gypsy moth - university of maryland...the gypsy moth is native to most of temperate europe, asia and...

Gypsy MothLymantria dispar Linnaeus (Lepidoptera: Lymantriidae)

Male (left) and female gypsy moth adults. USDA APHIS PPQ, Bugwood.org

INTRODUCTION:The Gypsy Moth (GM) is an exotic, invasive insect introduced near Boston, MA, in 1869 by a French naturalist, Etienne Leopold Trouvelot, who hoped to breed them for silk production. Some moths escaped, and with hundreds of host plant species available for larvae to feed on, the pest rapidly increased in numbers. By 1890, the state and federal governments joined forces in an attempt to eradicate the now serious infestation. Although the effort eventually failed, it set the precedent for cooperative control efforts of alien pests in this country. GM is now established as one of the most devastating pests of hardwood trees in the U.S., defoliating an average of nearly a million acres annually, and more than 88 million acres total since 1924. Every year new GM infestations are detected and control protocols enacted, making it the target of more eradication and control strategies than any other forest insect in U.S. history.

GM has no native enemies in this country, and with its prolific reproductive rate and voracious appetite it causes enormous damage to natural and urban forests and the economy. Infestations can alter wildlife habitats and affect the quality of life in communities that suffer repeated outbreaks. Economic losses caused by GM have averaged $30 million a year for the last 20 years, according to USDA estimates. Efforts at containing and slowing the spread (STS) of GM cost the USDA Forest Service over $13 million in 2006 alone. In the past decade there has been an overall decline in the number of GM defoliated acres due to naturally occurring disease, STS and eradication efforts nationwide. However, in the last few years populations have begun to rise again.

Most of the GM in North America are of European origin, but in recent years the Asian Gypsy Moth (AGM) has been accidentally introduced through international shipping. AGM feed on nearly twice as many host plants as GM, including conifers, and AGM females are capable of flight. These two traits make AGM a greater threat to North American forests than GM. The two strains of gypsy moths appear to interbreed freely, leading to concerns that females of the resulting offspring might also be capable of flight. Considerable resources have been applied to detecting and eradicating new infestations of AGM.

DISTRIBUTION/SPREAD:The Gypsy Moth is native to most of temperate Europe, Asia and North Africa, where it is considered a significant pest. In North America, it is established in 19 eastern states and the District of Columbia in the U.S. (CT, DC, DE, IL, IN, ME, MD, MA, MI, NC, NH, NJ, NY, OH, PA, RI, VT, VA, WI, WV), and in four Canadian provinces (southern Ontario, southern Québec, southwestern New Brunswick and southwestern Nova Scotia). Sporadic infestations of GM have been detected and eradicated in a number of western states (including Idaho, Utah, Oregon, Washington, and California) almost annually since 1974. Currently, GM infests less than 30% of its susceptible hosts in the U.S.

Adult male GM spread naturally by flight, but females cannot fly. Newly hatched larvae disperse naturally by hanging down on silken threads to catch a breeze and “balloon” short distances, usually less than ½ mile (0.80 km) although occasionally much further. Artificial or long range dispersal occurs when humans accidentally transport GM egg masses (and occasionally larvae and adults) from infested areas on vehicles, firewood, camping equipment, and other outdoor items, into uninfested areas. Research reported in 2008 determined the average rate of expansion in generally infested zones (defined as 10 moths captured per trap line) to be nearly 13 miles/year (20.8 km/year).

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UMD Entomology Bulletin, 2008

EXOTIC PEST THREATS

Gypsy Moth, Lymantria dispar Linnaeus

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HOST PLANTS:GM larvae are polyphagous but prefer to feed on the foliage of hardwoods, especially oaks and aspen. GM populations are greatest where oaks are the most plentiful trees, but if oaks are not available, they will feed on several hundred different species of trees and shrubs. Older larvae will feed on hosts often avoided by younger larvae (cottonwood, hemlock, southern white cedar, and pines and spruces native to the East), and when populations are very high, larvae of all stages will feed on almost any vegetation. In addition to oak and aspen species, other common hosts include: alder, apple, basswood, beech, birch, boxelder, cherry, cottonwood, hawthorn, linden, maple, poplar, sweetgum, and willow. Unless population levels are very high, GM avoid feeding on conifers, unlike the closely related Asian Gypsy Moth (AGM).

