As might be expected, a caterpillar s appetite increases with each moult. Feeding continues until mid-June or early July when the caterpillar enters the pupal stage emerging, finally, as a moth. Both male and female moths exist only to reproduce once with the male moths flying to find the females who are too heavy to fly. After the females lay their eggs from July to September, depending on location, moths of both sexes then die. Depending on the degree of infestation, tree damage ranges from light to almost complete defoliation.
Most deciduous trees can survive a moderate degree of defoliation.
Many can even survive one complete defoliation by the gypsy moth caterpillar. However, continuing attacks can fatally weaken a tree or leave it vulnerable to other insects or disease. The gypsy moth caterpillar is not a fussy eater. It has a preference for the leaves of deciduous hardwood trees such as maple , elm , and particularly oak . Gypsy moths can also feed on apple , alder, birch , poplar and willow trees.