Forest Resource Protection Forest Health, Insect & Disease Forest Fire Control Staff

How To Identify Which Caterpillar is Eating Leaves

Here are three common caterpillars in forests this year and how to identify which one is causing defoliation of your trees.

Forest Tent Caterpillar

Caterpillars feed on sugar maple, oak, ash, quaking aspen and other leaves.

The caterpillar is hairy, and has a black and blue body with white, keyhole-shaped markings down the center back. It grows to be 2 inches long, stops feeding and forms a cocoon in early July.

Notes: This “tent caterpillar” does not make a web-like tent in the crotches of trees (see Eastern Tent Caterpillar). It is currently in very high populations in southern Vermont and scattered locations in central and northern Vermont.

http://www.na.fs.fed.us/spfo/pubs/fidls/ftc/tentcat.htm

Eastern Tent Caterpillar

Caterpillars feed on cherry and apple leaves.

The caterpillar is hairy, with a black and blue body, and a solid white stripe down the center back. It grows to be 2 inches long, stops feeding, and forms a cocoon in late June.

Notes: This is the “tent caterpillar” that makes a web-like tent in the crotch of trees. Its close relative, the forest tent caterpillar, does not make tents. This insect only feeds on cherry and apple, so, while it can totally strip a tree of leaves, it does not cause large areas of forest defoliation in Vermont.

http://www.na.fs.fed.us/spfo/pubs/pest_al/etc/etc.htm

Gypsy Moth

Caterpillars feed on oak and other hardwood leaves (sometimes sugar maple).

The caterpillar is hairy, black, and has red and blue spots down the center back. It grows to be 2 inches long, stops feeding and forms a cocoon in early July.

Notes: This caterpillar is contributing to defoliation of oak and sugar maples in southern Vermont, in combination with forest tent caterpillars.

http://www.na.fs.fed.us/spfo/pubs/pest_al/gm/gm.htm

Sandy Wilmot

VT Department of Forests, Parks & Recreation

June 2006