BIOLOGY and DAMAGE:Gypsy moths produce one generation annually and the life cycle consists of four stages: egg, larva (caterpillar, the destructive stage), pupa (cocoon), and adult (moth). GM overwinter as eggs laid in masses covered with a protective layer of hairs from the abdomens of the female moths. Egg hatch and larval emergence usually occur from early spring to mid-May about the time of bud break of preferred hosts, but is affected by temperature and weather.

Newly hatched 1st instar larvae remain near the egg mass for 3-5 days, then climb up the host plant in response to sunlight and begin feeding on leaves in the treetops. Some 1st instar larvae drop down on silken threads and “balloon” to new hosts. Once settled on a suitable host, larvae begin feeding voraciously on the plant leaves and go through a series of instars, or developmental stages, increasing in size with each molt. Males go through five instars and females through six prior to pupation, during a feeding season that lasts 8-12 weeks depending on temperature, food quality, and population levels. Throughout the feeding season, different instar stages may be present at the same time.

During the first three instars, larvae remain in the crowns and top branches of host trees feeding during the day and resting at night. When populations are moderate, late instar larvae will feed in the crown at night then crawl down the trunk at dawn to rest in sheltered spots during the day (e.g., under bark flaps, in crevices, or the undersides of branches). At dusk they return to the top branches to feed. When populations are high, late instar larvae feed continuously day and night until the tree is stripped of all foliage. By June, late instar caterpillars eat entire leaves and may consume up to one square foot of foliage a day. During severe outbreaks, caterpillars crawl away from stripped trees by the thousands in search of new hosts to devour.

GM caterpillars reach maturity between mid-June and early-July then seek a sheltered place to pupate. Caterpillars crawling about searching for a place to pupate become a

1st instar GM larvae hatching from egg mass. USDA Forest Service, Bugwood.org

1st instar GM larvae ballooning on silken threads. A. Steven Munson, USDA Forest Service, Bugwood.org

Pre-mature GM larva and typical mid-instar feeding damage to leaf. Susan Ellis, Bugwood.org

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huge nuisance as they congregate in great numbers on lawns, sidewalks, vehicles, sides of buildings, etc. If populations are sparse, caterpillars will pupate under bark flaps, in crevices, underneath branches or in leaf litter on the ground. If populations are dense, caterpillars may pupate anywhere, in sheltered or unsheltered locations, even exposed on tree trunks or the foliage of non-host plants. Pupation lasts 10 to 14 days, and adult moths emerge from late-June through late-July. Adult moths are typically active through mid-August, and live only about a week, dying shortly after mating and laying eggs.

Adult moths do not feed; their only function is to mate. Males emerge first and, unlike most moths, which are nocturnal, GM fly during daylight hours in rapid zigzag patterns searching for females. Females, despite their fully developed wings, cannot fly and do not stray far from their pupal cases. Females emit a chemical scent, or sex pheromone, that attracts the males. After mating, each female lays a single, buff colored egg mass containing 100 to 1,000 eggs. Egg masses may be found under loose bark or in tree cavities, on tree trunks or branches, on outdoor furniture, vehicles, exterior walls of homes, and piles of wood and lumber.

When GM populations peak, larval feeding may be so intense that trees are completely defoliated. Deciduous hardwood trees with less than 50% defoliation of the crown typically put out new leaves that season and survive the attack, depending on other factors such as drought. Healthy trees can usually withstand one or two consecutive years of defoliations greater than 50%, but with each refoliation, more nutritional reserves are depleted, weakening the trees. Weakened trees become more vulnerable to other stressors such as insects, disease and drought. Deciduous trees may die after several consecutive years of complete defoliation, but evergreens (conifers) are not able to refoliate, and extensive defoliation can kill them in one season.

