Spongy Moth (formerly Gypsy Moth) Egg Mass
Scientific Name: Lymantria dispar
Order & Family: Order: Lepidoptera, Family: Erebidae
Size: Egg masses typically measure 1 to 1.5 inches long and 0.75 inches wide.
Natural Habitat
Found on tree trunks (especially oaks, aspen, willow, and birch), outdoor furniture, firewood, sides of buildings, and other vertical surfaces.
Diet & Feeding
As eggs, they do not feed. Upon hatching, the larvae (caterpillars) feed efficiently on the foliage of over 300 species of trees and shrubs.
Behavior Patterns
Females lay eggs in late summer to early fall. The masses are covered in a protective, velvety coating made of the female's body hairs (seen in the image as the yellowish-brown fuzz). They overwinter in this state and hatch in the spring.
Risks & Benefits
Risks: This is a highly invasive and destructive pest in North America. The caterpillars can completely defoliate millions of acres of forest, weakening trees and making them susceptible to other diseases. There are no ecological benefits outside its native range.
Identified on: 3/8/2026