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Gypsy Moth
Order: Lepidoptera
Family: Lymantriidae

Scientific name: Lymantria dispar (L.)
Common name: Gypsy moth (GM)

Adult male: wings are dark brown with black bands across the forewings. The wingspan is about 1.5 inches (38 mm).
Adult female: wings are creamy white with dark bands across the forewings. The wingspan is about 2 inches (51 mm).
Larvae: mature larvae are brownish-black and covered with light hairs. Along their backs they have five pairs of blue bumps followed by six pairs of red bumps. A yellow line runs along the back from the head to the last body segment.
Pupae: chocolate brown to dark reddish-brown and teardrop-shaped with the head rounded and the rear tapered.
Eggs: round white eggs are laid in a 1/2-2 inch (13-51 mm) mass which are covered by buff-colored hairs from the female’s abdomen.
gypsy moth male
gypsy moth adult female with egg mass
gypsy moth larva
Damage: The larval (caterpillar) stage is the stage that causes the damage. The larvae consume tremendous amounts of leaf material. They can consume as much as one square foot of leaves per day.
Impacts: The gypsy moth is one of the most destructive defoliators of hard and softwood trees. The larvae can cause substantial defoliation that may lead to tree mortality. Defoliated forests are susceptible to disease, fire, and erosion, and may provide a poor habitat for other forms of animal and plant life. Not only do they strip trees and shrubs of foliage, they can be a nuisance to people when they crawl on sidewalks, patios, houses, and other structures, and when they create a continuous rain of messy droppings under infested trees. In some cases, people develop an allergy to the hairs of the gypsy moth larvae.
Host plants: The preferred host plant is oak but, larvae feed on close to 500 deciduous trees and shrubs.
Distribution: Gypsy moth is distributed in the northeastern states including Connecticut, Delaware, the District of Columbia, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont. Parts of Maine, Michigan, North Carolina, Ohio, Virginia, West Virginia, and Wisconsin are also infested with gypsy moth. Isolated infestations have also appeared in states outside the northeastern region such as Oregon, California, and Washington.
distribution maps
Biology and Life Cycle: Gypsy moth has one generation per year and overwinter as eggs. After mating, each female produces an oval-shaped egg mass which can contain up to 1000 eggs. The larvae hatch in mid-April to mid-June the following year. Mature caterpillars enter the pupal stage in July, emerging from dark brown pupal cases in 10 to 14 days as adults.
How you can help: Report suspected gypsy moth life stages to Oregon Department of Agriculture.
1. Encourage anyone you know who has moved here recently from the northeastern U.S. to contact the Oregon Department of Agriculture for a free inspection of outdoor household articles and recreational vehicles.
2. Cooperate with Oregon Department of Agriculture seasonal survey staff when they request permission to place traps on your property during the summer.
3. Observe quarantine regulations by not moving wood products, firewood, plant material, outdoor household articles, or recreational vehicles out of gypsy moth infested areas without certification.
4. Be expecially alert for and report to ODA any suspected egg masses and pupae which can travel to the U.S. on cargo, containers, and conveyances from Europe, Russia, China, and other infested areas.
What ODA is doing: Each year ODA places approximately 18,000 gypsy moth traps across the state. Placing traps allows ODA to detect any infestations when they are small and when they are more easily eliminated.
ODA's Plant Division Annual Report
USDA Forest Service: Gypsy Moth in North America
ODA's gypsy moth flyer (pdf, 354 KB)