Is it a gypsy moth?

There are a number of bristly, or tufted, caterpillars that are often mistaken for the gypsy moth. The following pictures and descriptions will help you distinguish among them.

Gypsy moth

Distinctive markings: Five pairs of blue dots followed by six pairs of red dots down the length of back.

Behavior: The gypsy moth feeds on oaks, crabapple, linden, willow, birch, aspen, and more than 250 other species of trees. The caterpillars hatch in May and feed through early July. During an outbreak they can strip trees, seemingly overnight. They build no silk tents.

Eastern tent caterpillar

Distinctive markings: Prominent white or yellow stripe running down the center of back, small blue spots on side.

Behavior: This caterpillar constructs tents where branches fork in cherry, wild cherries, crabapple, and apple trees. These caterpillars feed in May and early June on the trees their tents are built in. The tents may linger into the summer before falling apart. Eastern tent caterpillars rarely cause significant damage, though people have done permanent damage to their trees by excessive pruning in cutting out the tents or the use of fire to kill the caterpillars. Instead, tree owners should wait until dusk, then wearing rubber gloves, strip the tent and the caterpillars out of the tree using their hands. The tent and caterpillars can then be plunged into soapy water, buried, or burned away from the tree.

Credit: Gerald Lenhard, Louisiana State University. Image 0795040. ForestryImages.org, November 24, 2001.

Credit: Tim Tigner, Virginia Department of Forestry. Image 0886010. ForestryImages.org. November 24, 2001.

Forest tent caterpillar

Distinctive markings: A velvety, sky blue skin with a black stripe marked with a row of white “footprints.”

Behavior: Despite its name, this caterpillar doesn’t make a tent. Populations increase dramatically about every 10 years in the northern third of Wisconsin. During outbreaks, forest tent caterpillars will strip aspen, oaks, sugar maple, and a few other tree species of leaves in early June. This caterpillar does not feed on evergreens.

Fall webworm

Distinctive markings: Long gray hairs arising from yellow, orange, or black bumps.

Behavior: This insect builds its large nests in mid- to late summer. It only starts to feed after the gypsy moth has emerged as an adult. This caterpillar webs together branches. While these nests can be large, the damage is rarely significant for the tree.

James Hanson, USDA Forest Service. Image 0949061. forestryImages.org. August 21, 2001.

Credit: Tim Tigner, Virginia Department of Forestry. Image 0886009. ForestryImages.org. November 24, 2001.

White-marked tussock moth

Distinctive markings: A bristly “toothbrush” of white hairs on its back and two long tufts of hair projecting from its head and one from its tail.

Behavior: This attractive caterpillar is often a problem in the Milwaukee area on crabapples, elm and other deciduous trees. It typically feeds in June-July.

For pictures of other leaf-eaters, link to the Michigan State University website and view their publication Common Oak Defoliators in Michigan (E-2633)