Toxic Caterpillars Invade London

toxic, caterpillar
Oak processionary moth larvae (Thaumetopoea processionea). The caterpillars have recently been found as far north as London, though their typical habitat is central and southern Europe. De Agostini Picture Library/Getty Images

"Attack of the Toxic Caterpillars!" could be the title of a B movie, but for Londoners, this storyline is playing out in real life.

Oak processionary moth caterpillars (Thaumetopoea processionea) have been discovered in parts of London for the first time and British forestry officials are warning people that the invasion could have deadly consequences. The moth has a white body with a wide, dark stripe along the top, and 62,000 toxic white hairs that can be released as a defense mechanism. These hairs contain thaumetopoein, a protein that can trigger allergic reactions ranging from skin or eye irritation to difficulty breathing or anaphylaxis — a life-threatening reaction to an allergen.


Even if people don't come in direct contact with the caterpillar, these defensive hairs can be picked up by the wind and cause people who are allergic to become symptomatic.

"At best, you can get contact dermatitis. At worst, you can die," Jason J. Dombroskie, manager of the Cornell University Insect Collection and coordinator of the Insect Diagnostic Lab in Ithaca, N.Y., told The New York Times.

No deaths in the U.K. have been reported, and the caterpillar has not yet been found in the U.S., where it is on a watch list of invasive insects. The caterpillars hatch in large numbers and live primarily on oak trees, where they feed on the leaves and have been known to strip trees bare. The species invaded Britain in 2005, presumably on live oak plants imported from southern Europe where the caterpillars are kept in check by insect predators, but this is the first time they have been spotted in London.