Caterpillars of the oak processionary moth were spotted emerging from eggs in mid-April, according to the Forestry Commission, which oversees forests in England and Scotland.
The caterpillars’ hairs, which can be released as a defense mechanism or carried by the wind, contain thaumetopoein, an irritating protein, the commission said. Those who are allergic can become sick.
“At best, you can get contact dermatitis. At worst, you can die,” said Jason J. Dombroskie, manager of the Cornell University Insect Collection and coordinator of the Insect Diagnostic Lab in Ithaca, N.Y. “You can go into anaphylactic shock and have your airways close up. The airborne hairs set up a whole different ballgame.”
British officials have issued similar warnings in years past as they have battled to stop the spread of the insect. This year, the Forestry Commission began treating trees in a “control zone” around the infected area with biopesticides, which use viruses or bacteria that mostly harm the target pest. The treatment is expected to continue through late May or early June, with trees at more than 600 sites expected to be targeted, the agency said.