Major infestations of GM are cyclical. Periods of peak outbreak may last several years and are usually ended by disease or other natural factors. Following this, populations build back up again over the next four to six years. During the early building phase, little visible defoliation occurs. During severe outbreaks though, thousands of acres of trees may be visibly defoliated, and at epidemic levels up to 90% tree mortality can occur. Gypsy moth damage affects timber quality and quantity, the quality of surface water sources, the ecosystem and wildlife habitats, and outdoor recreation and quality of life for humans.

IDENTIFICATION:• Female moths are creamy white with wavy black markings on the wings, and thin antennae.

• Females are large, with wingspans up to 2½” (6.4 cm), and stout bodies that can exceed 1” in length (2.5 cm).

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Adult GM: female (top) and male (bottom). USDA APHIS PPQ, Bugwood.org

Mature GM larva. E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, Bugwood.org

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Defoliation damage from heavy infestation of GM larvae. Haruta Ovidiu, University of Oradea, Bugwood.org


• The female’s enlarged abdomen is covered with light yellow hairs and no markings.

• Despite well-developed wings, females cannot fly and crawl only short distances.

• Male moths are mottled brown (tan to dark brown) with wavy black wing markings, and oblong, feathery antennae.

• Males are smaller, with slimmer bodies, and wingspans of about 1” (2.5 cm).

• Males have well developed wings and are strong fliers, active primarily during the day.

• Egg masses resemble domed, oval shaped pieces of chamois leather stuck to tree trunks and other surfaces.

• Egg masses are 1-2” long (2.5-5 cm), ¾-1” wide (2-2.5 cm), and contain 100 to 1000 eggs.

• Egg masses are covered with buff colored hairs from the females’ abdomens, but may fade to gray with time.

• Older egg masses have pin-sized holes on the surface left by emerging larvae.

• 1st instar larvae hatch out about 1/8-1/5” long (3-5 mm); are initially buff colored but soon turn black; head capsule is black; body is hairy.

• 2nd instar larvae are 1/5-2/5” long (5-11 mm); mostly black with yellow/brown markings down the middle of the back; head capsule is black; body is hairy.

• 3rd instar larvae are 2/5-3/5” long (10-16 mm); black with a central yellow/brown stripe and 11 pairs of blue spots down the back; head capsule is black; body is hairy.

• Instars 4, 5 and 6 are similar to each other: 3/5-2½” long (15-64 mm); dark gray, very hairy bodies, with a central yellow stripe and a distinctive double row of 5 pairs of raised blue spots followed by 6 pairs of raised red spots down the back (some variation in spot colors can occur); head capsule yellow with black markings.

• Pupae are encased in dark red-brown, smooth, teardrop-shaped skins with sparse tufts of buff-colored hairs.

• Pupae vary in length from 0.6” (1.5 cm) for male pupae to 1.2” (3 cm) for female pupae.

• Pupae are motionless and freely suspended or webbed in place with a few strands of silk.

WHAT TO LOOK FOR:• Egg masses resembling small pieces of buff colored chamois stuck on tree trunks, undersides of branches, under loose bark, in tree cavities, outdoor furniture, boats, trailers vehicles, camping equipment, piles of wood and lumber, etc., found fall through early spring.

• Feeding damage in early May of 1st instar larvae may resemble small shotgun holes in leaves.

• As larvae grow, the holes become larger and feeding occurs along the leaf margin.

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Female GM laying egg mass. Steven Katovich, USDA Forest Service, Bugwood.org

GM larval instars with dime for size comparison. USDA Forest Service - Rocky Mountain Region Archive, Bugwood.org.

The antennae of the adult female GM (left) differs significantly from that of the male GM (right). Female GM: USDA APHIS

PPQ, Bugwood.org. Male GM: Louis-Michel Nageleisen, Département de la Santé des Forêts, Bugwood.org


• 2nd and 3rd instar larvae feed from the outer edge of the leaf toward the center.

• 5th instar larvae consume the entire leaf, leaving only the midvein.

• Defoliated trees; twig and branch die-back in upper crown; sprouting of old buds on the trunk and larger branches.

• In wooded suburban areas during severe outbreaks GM larvae crawl up and down walls, across roads, over outdoor furniture, in pools, on and even inside homes.

