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Eastern Tent Caterpillars

EASTERN TENT CATERPILLARS
By George Piasecki 1995 Newsletter

Every year about mid-April, we receive many phone calls from concerned home-owners telling us that their trees are infested with gypsy moths or bagworms.

“I can see the gypsy moths eating my cherry tree” or “Yes, I can see the silky white bag” are typical answers to our diagnostic questions. It is too early for any major gypsy moth damage and bagworms live in 2″ elongated “footballs” that appear in July. What they are seeing are the larva and webs of the EASTERN TENT CATERPILLAR.

When the young larva hatch in early April, they start to form their tents in the forks of branches. As the caterpillars feed on the tender foliage and grow, so does the size of the tent, making both very visible to homeowners. Fully developed caterpillars are generally black and about 2 inches long. There is a white stripe down the back and a series of blue spots between elongated yellow lines. A single large tent can house hundreds of caterpillars, which are capable of totally defoliating host trees of wild cherry, crab apple, and other edible fruits in a matter of weeks. Oak, maple, hawthorne and willow may also be a side dish during heavy infestation.

By mid-May, most of their feeding is complete and the larva are leaving the tree looking for nooks and crannies and other hiding places to spin their yellow-white cocoons and pupate into moths. It is common to see them on your deck or on the side of the house at this time. Mating occurs in July when adults emerge and the female deposits her eggs, usually on the same tree. The life cycle is now complete having only one generation per year.

Control methods can be as simple as pruning out the egg masses or by pulling out the low growing tents with your hand and drowning the caterpillars in soapy water. Birds do like to eat them, but often cannot break through the tent. Burning the tents with a torch is not a recommended control.