Now is the time when we should notice the silvery-gray webs of the eastern tent caterpillar on apples, crabapples, wild plum, cherry and related trees. Caterpillars emerge in late April and early May from eggs that were laid on small twigs last summer by the female moths. The caterpillars gather at a major branch fork or crotch and begin to build the silk tent.
Eastern tent caterpillars feed on tree buds and foliage on warm sunny days. The remainder of the time is spent in the protective confines of the tent. As the caterpillars feed and grow, they enlarge the tents, making them more obvious in the landscape and along roadsides.
Damage can be reduced by removing and destroying tents and caterpillars as soon as they are noticed. Tent removal should be done in early morning or late evening or on cool rainy days when the caterpillars are occupying the tents. The caterpillars and the silk webbing are harmless to people; no harm comes from taking down the tent with your bare hands, although I understand some people would rather do this operation with a pole or gloved hands.
Foliage sprays of Bacillus thuringiensis can be used if necessary.