Toxic Caterpillars Are Making People Sick Across London

Forestry officials issued warnings about species of moth that are capable of causing vomiting and anaphylactic shock.

Toxic caterpillars emerging all across London.
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Forestry officials issued warnings about species of moth that are capable of causing vomiting and anaphylactic shock.

Toxic caterpillars are invading London and forestry officials are warning residents about their potential to cause vomiting, skin irritations, and even asthma attacks. The larvae of the oak processionary moth are now emerging from eggs all across southeast England, including the capital city.

According to the Forestry Commission, hair from the caterpillar contains a protein which can cause someone to get extremely sick when touched or inhaled. Used as a protection from predators, the hair can be easily picked up and carried by the wind, leading to an unsuspecting individual accidentally being exposed to it.

“At best, you can get contact dermatitis. At worst, you can die,” said Jason J. Dombroskie, manager of the Cornell University Insect Collection, as cited by the New York Times. “You can go into anaphylactic shock and have your airways close up. The airborne hairs set up a whole different ballgame.”

Every year around mid-April, the caterpillars start emerging from eggs and begin building nests consisting of “white, silken webbing” on oak trees. As they mature, a coat of thick, dense hair covers their bodies.

Every year, the Forestry Commission issues public warnings not to touch the toxic caterpillars. This year, however, the agency is taking it a step further by treating trees with biopesticides to help control the infestation.

Originating from southern Europe, these toxic caterpillars are not native to England but were accidentally brought in on imported oak plants in 2005. With no natural predators, the invasive species has continued to rapidly spread across southern Britain, particularly the London area.

So far, the caterpillar has not reached the United States. Yet, U.S. forestry and agricultural officials are keeping a close eye out for the insect, expecting it to possibly arrive hiding in imported European trees. Oak trees all along the eastern seaboard would provide the toxic caterpillar with an abundant food source and breeding ground.

“To folks in the United States, it’s not here, so don’t worry but we should continue to be vigilant,” warned Dombroskie. “We have agriculture inspectors going around, but half of the new things in the U.S. are found by the public who send it in.”

To prevent getting sick, forestry officials advise against touching the toxic caterpillars and their nests. Animals and children should not approach or disturb them.

Oak processionary moth larvae are almost always found in the spring and early summer in or around oak trees. Once they become adult moths in July or August, they generally only live for three days.