Lymantria dispar Linnaeus, 1758 (Spongy Moth )


John H. Ghent,
USDA Forest Service




Class: Insecta

Order: Lepidoptera

Family: Lymantriidae

Synonym(s): Porthetria dispar

Adult Description: Previously referred to as the Gypsy Moth the common name has changed to Spongy Moth when regarding this invasive species. The adult moths vary in appearance. Adult males are tan to brown in color with irregular black wing markings, feather-like antennae, and a wingspan of 37 to 50 mm. Female adult moths are usually larger, with a wingspan of up to 62 mm. They are whitish in color with faint darker, wavy bands across the wings. The female European gypsy moth is flightless, however the female spongy moth is a strong flier. Asian spongy moths are significantly larger than the European gypsy moths.

Larva Description: Spongy moth caterpillars are hairy, about 2-3 mm long when newly hatched, and grow to about 60 mm long. They have two rows of large spots along the back, usually arranged in five pairs of blue and six pairs of red from head to rear.

Host Plant: 500 species of trees and shrubs

History: Formally known as the gypsy moth. The moth was brought to the United States in 1869 in a failed attempt to start a silkworm industry. Escaping soon after, the spongy moth has become, over the past century, a major pest in the northeastern United States and southeastern Canada.

Biology: ASM infestations spread in several ways. Adult female moths may fly to previously uninfested areas to lay eggs, thus spreading the infestation. Or, newly hatched ASM caterpillars may climb to tree crowns, where the wind picks up their silken thread and carries them to other areas. In addition, people can inadvertently transport egg masses. ASM egg masses are tolerant of extremes in temperature and moisture and travel well on logs, lawn furniture, nursery stock, pallets, shipping containers, and on the hulls and rigging of ships.

Ecological Threat: If established in the United States, each ASM female could lay egg masses that in turn could yield hundreds of voracious caterpillars with appetites for more than 500 species of trees and shrubs. ASM defoliation would severely weaken trees and shrubs, killing them or making them susceptible to diseases and other pests. Caterpillar silk strands, droppings, destroyed leaves, and dead moths would be a nuisance in homes, yards, and parks.

US Habitat:


Native Origin: Asia

US States: Most infestations have been eradicated, but it has been found in Portland, OR as recently as 2000.

Texas: Not currently found in Texas.

If you believe you have found a spongy moth, please report this species.


Management: The most common eradication method used against Asian Spongy Moth is the naturally occurring Bacillus thuringiensis (Bt) bacteria. Bt produces a caterpillar-specific toxin. When sprayed on tree leaves, Bt will disrupt the digestive system of caterpillars that ingest the leaves, suppressing their appetites. The caterpillars' movement then slows, and death results, generally in 7 to 10 days.

Text References

USDA APHIS PPQ. Factsheets: Asian Gypsy Moth. Accessed 05 January 2012:

Data Source


Last Updated: 02-02-2022 by HTG