From what we see now, it's very encouraging,'' said Normand Dubois, a U.S. Forest Service microbiologist leading the project at the Northeastern Center for Forest Health. That one looks pretty good,'' he said. Those sorts of words give heart to Mainers who are uneasy about chemical spraying. Dimilin, the pesticide sprayed last week over five infested islands and in Falmouth Foreside on the mainland, is controversial because it may harm lobsters and other shellfish. The pesticide acts by blocking the formation of chitin, a tough substance that gives the bodies of caterpillars their structure.
Chitin is also the stuff of which lobster and crab shells are made.
They ultimately supported the spray program because browntail moth caterpillars make people sick. Scores of Casco Bay islanders and island visitors last year had allergic reactions to the caterpillar hairs, which waft around in the air. The latest generation of caterpillars began emerging from webs early this month. Brown with a tawny fringe of prickly hairs, the larvae feed energetically on leaves and have the potential to strip acres of vegetation. During spraying last week, officials tried to keep Dimilin out of the ocean by avoiding areas within 100 feet of shore.