Buzz
A few weeks back, I discussed the effects of recreational drugs on spiders and other animals. One fascinating detail I didn’t include was that researchers studying capuchin monkeys in South America observed them grabbing specific millipedes, crushing them, and rubbing the remains into their fur. Occasionally, this became a group activity, with several monkeys sharing a single millipede, applying it to their bodies, and passing it along. Afterward, the monkeys would drool and sometimes appear dazed. Some scientists theorized that the millipedes might have mild psychoactive properties, leading the monkeys to experience a high from their secretions.
However, when researchers examined the chemicals produced by the millipedes, they discovered the monkeys weren’t getting high—they were avoiding pests. The millipedes secreted two chemicals, known as benzoquinones, which are highly effective at repelling mosquitoes. The monkeys were essentially using the millipedes as natural bug spray. A subsequent study confirmed this by testing the millipedes’ secretions against hungry mosquitoes and a container of human blood. The mosquitoes were less likely to land and feed, and they stayed farther away when the benzoquinones were present.
Once the purpose of the millipedes was understood, a zoologist involved in the second study began offering benzoquinone-soaked napkins to capuchins at the Smithsonian National Zoo, where he worked. After a few applications, the monkeys would abandon their usual keeper and rush toward the zoologist with open arms. This reaction makes sense—mosquitoes are not only irritating but can also swarm capuchins in large numbers during the South American rainy season. Beyond the itch, mosquito bites can transmit bot fly eggs, which develop under the monkey’s skin, forming painful cysts that eventually burst, releasing maggots.
Despite how enjoyable it might seem, the side effects of using millipedes as repellent are far from pleasant. Certain benzoquinones are toxic and potentially carcinogenic, causing irritation to the eyes, skin, and mouth, which can result in a dazed appearance, excessive drooling, and discomfort. To humans, this might even give the impression that the monkeys are intoxicated. Due to these risks, researchers strongly advise against using millipedes as a DIY bug repellent. One scientist who attempted to mimic the capuchin method by crushing a millipede with his teeth experienced such intense pain from the benzoquinones entering his mouth that he dropped to his knees.
