EASTERN TENT CATERPILLARS

The silken nests of eastern tent caterpillars will be starting to appear in the Shelby Township area soon. The eastern tent caterpillar is partial to cherry, apple, and crabapple trees, but they’re not opposed to infesting your peach, plum and pear trees, as well.

Eastern Tent Caterpillar Damage

The eastern tent caterpillar can potentially defoliate a small to mid size tree.

Identification

The silk nest is a dead giveaway that you have eastern tent caterpillars in your tree. As soon as the young caterpillars hatch from the egg mass they will look for the nearest suitable crotch in the tree (branch or main stem) and begin construction of a nest. The eastern tent caterpillar nest is built in layers. With each succeeding layer the nest grows in size. Depending upon the number of individuals in the colony, a mature eastern tent caterpillar nest may range in size from a baseball to a softball. The nest is home base for the colony. They move in and out of the nest several times throughout the course of a day.

Homeowners in Shelby Twp. occasionally confuse the eastern tent caterpillar with the gypsy moth caterpillar. Both grow to be big hairy caterpillars and both occur in the spring. However, in Shelby Twp. the eastern tent caterpillar hatches nearly a month before the gypsy moth. The eastern tent caterpillar also looks different from the gypsy moth. Where the gypsy moth has a series of blue dots followed by red dots on its back, the eastern tent caterpillar has a white stripe down the middle of its back.

The eastern tent caterpillar does not appear in your tree out of the blue. The egg mass was probably there since the previous summer (July). Once the leaves fall, the egg mass is easier to spot. It looks like a dark swelling of a twig or small branch. The eggs are covered with an excreted fluid that hardens and takes on the appearance of a shiny dark varnish. The caterpillars hatch early in the spring because the embryo is completely developed by first frost. An egg mass will contain 150 to 350 eggs.

There are several means available to control eastern tent caterpillar.

Cultural Control

As soon as the leaves fall, check susceptible tree species in your landscape. Pay special attention to any trees that had a nest the previous spring. The egg masses can be removed by hand. This control method is particularly effective on your smaller trees, which can be completely examined. You can either scrape off the egg masses or clip off the branch if it’s not going to affect the appearance of the tree.

If you see tents being formed in the spring you can remove the actual nest. Wind up the nest and caterpillars on a stick and dispose of them in your garbage.

Biological Control

There are several natural enemies that attack and thrive on eastern tent caterpillars in Shelby Township. In particular, the northern oriole thinks it has died and gone to heaven when they find a tree with eastern tent caterpillars. Also attacking eastern tent caterpillars is a parasitic fly which looks like an overgrown house fly. The fly maggot burrows into the caterpillar, but doesn’t finish it off until it pupates. There are also other birds, beetles and wasps that dine on this caterpillar.

Chemical Control

Tree spraying options include both organic and traditional insecticides. If the caterpillars are less than 1/2 inch in length a Bacillus thuringiensis (B.t) spray can be applied. For larger caterpillars, there are several insecticides labeled for control of eastern tent caterpillars.