Ordinarily kept in check by local predators, their recent global warming-induced migration to northern European countries such as the Netherlands and Germany has led populations to spiral into the millions, where they go untouched by birds.
Each caterpillar is spiked with up to 700,000 pointed defensive bristles, which are carried by the breeze and may provoke rashes, coughing, allergic reactions, or irritation if inhaled or touched. They nest on oak trees, marching procession-like from one to the next, and cluster together to chomp on the leaves. Their nests, which are sometimes several feet in size, are too toxic to touch.
In Germany, the Guardian reports, the caterpillar bloom has all but brought parts of the country to a halt, with swimming pools, restaurants, public parks, and even parts of the highway forced to close down. Nine children in Mülheim, Germany were hospitalized after experiencing respiratory problems and rashes after exposure on a school day, while six people in Münster had to have operations after the toxic filaments were caught in their eyes.
Eradicating the bugs is a particular challenge. Eco-pesticides used in Germany have had a limited effect, while special teams wearing protective gear have been dispatched in firefighters’ lifts to attack the nests with blowtorches or big vacuum cleaners.
In the Netherlands, a 69-year-old woman waged her own personal war on the caterpillars with a heat gun. In a now-viral video, she first flips off the insects and then burns them with the gun at close range, vowing: “I’ll tackle them, those bastards.” The caterpillars are forced out of their nests by the heat, first writhing like grubs and then falling to the ground.
But her plan of attack runs contrary to official advice. A local authority on the caterpillars advised the NL Times against taking matters into one’s own hands, especially if those hands also hold a heat gun. “If such a nest is attacked by a heat gun, there will be an explosion of hair and you can increase the problem.”