There are several natural enemies that take their toll on all the stages of the gypsy moth life cycle. The insect and parasitoid species are adult ground beetles, stinkbugs, spiders, harvestmen, ants, and tiny wasps. Among the predators are mice, chipmunks, shrews, voles, skunks, raccoons, and squirrels. Bird species are orioles, starlings, robins, crows, black-capped chickadee, nuthatches and blue jays. Although this may seem like a lot of natural enemies, most can not keep up with a gypsy moth population explosion.
Black Capped Chickadee
The Virus Disease
Caterpillars killed by this virus hang in an upside-down “V” shape from trees. The bodies of the dead caterpillars liquefy and rapidly disintegrate. The virus is always present in a gypsy moth population and spreads naturally when gypsy moth outbreaks occur because they are stressed from competing with one another for food and space.
Entomophaga maimaiga: The Fungus Disease
Caterpillars killed by this fungus will hang head-down from the tree trunk, and the bodies of the dead appear dry, stiff and brittle. Within several days, the bodies fall to the soil and disintegrate, releasing the spores that will over-winter back into the soil. Like all fungi, this 1 is strongly affected by temperature and moisture. Cool, rainy weather in the spring and early summer probably favors the fungus. It was introduced from Japan in 1910 but did not take affect until the late 1980’s.