Eastern Tent Caterpillar
Author: Eric R. Day; Manager, Insect Identification Laboratory; Virginia Tech
Publication Number 444-274, June 2002
Lepidoptera: Lasiocampidae, Malacosoma americanum (F.)
Plants Attacked
Black cherry, chokecherry and apple are favored; also feeds on hawthorn, pear, plum, and flowering fruits.
Description of Damage
Defoliator. The larvae initiate small webs in branch crotches as soon as eggs hatch. As the larvae feed on the foliage, they continually increase the size of the web until it is a large nest or tent, a foot or more in length. Most larvae crawl back to the tent at night, but forage out to feed during the day, defoliating increasingly larger portions of the branches and tree.
Identification
The larval or caterpillar stage is brown and is quite hairy. It has a white stripe running down the back that is bordered by yellow brown. In addition the caterpillar has a row of blue spots down each side. The adult moth is a dark tan color with two pale stripes on each of the front wings. Although similar they are not the same insect as a gypsy moth.
Life History
Winter is spent in the egg stage as one of many in a dark brown varnished collar or belt encircling the twigs. The young larvae hatch at or before bud growth in March or April and gather in a fork of the limbs to spin their large web nests. The larvae leave during the day to feed, but return to the nest at night, or during rainy weather. They are full grown (2 to 2 1/2 inches) in 4 to 6 weeks and often crawl to nearby buildings or protected places to spin their dirty white cocoon. The moths emerge in about three weeks and each female lays an egg collar (containing 150 to 350 eggs) around a twig. There is one generation per year. They overwinter in egg masses on small twigs.
Control
During the fall and winter months, cut off and destroy all egg masses that are found on the twigs. If you are spraying, early control is important. However, it is difficult because larvae begin feeding on leaves unfolding from the bud before there is adequate leaf surface to be sprayed. Insecticides with residual effectiveness are desirable. Most will kill larvae hit by the spray; however, larvae in webs are protected from sprays. Treat foliage and twigs during the day as the caterpillars hide in the webs at night. If treating fruit bearing trees, use an insecticide labeled for use on fruit trees.
Remarks
Larvae most frequently cause concern when migrating to protected places to hibernate. They crawl on other types of plants, roadways, walks, buildings, etc., thus suggesting infestations elsewhere than on the host. No further feeding occurs when larvae are mature and migrate. Insecticides are generally ineffective against mature larvae.
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