[The following is an exact transcript of this podcast.]

They say that the best offense is a good defense. And the best defense might be the most offensive. Take, for example, the barfing caterpillars of the beet armyworm moth. When threatened by marauding fire ants, these caterpillars regurgitate on their foes, rendering them less able to put up a fight. But what’s so debilitating about a little caterpillar puke? Scientists used to think that bugs that protect themselves by projectile vomiting were taking advantage of chemicals they borrowed from the plants they eat—essentially spitting plant toxins at their enemies. But the beet armyworm will eat almost anything, from cauliflower to corn, and most of those plants don’t produce anything that can be weaponized.

Instead, scientists have found that these caterpillars upchuck a fluid that’s chock full of surfactants: chemicals that help make liquids easier to spread. The enhanced spreadability allows the spit-up to ooze over the surface of an unsuspecting ant, who then has to stop to clean the stuff off while the caterpillar makes his escape. The results were published by the Royal Society on November 5th. Some pesticides rely on surfactants to protect crops. So biotech companies might look to the caterpillar when they need some fresh ideas to throw up on the board.

—Karen Hopkin 

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