Tent Caterpillars

Tent Caterpillars
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In some years, tent caterpillars seem to be everywhere; in others, they drop out of sight. Long-haired, wrinkly, and up to 3 inches long, these pests build gauzy nests in the forks of tree branches. Eastern types are black with a white stripe along the back and blue dots on the sides; western species bear various markings, but all have white dashes. During the day tent caterpillars dine outside their nest- unlike fall web-worms which expand their webs as they feed.

Target: Many trees and shrubs.

Damage: Leaves are chewed; branch forks are covered with webs. Plants may be defoliated.

Life cycle: Gray moths lay eggs masses which often encircle branches and twigs. Caterpillars hatch in early spring and begin making nests. They feed until early summer, then drop to the ground or lower themselves on silken threads, crawl to a protected spot, and pupate. There are up to four generations a year.

Notes: When handpicking, wear gloves to avoid skin irritation. If you see caterpillars with shiny white “seeds” on their heads, leave them alone—the “seeds” are the eggs of parasitic tachinid flies. Spraying with BT won’t harm the flies, which can continue to live off the caterpillars’ dead bodies. Before applying a pesticide, break up the tents with jets of water.