Cockroaches Karate-Kick Wasps to Avoid Becoming Zombies


This roach is kicking butt and taking names — of wasps. HowStuffWorks

It sounds like something out of a horrifying science fiction film. An aggressive winged insect shoves its stinger into its victim's brain, using neurotoxin venom to turn it into a docile, zombiefied husk that it then "walks" to a burrow in the ground. The hole is sealed ... and so too is the fate of the victim, which is slowly consumed by the attacker's larvae.

This isn't fiction; it's what happens when emerald jewel wasps sting American cockroaches and turn them into walking buffets for their offspring. Jewel wasps have a multiple-sting technique, starting with a first attack that paralyzes the roach's legs. The second assault rams the stinger through the roach's throat and into very specific parts of the target's brain.

The wasp's stinger is so sensitive that it can (nearly instantaneously) feel around inside the roach to locate the proper brain structure, at which point it unleashes its chemical attack, initiating the zombification process. The wasp later embeds its eggs in the roach, and the cute baby wasps devour the roach from the inside out, scrambling their way out of the roach's lifeless body a few days later.

But it turns out that the roaches don't go willingly into the night of the living dead – they often use potent karate kicks to keep the wasps at bay.

Ken Catania, a neurobiologist at Vanderbilt University, was curious how roaches attempted to protect themselves from a wasp's nefarious assaults. He documented attacks with high-speed video recordings and then reviewed them in slow-motion. Then, he realized that the roaches were doing their best Bruce Lee impressions, unleashing vicious kicks that frequently warded off the wasps.

When a wasp approaches, the roach goes on alert. "That allows the roach to move its antenna toward the wasp so it can track an approaching attack and aim kicks at the head and body of the wasp, and that's one of the most efficient deterrents. It's reminiscent of what a movie character would do when a zombie is coming after them," said Cantina in a university press release. The study was published in the journal Brain, Behavior and Evolution.

Because adult cockroaches are six times larger than the wasps, their large, spiky legs make for effective striking weapons. Cantania's research demonstrated that the defensive kicks were effective 63 percent of the time, so long as the roach could keep up the oji waza (countering technique) for about three minutes. Immature cockroaches, on the other hand, were more often felled by the wasps, doomed to short lives that ended in horrifying fashion.


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