks 

© G.J. Hilchie, Museums and Collections Services, University of Alberta, 

E.H. Strickland Entomological Museum, accessed 2014 

(http://entomology.museums.ualberta.ca/index.html) 

© G.J. Hilchie, Museums and Collections Services, University of Alberta, 

E.H. Strickland Entomological Museum, accessed 2014 

(http://entomology.museums.ualberta.ca/index.html) 

Brytten Steed, USDA Forest Service 

Brytten Steed, USDA Forest Service 

© Joshua P. Basham (Bugguide.net) 

© Dennis Haines (Bugguide.net) 

© Mike Quinn (BugGuide.net; licensed under a Creative Commons License 

at http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

James Solomon, USDA Forest Service, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

© Tim Loh (BugGuide.net) 

WOOD & BARK BORING INSECTS 

AGENT SECTION FIGURE# 	 IMAGE CREDIT 

poplar borer	 1 

2 

3 

4 

5 

6 

small branches and twigs 

Lepidoptera (moths/butterflies) 

dusky clearwing 1 

2 

3 

4 

Coleoptera (beetles) 

poplar branch borer	 1 

2 

3a 

4a 

4b 

poplar gall saperda	 1 

2 

3 

4 

small poplar borer 1 

Tom Zegler, USDA Forest Service 

Natural Resources Canada, Canadian Forest Service, accessed Feb. 2014 

(http://tidcf.nrcan.gc.ca/en/home) 

Tom Zegler, USDA Forest Service 

Lindsey Myers, USDA Forest Service 

James Solomon, USDA Forest Service, Bugwood.org 

Brytten Steed, USDA Forest Service 

© DianeWilson (BugGuide.net; licensed under a Creative Commons License 

at http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

James Solomon, USDA Forest Service, Bugwood.org 

Brytten Steed, USDA Forest Service 

S. Heydon, accessed through L.G. Bezark. A photographic 

catalog of the Cerambycidae of the World. Available from: 

https://apps2.cdfa.ca.gov/publicApps/plant/bycidDB/wdefault.asp 

(accessed January 2014) 

© Andy Daun (BugGuide.net; licensed under a Creative Commons License at 

http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

© Stephen Luk (BugGuide.net; licensed under a Creative Commons License 

at http://creativecommons.org/licenses/by-nd-nc/1.0/ and 

http://creativecommons.org/licenses/by-nd-nc/1.0/legalcode) 

Mike Ostry, USDA Forest Service, Bugwood.org 

Mike Ostry, USDA Forest Service, Bugwood.org 

Mike Ostry, USDA Forest Service, Bugwood.org 

© Joyce Gross (joycegross.com; Bugguide.net) 

2a&b Natural Resources Canada, Canadian Forest Service, accessed Feb. 2014 

(http://tidcf.nrcan.gc.ca/en/home) 

2c Petr Kapitola, State Phytosanitary Administration, Bugwood.org 

3a-c Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org 

Diptera (flies) 

poplar twiggall fly 1 Whitney Cranshaw, Colorado State University, Bugwood.org 

2 Whitney Cranshaw, Colorado State University, Bugwood.org 

3 Whitney Cranshaw, Colorado State University, Bugwood.org 

4 Whitney Cranshaw, Colorado State University, Bugwood.org 

5 Whitney Cranshaw, Colorado State University, Bugwood.org 

6 Whitney Cranshaw, Colorado State University, Bugwood.org 
114 115 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WOOD & BARK BORING INSECTS 

AGENT SECTION FIGURE#	 IMAGE CREDIT 

Hymenoptera (sawflies, wasps, ants) 

willow shoot sawfly 1 James Solomon, USDA Forest Service, Bugwood.org 

2 James Solomon, USDA Forest Service, Bugwood.org 

3 James Solomon, USDA Forest Service, Bugwood.org 

4 James Solomon, USDA Forest Service, Bugwood.org 

bark beetles and other bark insects - trunk or branches 

Coleoptera (beetles) 

Procryphalus mucronatus 1a&b Mercado, J.E. 2010. Bark Beetle Genera of the United States. Colorado State

 Univ., USDA-APHIS-PPQ Center for Plant Health Science and Technology, 

and USDA-FS Rocky Mountain Research Station. January 2014. 

2 Brytten Steed, USDA Forest Service 

Trypophloeus populi 1a&b Mercado, J.E. 2010. Bark Beetle Genera of the United States. Colorado State

 Univ., USDA-APHIS-PPQ Center for Plant Health Science and Technology, 

and USDA-FS Rocky Mountain Research Station. January 2014. 

2 Brytten Steed, USDA Forest Service 

3a&b Brytten Steed, USDA Forest Service 

poplar ambrosia beetle	 1 Steven Valley, Oregon Department of Agriculture, Bugwood.org 

2 Brytten Steed, USDA Forest Service 

3 Tom Zegler, USDA Forest Service 

4 © M.S. Caterino/SBMNH (BugGuide.net) 

Epidermal bark-mining insects 

1a&b Tom Zegler, USDA Forest Service 

1c Brytten Steed, USDA Forest Service 

2a-d Lindsey Myers, USDA Forest Service 

3a © Bo Zaremba (BugGuide.net) 

3b-d © Pierre-Marc Brousseau (BugGuide.net) 

4a © Nolie Schneider (from North American Moth Photographers Group) 

4b Jerry Powell, Essig Museum of Entomology 

(CalPhoto and North American Moth Photographers Group) 

USDA is an equal opportunity provider and employer. To file a complaint of discrimination, write: USDA, 

Office of the Assistant Secretary for Civil Rights, Office of Adjudication, 1400 Independence Ave., SW, 

Washington, DC 20250-9410 or call (866) 632-9992 (Toll-free Customer Service), (800) 877-8339 

(Local or Federal relay), (866) 377-8642 (Relay voice users). 

Dedication
 

This work is dedicated to David A. Burton without whom this 

work, and many other aspen-related projects, would not have 

been possible. His dedication to this guide, his entrepreneurial 

spirit, and his love of aspen made him invaluable. His friendship 

made him irreplaceable. 

David A. Burton 

1943-2014