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Updated: September 28, 2017
Egg masses are deposited in July on trees, rocks, and other surfaces, where they overwinter. Eggs hatch from late April through early June, with most hatching by mid-May. Young larvae might stay near where they hatch or, by forming a long silk thread, be picked up by the wind and carried great distances. This is when orchards are invaded. The black, hairy caterpillars feed on leaves until mid-June, then pupate, molt to adults, and lay eggs.
Trees should be inspected in early June. If gypsy moths are found, they can be removed by hand and destroyed, or killed with an insecticide. Bt (Bacillus thuringiensis) or spinosad are very effective choices and least toxic to other animals.
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