Eastern Tent Caterpillar

Eastern Tent Caterpillar


The eastern tent caterpillar is a common native defoliator in the eastern U.S. Normally, the eastern tent caterpillar is only a nuisance or an aesthetic problem, but populations are cyclical and outbreaks occur on average at ten year intervals. During outbreak years, individual trees can be heavily infested and defoliated. Control is usually not necessary because trees can survive these occasional attacks and caterpillar populations soon decline. 


Eastern tent caterpillars are so named for the silken tents which colonies of larvae construct. Tents usually begin in a branch crotch, and grow in size along with the caterpillars. During heavy infestations, entire trees can be covered with webbing and trees can be completely defoliated. Fully grown larvae have black heads, are lightly covered by brown or yellow hairs, and can be up to 2 1⁄2 inches long. Wavy yellow and blue lines run down the sides of the caterpillar on a black background; a row of blue and black spots run between these stripes. Eastern tent caterpillar larvae are easily confused with the forest tent caterpillars, but differ in that they have a solid white line that runs down their back (forest tent caterpillars have white spots running down their back). Adult moths have a 2 inch wingspan, are reddish-brown or yellow-brown, and have two narrow white stripes running across each forewing. Eggs are brown or black in color, cup-shaped, and laid in masses of several hundred individuals that are covered in a varnish-like protective coating. Egg masses are spindle-shaped, less than 1 inch long, and completely encircle small twigs). 


Control is usually not necessary. Trees usually produce new leaves by early to mid-summer. Insecticides are available to protect valuable fruit trees and ornamentals. Caterpillars can be picked from small trees by hand. Tents can be clipped off or gathered up and destroyed on cool rainy days when larvae are inside. Egg masses can also be located and clipped off of trees during the winter months. 

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