Parasitic wasps and flies are active against the immature walkingsticks but are not efficient enough to cause a substantial population reduction. Flocks of robins, blackbirds, and grackles have a much greater impact, however. The defoliation caused by walkingsticks generally occurs on upland sites in stands which are not of high value or intensively managed. For this reason there has been little interest in control.
GYPSY MOTH, Porthetria dispar (L.)
The gypsy moth is an introduced forest insect. It was brought into this country from Europe in 1869 and has been restricted to the Northeast. The gypsy moth feeds aggressively on oak, alder, apple, basswood, willow, and birch. As the caterpillars reach maturity they will also feed on hemlock, cedar, pine, and spruce.
Gypsy moth larvae.
In the Northeast, the gypsy moth has a single generation per year, overwintering in the egg stage. Eggs hatch in late April and May and larvae are present for approximately two months. Full-grown caterpillars measure more than two inches long and are easily identified by the five pairs of blue spots and six pairs of red spots arranged in a double row along the back. The adult moths are active from late June to early September. Female moths, their bodies heavy with eggs, are unable to fly and must rely on a powerful sex attractant to lure male moths. This sex attractant has been chemically synthesized and is used as a trap bait in surveys designed to determine the presence of gypsy moths in areas suspected to be infested. Each female deposits from 200 to 800 eggs in a buff-colored mass which she attaches to any convenient surface including cars, trailers, and other vehicles.
Female gypsy moths depositing egg masses.
During the past 75 years the gypsy moth has been the target of many large-scale control programs, and much money has been spent trying to reduce the impact of gypsy moth infestations. Current control efforts are handicapped by the unavailability of a safe and effective persistent chemical. In the North two predators and nine parasites have been successfully established to help control the gypsy moth. The greatest problem in controlling gypsy moth spread, however, lies in the fact that recreational vehicles transport egg masses and larvae from infested sites into uninfested areas.