Friday, April 13, 2007

Eastern Tent Caterpillar

I have already begun to see the familiar nests of the Eastern Tent Caterpillar around Haywood County. This insect, although not extremely destructive, causes unsightly nests in the croches of several tree species.

Eastern tent caterpillars are found throughout eastern North America. Wild cherry, crabapple and apple are the usual hosts of the eastern tent caterpillar, but many other kinds of trees are occasionally infested. Eastern tent caterpillars feed in groups and may completely strip the new leaves from trees. The tents are unattractive as well. Trees defoliated for several years by eastern tent caterpillars may decline noticeably. Although the caterpillars are not harmful to man, many people find them to be repulsive as the caterpillars crawl about seeking places to spin their cocoons.

Only one generation of eastern tent caterpillars develops each year. In spring as new leaves develop, the caterpillars leave the eggs and begin to feed and spin silken webbing. After about two days, they begin weaving a tent in a crotch of a branch. As the caterpillars grow, they spin successive layers on the tent. In good weather, the caterpillars leave the nest several times each day to feed. In bad weather, the caterpillars remain in the nest. About 6 weeks after hatching, the caterpillars leave the nest and crawl to spin their cocoons on fences, tree bark, buildings or debris.

Once inside the cocoon, the caterpillar develops into the pupal stage. In early summer, adult moths molt from the pupal stage and emerge from the cocoons to mate and lay eggs. The caterpillars develop inside the eggs, but they do not hatch until the following spring. They spend the summer, fall, winter and very early spring inside the egg mass.

Because eastern tent caterpillars spend the winter inside the egg masses, one effective method of controlling the caterpillars is to remove and destroy the egg masses before the caterpillars hatch. If the caterpillars have already hatched, the tents can be pulled down with a stick and the caterpillars crushed or otherwise destroyed . Never use fire to destroy eastern tent caterpillars as fire is extremely dangerous. Fire may damage the tree and endangers the operator and nearby property. The following pesticides are a few of those suitable for use to control eastern tent caterpillars on ornamental plants. Be sure to follow the directions for safe use found on the label of whichever pesticide is selected. Treat foliage nearest web.

acephate (Orthene) 9.4 EC
carbaryl (Sevin)

For more information, contact your local Extension office.

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