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lar to Pennsylvania.”
Mr. Morris believes that the release of parasitic organisms is “the most worthwhile single effort to control gypsy moths. But,” he adds, “outbreaks will still occur even under the best of conditions conducive to parasite establishment.”
Furthermore, according to Mr. Morris, parasite establishment is not something we can do to prevent initial invasion and defoliation by gypsy moths. “Because of insufficient numbers of the host animal (gypsy moths), it’s just not possible to establish parasites in advance of defoliation,” he said.
Based on its research and experience, Pennsylvania’s Department of Natural Resources is beefing up its parasite establishment program. One such parasite is known as the “Friendly Fly” — so named because of its apparent delight in landing and resting on (but not biting) human beings.
James 0. Nichols, chief of Pennsylvania’s Division of Pest Management, said that under optimum conditions, “these flies can cause 70 percent-plus kill, and a population collapse.”
At a recent forest management workshop at Front Royal, Mr. Nichols offered some advice on chemical insecticides: “A decision to spray timber must carry with it the realization that repeat sprayings may be necessary at two to three year intervals indefinitely, especially if tracts over 1,000 acres are involved. This has been borne out during Northeastern spray operations over the last 40 years.”
Mr. Nichols explained that since 1982, Pennsylvania has discontinued chemical sprays altogether. Bt, the bacterial spray, is the only material presently used. “Objectors” — those landowners who don’t want their property sprayed with chemicals — can seriously disrupt aerial spraying of suiTounding areas, Mr. Nichols said.
“Objectors” are the major reason for Pennsylvania’s new spray policy, said Mr. Nichols. But “Bt works well enough. We can usually get 70 percent to 90 percent kill, which is sufficient to keep the trees green and the people happy.”
In professional circles, the gypsy moth is often referred to as a “people problem” and a “political insect.” The demands of the people — as well as the anticipated biological response of the insect itself — will determine a community’s choice of control measures. Because there are no happy solutions to the gypsy moth problem, there will always be disagreement and controversy.
But one common message from our government agencies is clear Virginians should observe and learn from what’s happening in New England, where the gypsy moth has been around for more than 100 years.
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