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EASTERN TENT CATERPILLAR

James R. Baker, Extension Entomologist Emeritus

CAUTION: This information was developed for North Carolina and may not apply to other areas.

Malacosoma americanum (Fabricius), Lasiocampidae, LEPIDOPTERA

General Information

mass of larvae on twigMoths of the eastern tent caterpillar are brown to reddish-brown with two pale diagonal lines on the forewing. Eggs are laid in masses around twigs and covered with a foamy secretion that dries into a firm, brown covering. Eastern tent caterpillars are somewhat hairy and black with gold, white and blue markings. There is a white stripe down the back. The caterpillars grow up to almost 2 inches long. The cocoon is about 1 inch long and is spun of white or yellowish-white silk.

BIOLOGY

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.

close up of larvaOnly 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.

egg caseOnce 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.

Control

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.  Consult the NC Agr. Chemicals Manual for other chemicals.

Pesticide (Trade Name) 
Formulation
Remarks
acephate (Orthene)
(Orthene TTO)
*9.4 EC
75SP
3 TBS
1 tsp.
*carbaryl (Sevin)
 follow label directions
B.t. (Dipel)   spray foliage near web while larvae small
bifenthrin (Talstar) 7.9F  follow label directions

* formulations suitable for home use.

Other Resources

For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service personnel.

Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance contact an agent of the North Carolina Cooperative Extension Service in your county.
© 2001 NC Cooperative Extension Service
Prepared by: James R. Baker, Extension Entomologist
ENT/ort-62 January 1995 (Revised) 2000

Web page last reviewed January, 2011 by the webperson.