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Caterpillar Comparison Chart

Comparison Chart
Forest Tent Eastern Tent Spongy Moth (formerly gypsy moth)
Eggs Dark compact cylindrical mass with square ends, encircling the branch. New masses are shiny without holes. Old masses are dull and show exit holes. Deposited around small twigs in July. Masses may contain up to 350 eggs, average 150 in NY. Dark compact cylindrical mass with tapered ends encircling the branch. New masses are shiny without holes. Old masses are dull and show exit holes. Deposited around small twigs in July. Masses contain up to 350 eggs. Tan-colored or lighter fuzzy patches (masses) on tree trunks, branches, firewood, or in a sheltered spot, even on lawn furniture. Usually 600-700 eggs/mass.
Egg Mass
forest tent egg mass
eastern tent caterpillar egg mass
(Ansel Oommen,
spongy moth larvae on egg mass
Larvae (caterpillar) appearance Dark with light blue lines down sides and line of white "footprints" down back. Light blue heads. Fully grown is about 2 inches long. Dark with white line down back with light blue and black spots on sides. Black head. Fully grown is about 2 - 2 ½ inches long. Five pairs of raised blue spots followed by six pairs of raised red spots along back. Fully grown is about 2 inches long.
forest tent caterpillar
(Whitney Cranshaw, Colorado State University,
eastern tent caterpillar
(Lacy L. Hyche, Auburn University,
spongy moth caterpillar
Minnesota Department of Natural Resources Archives,
Larvae behavior Hatch at bud break in spring. Tend to migrate to treetops. Feed on opening buds and new foliage one branch at a time. Young larvae are gregarious, often group together, follow each other in a line, and form silken mats on trunk, branch or leaves where they gather, rest and molt. Older larvae are nomadic foragers even prior to complete defoliation. Hatch at bud break in spring. Congregate in obvious silken tents in branch forks. Feed on opening buds and new foliage in colonies. Use tent to rest and as protection from extreme temperatures, rain, birds and other predators. Larvae leave the tent to feed. Fully grown larvae leave the host tree to find a protected place to pupate. Hatch when oak buds are opening. Younger larvae chew small holes in the leaves. Older larvae feed from the outer edge of the leaf toward the center. Will feed until tree is stripped, then go in search of food. When feeding will leave behind noticeable frass (droppings). When populations are sparse, larvae feed at night, crawling down the trunk to hide in a protected spot during the day. When populations are dense, feeding occurs day and night. When tree is stripped, larvae go in search of new food sources.
Pupa Solitary cocoons, pale yellow silk in folded leaves or protected areas Solitary cocoons, white silk with yellow powder Hard brown case, pointed at one end in sheltered location
Adult moths Light brown with two narrow dark bands/stripes on the forewings. Lay eggs on hosts. Strongly attracted to light. Sexes look similar. Reddish brown with two white stripes on forewings. Sexes look similar. Females do not fly. Females are white with brown markings. Males are brownish.
Adult forest tent caterpillar moth eastern tent caterpillar moth spongy moth caterpillar moth
Most common host trees Sugar maple, aspen, cherry, apple, oaks, birch, ash, alder, elm, basswood and willow. Does not feed on red maple, sycamore or conifers Mostly cherry, apple, and crabapples, also other fruit trees ash, birch, maple, oak, poplar, and occasionally pecan, hawthorne, beech and willow Oaks preferred. Also apple, sweetgum, speckled alder, basswood, gray and white birch, poplar, willow and others. Avoid ash, yellowpoplar, sycamore, black walnut, catalpa, locust, American holly, and shrubs such as mountain laurel, rhododendron and arborvitae. Older larvae will also feed on conifers such as hemlock, pines, spruces and southern white cedar. When populations are dense, larvae will feed on almost any tree and shrub.
Other Native Native Introduced in 1869. Currently found in 19 states.