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Home > Bugs > Bugs of Trees and Shrubs > Tent Caterpillars

Tent Caterpillars

Tent caterpillars attack several kinds of broadleaf trees and shrubs and produce unsightly webs, or tents. Trees with substantial defoliation will have reduced growth and vigor. The caterpillars often occur in large numbers which can be a nuisance around homes.

Eastern Tent Caterpillars    
eastern tent caterpillar tent eastern tent caterpillars eastern tent caterpillar up close

Eastern tent caterpillars feed on new leaves, forming small webs within a few days after hatching and enlarging the webs as they grow.

Trees infested with several tents are often totally defoliated. A single occurrence rarely kills a tree, but it does reduce growth and makes the tree more susceptible to other hazards such as drought, freezing, or disease. Eastern tent caterpillars grow to over 1½ inches long. They are brightly colored and have a solid white line down the center of the back and long hairs on their bodies, mostly along the sides.
Forest Tent Caterpillars    
forest tent caterpillar web forest tent caterpillars forest tent caterpillar up close

Forest tent caterpillars build mats of webbing rather than tents. They forage in all directions from these mats but return to the colony when not feeding. Caterpillars feed actively for five to six weeks.

In large numbers forest tent caterpillars can cause serious defoliation to host trees. Usually their numbers are moderate and most of their feeding injury goes unnoticed. The larvae can sometimes be seen clustered in a large group on the trunk of the host.

Forest tent caterpillars are about 2 inches long, mostly blue and black, with a row of white, footprint shaped markings on their backs, and many hairs along the edge of the body.

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[Photos, left to right: Catherine Herms, The Ohio State University,; Joseph O'Brien, USDA Forest Service,; Pennsylvania Department of Conservation and Natural Resources - Forestry Archive,; R.C. Morris, USDA Forest Service,; Whitney Cranshaw, Colorado State University,; Gerald J. Lenhard, Louiana State Univ,]

It is the policy of the State of Maine to minimize reliance on pesticides. The Maine Department of Agriculture and the Maine IPM Council encourage everyone to practice integrated pest management and to use pesticides only as a last resort. The mention of pesticides in the fact sheets linked to these pages does not imply an endorsement of any product. Be sure that any product used is currently registered and follow all label directions.