• Caterpillar silk strands, frass (droppings), leaf litter and dead moths may be abundant.

• Plain brown male moths flying during daylight hours.

MONITORING: The female gypsy moth produces a sex-attractant odor, or pheromone, which attracts males from great distances. Gypsy moth detection programs in uninfested areas rely on using traps baited with synthetic pheromones to capture male moths and determine the presence and population size of this pest. In already infested areas, visual egg mass counts are conducted to estimate GM population levels for the upcoming season. The USDA Forest Service in collaboration with NASA is using the MODIS satellite system to map GM defoliation episodes to model estimates of future defoliation and to assist in planning surveys.

MANAGEMENT:Management of GM occurs at federal, state and local levels, and programs vary depending on whether GM are established (quarantined areas), are not established (non-quarantined areas), or are located at the leading edge of the GM infestation (transition zone). USDA agencies, state and local governments cooperate in using various Integrated Pest Management (IPM) strategies to control GM outbreaks depending on the location of the infestation. In the East and Northeast where GM are long established, suppression and slow-the-spread (STS) programs are used. Suppression reduces GM populations within quarantined areas, and STS mitigates the impact of GM in the transition zone along the edge of a suppression zone. In non-quarantined areas of the U.S. where GM are not established, newly detected infestations are quickly eradicated, and to date this has kept the rest of the nation free of GM.

In severe GM outbreaks, management tactics available to homeowners are not effective, and area-wide management programs are indicated. The impact of pesticides sprays must be balanced against environmental, economic and sociological losses from wide-spread defoliation and infestation of GM. Eventually, under the right weather conditions, naturally occurring diseases of GM can build up and cause significant mortality. As GM numbers slowly build back up following a population crash, parasites and predators are able to help keep GM numbers under control for a few years. Ultimately, IPM control measures will be needed again.

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GM pupae: female (top) and male (bottom). Milan Zubrik, Forest Research Institute - Slovakia, Bugwood.org

Early-instar feeding damage and pre-mature GM larva. USDA APHIS PPQ, Bugwood.org

GM frass and leaf litter in severe infestation. John H. Ghent, USDA Forest Service, Bugwood.org

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RegulatoryThe GM is a regulated pest, and the USDA (Forest Service, APHIS and PPQ) partners with state and local governments and Canada to conduct a regulatory program aimed at limiting the spread of GM beyond quarantined areas. Federal regulations prohibit the movement of certain articles from quarantined parts of the U.S. to any unregulated part of the nation. As of 2008, these areas are under full quarantine: CT, DE, DC, MD, MA, MI, NH, NJ, NY, PA, RI and VT. Portions of these states are under quarantine: IN, IL, ME, NC, OH, VA, WV and WI. Articles requiring inspection and certification prior to movement include: nursery stock and Christmas trees; logs, pulpwood, bark and bark products; mobile homes and associated equipment; and outdoor household articles, such as outdoor furniture, barbecue grills, firewood, doghouses, recreational vehicles, trailers, garbage containers, bicycles, tires, tents, awnings, garden tools, etc.

Government efforts to regulate GM have succeeded in reducing or maintaining GM populations in generally infested areas. An STS program implemented in the eastern U.S. in 1999 has successfully slowed the movement of GM into transitional zones contiguous to quarantined areas. Survey and eradication efforts have been very successful in the western U.S. where small infestations are detected nearly annually. Building on lessons learned managing GM in the East, each western state has a cooperative program in place for the early detection of GM using pheromone-baited traps, followed by rapid response and eradication. Eradication of newly detected GM infestations better protects the environment and is more cost-effective than suppression and STS, while also avoiding the economic losses associated with quarantines.

Cultural Control• Horticultural and silviculture practices that improve tree health may help reduce the impact of GM infestation.

• Avoid actions that stress or injure trees.

• Diversify tree and plant species in the landscape to include those not favored by the GM: o Do not plant an area with more than 20% oak trees, and interplant these with trees not favored by GM. o Trees normally not eaten by GM include: American holly, ash, black locust, black walnut, butternut, catalpa, dogwood, hickory, black or honey locust, mountain ash, mulberry, sycamore, tulip or yellow poplar; shrubs such as mountain laurel, rhododendron, and arborvitae; and many conifers such as balsam fir, eastern red cedar, and red spruce.

