Ecology: Death Scent for Gypsies

The sight of a horde of gypsy-moth larvae defoliating a forest is one of the most urgent arguments for the use of modern pesticides. The ugly, hairy, 2-in. caterpillars eat every leaf in their path; the rustle of their ill-smelling droppings sounds like falling rain. But public ap prehension about the possible dangers of chemical insect killers is now shielding the hungry worms from DDT and other long-lasting poisons. State and federal authorities are turning with some misgivings to less controversial means of protecting the forests.

This summer’s anti-gypsy-moth campaign in New Jersey has sprayed 41,000 acres of infested forest with carbaryl, an insecticide that takes only hours to turn into inert residue. Carbaryl is therefore less effective than DDT, which stays on the foliage and kills caterpillars for weeks or months. Lest the cautious chemical fail to save the forests, New Jersey’s moth fighters also plan to drop by airplane 100,000 cardboard traps baited with a synthetic sex scent to attract male gypsy moths. New Jersey conservationists hope that when caterpillars that survive spraying turn into mature moths the males will be seduced by the scented traps and taken out of circulation. The females will then go unfertilized, and there will be no new generation of Jersey gypsy moths.