Several organisms that prey on gypsy moth caterpillars are being succesfully used to control those tree-destroying pests. They include a fungus and nematodes, as well as a virus that infects the moths. Best of all, theses gypsy moth foes don't seem to harm other, beneficial insects.
"Vanquish the Moth", Lansing State Journal, July 17, 1996, Page 6D
Gypsy moth caterpillars are a major pest that destroy many shade trees. Several control methods, which rely on organisms that prey on the caterpillars instead of pesticides, seem to be helping in the battle to preserve the trees. One such organism is a fungus, Entomophaga maimaiga, which has been used for years in Japan. This fungal pathogen has been successful in controlling gypsy moth populations in the eastern United States, and is now being tested at several sites in Michigan. The fungus is self-perpetuating and spreads by airborne spores, and therefore does not have to be spread by humans by spraying. Caterpillars become infected when they contact the fungus on the ground as they crawl from tree to tree. Because fungi grow well in damp conditions and Michigan has had a wet spring, the fungi are taking a heavy toll on the catepillars this year. In dryer years, the fungus will probably not be as successful in controlling the caterpillars.
Several other methods of biocontrol are also helping keep the gypsy moths and
caterpillars under control. Predatory nematodes, which are placed in the soil
at the base of trees, are being tested, but have the drawback of requiring reapplication
each year. A virus called NPV, which attacks the gypsy moths, also is taking
a toll on the pests. Several macroscopic organisms also prey on the caterpillars
and moths, including a ground beetle called Calosoma, cuckoos (one of the few
birds that like hairy caterpillars), and white-footed mice (which turn the caterpillars
inside-out before devouring them, apparently to avoid the fuzzy feeling in their
mouths). Most of these gypsy moth pathogens, parasites, and predators have an
added bonus; they don't seem to harm other benign or beneficial insects.