Mechanical/Physical ControlResearch has shown that during severe GM outbreaks, the various mechanical/physical control options frequently recommended to homeowners cannot protect trees from defoliation, even when used in combination. However, during the years GM populations are building, these measures will help reduce the number of GM on individual properties. Look for egg masses late summer through early spring on trees, fencing, woodpiles, buildings, lawn furniture and vehicles. Wear gloves to avoid reaction to the hairs covering the egg masses. Scrape egg masses into bags for disposal, or into soapy water to destroy. Make property less attractive to GM by removing objects outside the home that could provide shelter for larvae or pupae, such as old tires, empty containers, outdoor tools or furniture, and dead trees or branches.

Two banding methods can be used to capture GM on residential properties: sticky bands and hiding bands. Homeowners can apply either commercial or homemade sticky barrier bands chest-high on tree trunks to entangle larvae moving up or down the tree. Commercial barrier bands of double-sided sticky tapes are available, or homeowners can apply a 2” wide strip of duct tape that completely encircles the tree, and paint the outer surface with sticky material such as Tanglefoot, petroleum jelly, or grease. Avoid putting sticky materials directly onto the bark of the tree, as petroleum-based sticky products used this way can cause swelling and cankering, especially on thin barked trees such as beech or birch. Barrier bands should be put in place by April and inspected weekly to repair tears or to reapply sticky materials.


Application of a burlap band to monitor GM. Pennsylvania Dept. of Conservation and Natural Resources, Bugwood.org

The second banding method offers shelter for GM to hide beneath. Burlap strips 18” wide and long enough to encircle the tree are tied to the trunk at the midline of the strip, so that the top half folds over the tie string, creating two 9” flaps. Later instar larvae will congregate under both flaps during the day seeking shade and shelter, and the bands will also attract female moths ready to lay eggs and larvae ready to pupate. Burlap bands must be in place by early June, and should be checked daily or at least every other day. Destroy any caterpillars, moths, egg masses or pupae found there. Burlap bands can be used together with barrier bands; place the burlap bands at least 18” higher than the sticky band.

Biological ControlThere are a number of microbial and biological pesticides that have proven effective in controlling GM. These include naturally occurring bacteria, viruses and fungi, and man-made synthetics of naturally occurring organisms. Microbial and biological pesticides contain living disease organisms that must be eaten by GM caterpillars, and are most effective if applied before the larvae reach the 3rd instar. As larvae mature, they become more resistant to microbial pesticides and harder to kill. In general, these pesticides are applied as aerial sprays over large areas by state Departments of Agriculture. Homeowners may have relatively small trees treated using hydraulic applications. Biological control options also include parasites and predators.

Bacillus thuringiensis kurstaki (Btk):The most commonly used pesticide in GM suppression and eradication efforts is the soil inhabiting bacterium Bacillus thuringiensis kurstaki (Btk). Btk affects only caterpillars and is harmless to other insects and animals. Once larvae eat leaves sprayed with Btk, they stop moving and feeding, and eventually die. Aerial applications of Btk are a safe and effective way to control GM, but can harm native butterflies and moths in the larval (caterpillar) stage. Btk is only viable for about one week after spraying, so only native Lepidoptera feeding as larvae during mid-May are at risk of injury. The significant negative environmental impacts of GM defoliation must be weighed against potential adverse effects on native Lepidoptera, which may not be able to compete successfully against GM for available resources during an outbreak anyway. Successful control with Btk is dependent on timing of applications and thorough coverage of host foliage, as Btk must be ingested. Two applications are typically required, the first when most of the larvae are 2nd instars, or less than 3/8” (1 cm), and the second before the leaf canopy is fully expanded, in early to mid-May. There are a number of products containing Btk available for homeowner use (Bonide Thuricide, Bonide Dipel WP, Safer Brand Caterpillar Killer, and Natural Guard BT).

