Information on Tent Caterpillars

Eastern Tent Caterpillar is an insect pest found on cherry and apple trees during the early spring in Maryland.  This spring the infestations have been unusually heavy.  It is startling to look out in your yard and find a tree that several days earlier had that beautiful spring green completely stripped of foliage with these ugly nests in the forks of the branches.  At this stage, there is no point in trying to control this pest.  Both cherry and apple trees are very resilient and within 2-3 weeks the trees usually revive and form new leaves. 

The moth species overwinter as eggs on branches and twigs.  They hatched about 3-4 weeks ago and begin to feed on foliage as small caterpillar larvae.  In great numbers they can quickly defoliate a tree as the larvae develop into mature caterpillars.  The caterpillars weave nests in the forks of branches and usually take refuge in the nests during the day and emerge to feed a night or early in the morning.  The mature caterpillars will drop out of the nests and trees and pupate.  From the pupae moths emerge; mate and the females lay new eggs on tree branches to renew the cycle for the next spring. 

This pest can be controlled mechanically by destroying the egg masses, before the eggs hatch.  If the nests are within reach, they can be gathered by hand or by pruning out the nests during the day.  Squashing them under foot, or dumping them in a can or bucket of soapy water kills the collected eggs or caterpillars.  The leaves can also be sprayed, when the caterpillars are small, with a bacterial spore preparation called Bacillus thuringiensis (Bt).  This is a biological control agent that is safe to the surrounding environment.

http://ohioline.osu.edu/hyg-fact/2000/2022.html

http://www.ca.uky.edu/entomology/entfacts/ef423.asp

http://www.dec.ny.gov/animals/7111.html