Rain washes toxic oak processionary hairs from the air

Heavy rain in Odense and surrounding areas is disrupting the spread of the oak processionary moth, often called the “larva from hell,” according to a report from DR.

Biologist Bjarne Skule, a butterfly expert, said the microscopic, toxic hairs shed by the caterpillars cannot remain airborne in wet conditions. Instead, they are washed out of the air by rainfall.

“I think this rainy weather is very good news,” Skule told DR. “There’s no doubt that these tiny toxic hairs, which are just a tenth of a millimetre long, like other airborne particles, are flushed out of the air by the rain—especially if it’s heavy.”

The hairs, which cause rashes and itching, have spread widely in recent dry, warm weather, affecting residents in Odense SØ, Munkebo, and nearby areas. Local authorities have closed three trails, a daycare centre, and a recycling site as a precaution.

Skule added that the first downpour clears the air, and continued rain should prevent new hairs from becoming airborne.