Nucleopolyhedrosis virus (NPV):NPV is a naturally occurring nucleopolyhedrosis virus that affects only GM and builds rapidly in dense populations, halting severe GM outbreaks within two or three years of infection. Infected caterpillars appear to wilt suddenly, and hang limply in an inverted “V” position from the surface they had occupied. NPV is a devastating disease that kills both larvae and pupae of the GM. A microbial pesticide form of NPV has been developed and registered as Gypchek®. However, due to complications with the manufacturing and formulation of this product it is seldom used.

Entomophaga maimaiga fungus:A pathogenic fungus with an unusual history has recently caused significant GM mortality in North America. The fungus, Entomophaga maimaiga, was introduced into the U.S. in 1910/1911 from Japan to control GM, and then went undetected for decades. In 1989 and 1990, population crashes of GM in the Northeast were discovered to be caused by this fungus, instead of NPV as had been expected. Why the fungus was not seen in the intervening eight decades remains unknown. Following infection with the fungus, caterpillars die and are found hanging in a head down, vertical position with prolegs extended to the side. The dead bodies have a dried appearance. E. maimaiga spreads rapidly when weather conditions are favorable, but it is highly dependent on adequate rainfall to be effective. Prolonged drought eliminates this weapon from the naturally occurring arsenal available for combating GM.

Spinosad:Spinosad is another biological pesticide derived from a naturally occurring microbe. Spinosad kills somewhat larger caterpillars in addition to small ones. A number of products containing spinosad are available to homeowners. (Monterey Garden Insect Spray, Green Light Lawn and Garden Spray, Bull’s-Eye Bio-insecticide, and Ferti-Lome Borer, Bagworm, Leaf Miner, and Tent Caterpillar Spray.)


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Larva killed by NPV; note typical inverted “V”position. Pennsylvania Dept. of Conservation and

Natural Resources, Bugwood.org.

Parasitoids and Predators:Native predators are important in controlling GM when the population density is low. However, when GM populations begin building up, natural predators are unable to prevent an outbreak. Native predators include several species of birds (including chickadees, blue jays, nuthatches, towhees, robins and flocking birds such as starling, grackles, and red-winged blackbirds), about 15 species of small woodland mammals (including mice, shrews, chipmunks, squirrels, and raccoons), many species of spiders, and a number of parasitic and predatory insects such as wasps, flies, ground beetles (ex., Calosoma beetle), and ants. Over 20 alien insect parasitoids and predators of GM have been introduced into the U.S. over the past 100 years, including parasitic wasps in the genus Trichogramma, but none have proven effective at controlling GM.

Chemical ControlChemical pesticides may be contact or stomach poisons, so the timing of application tends to be less critical than that of microbials and biologicals, which often target early instars. However, some chemical pesticides tend to impact non-target organisms and may be more hazardous to human health than biological pesticides. Carbaryl and acephate are still available to professionals and homeowners, and during peak outbreaks provide an effective method to kill GM larvae and protect individual high value trees. Both pesticides, however, are toxic to bees and some GM parasites. Malathion, methoxychlor, phosmet, trichlorfon, and synthetic pyrethroids have also been registered by EPA for control of gypsy moth, but are used infrequently. These products are usually not used in GM suppression programs. Contact your local Cooperative Extension Service office for current pesticide recommendations.

The insect growth regulator diflubenzuron (Dimilin®) is sometimes used as an aerial spray in GM suppression programs. When eaten by immature insects, diflubenzuron disrupts growth by interfering with exoskeleton formation during molts. Diflubenzuron is considered more effective than Btk and has longer residual action, lasting throughout the growing season. However, diflubenzuron also can disrupt the molting process of non-target organisms such as aquatic arthropods and cannot be used over open water.

Mating disruption by the aerial application of flakes of the synthetic gypsy moth sex pheromone, disparlure, can suppress low gypsy moth populations. Males become disoriented when the synthetic pheromone saturates the environment, and fail to find and mate with females. Mating disruption may be used in environmentally sensitive areas, and at the leading edge of transitional zones to delay establishment in new areas. Registered synthetic versions of disparlure are available in products such as Disrupt®II, Luretape Gypsy Moth®, and Luretape Plus®.

