Most insects live in constant fear of predators—but not the velvet ant. New research suggests that these gaudy, fuzzy insects are essentially invincible.

Velvet ants are actually wasps whose wingless females walk in search of other wasp and bee nests to parasitise. Though they’re slow, they’re bristling with deterrents—a tank-like exoskeleton, foul chemical excretions, and a sting so painful they’re often called “cow-killers.”

Brian Gall, at Hanover College in Indiana, wanted to see if anything can actually eat velvet ants. His …