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This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

They say that the best offense¹ is a good defense². And the best defense might be the most offensive. Take, for example, the barfing caterpillars⁴ of the beet⁵ armyworm moth⁶. When threatened by marauding fire ants, these caterpillars regurgitate on their foes⁷, rendering⁸ them less able to put up a fight. But what’s so debilitating⁹ about a little caterpillar³ puke? Scientists used to think that bugs¹⁰ that protect themselves by projectile¹¹ vomiting¹² were taking advantage of chemicals they borrowed from the plants they eat—essentially spitting plant toxins¹³ 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 ooze¹⁴ 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 pesticides¹⁵ 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.

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.