LOOK-ALIKE INSECTS and DAMAGE:• Both male and female GM are nearly identical to the Asian Gypsy Moth (AGM), except AGM is slightly larger (AGM: female wingspan ~ 3½” or 8.9 cm; male ~ 1½” or 3.8 cm).

• Adult male GM may be confused with numerous other plain brown moths, but GM are one of very few moths active during the day.

• Adult female GM cannot fly; however, the larger look-alike AGM female is a strong flyer.

• Because AGM females can fly, they are attracted to lights. Because GM females cannot fly, they remain near their pupation site their entire lives.

• Cankerworms feed about the same time as GM on the same host trees, but they are green or dark brown in color, sometimes striped, and have a smooth, hairless appearance.

• Tent caterpillars are dark and hairy and often confused with GM larvae, but they emerge 3-4 weeks earlier than GM, so are usually large (up to 2” or 5 cm) by the time GM hatch. Tent caterpillars can also be distinguished by white stripes or rows of irregular white spots down the middle of their backs, and bright blue stripes along their sides. The eastern tent caterpillar builds tents of white silk in the crotches of tree branches; GM never build such tents.

• Fall webworms are hairy, light yellow or brown in color, and first appear in mid to late June on a variety of trees. They are most abundant in July and August, long after GM caterpillars are gone. Fall webworms build webs at the tips or tree branches; GM never build such tents.


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Where to Get More Information:UMD Extension Exotic Pest Threats Website: http://extension.umd.edu/ipm/pest-threats

USDA APHIS Pests and Diseases website: http://www.aphis.usda.gov/plant_health/plant_pest_info/gypsy_moth/egm-background.shtml

Look-alikes:USDA Forest Service Forest Health Protection, GM versus AGM (power point): http://www.ipmimages.org/spdn/invasive/presentations/8Leonard.pdf

Images: Forest Pests/Bugwood: http://www.forestpests.org/subject.html?SUB=165

Project Participants: Chris Sargent, Research Assistant; Michael Raupp, Entomologist; Sandra Sardanelli, IPM Coordinator; Paula Shrewsbury, Entomologist; David Clement, Pathologist; Mary Kay Malinoski, Entomologist.

Selected References:Campbell, F. 2004. European Gypsy Moth. The Nature Conservancy Global Invasives Species Team:http://www.dontmovefirewood.org/gallery-of-pests/european-gypsy-moth.html

McManus, M., N. Schneeberger, R. Reardon, G. Mason. 1992. Forest Insect & Disease Leaflet 162. U.S.D.A. Forest Service: http://www.na.fs.fed.us/spfo/pubs/fidls/gypsymoth/gypsy.htm

Pederson, L. and S. Munson. 2006. Gypsy Moth Biology and Management. Forest Health Protection and State Forestry Organizations

Raupp, M. J., J. A. Davidson, F.E. Wood. 2008. The Gypsy Moth and the Homeowner, Fact Sheet 242. University of Maryland: http://extension.umd.edu/sites/default/files/_docs/articles/FS242_GypsyMothAndHomeowner.pdf


Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, University of Maryland, College Park, and local governments. Cheng-i Wei, Director of University of Maryland Extension, University of Maryland.

The University of Maryland, College of Agriculture and Natural Resources programs are open to all and will not discriminate against anyone because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, or national origin, marital status, genetic information, or political affiliation, or gender identity and expression. Inquiries regarding compliance with Title VI of the Civil Rights Act of 1964, as amended; Title IX of the Educational Amendments; Section 504 of the Rehabilitation Act of 1973; and the Americans With Disabilities Act of 1990; or related legal requirements should be directed to the Director of Human Resources Management, Office of the Dean, College of Agriculture and Natural Resources, College Park, MD 20742. 9

How to Report a Possible Sighting/Infestation

In Maryland:University of Maryland Extension Exotic Pest Threats Website: http://extension.umd.edu/ipm/pest-threatsMaryland Department of Agriculture: call 410-841-5920 to report suspect pests; visit http://mda.maryland.gov/plants-pests/Pages/invasive_species.aspx for information.

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gypsy moth - university of maryland...the gypsy moth is native to most of temperate europe, asia and...

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