These Wasps Turn Cockroaches Into Zombies, But Not Without a Fight

Image: Sharadpunita

This visually stunning insect (Ampulex compressa) is both beautiful and mesmerizing  but holds an incredibly dark secret. The emerald cockroach wasp has a fascinating parenting method and life cycle.

When a female emerald cockroach wasp is ready to become a mother, she’ll find a cockroach and sting the ganglia on its thorax. This paralyzes the cockroach’s front legs and allows her to deliver a second, more precise sting in the cockroach’s brain. This second sting disables the roach’s escape reflex, essentially transforming it into a zombie. Now, the wasp can grab the roach’s antennae and drag it off to the nearest burrow.

A jewel wasp (Ampulex compressa) attacking an American cockroach (Periplaneta Americana). Image: Dr. Kenneth C. Catania, Vanderbilt University

But the horror doesn’t stop there.

Once the roach is in the burrow, the wasp lays a single egg on the roach’s abdomen and buries the roach inside. After three days, the egg will hatch, and the baby wasp will live and feed on the roach for four to five days. Then, the baby wasp will eat its way inside the roach’s body and start devouring its internal organs.

The baby wasp will eat the roach’s internal organs in a sequence that will maximize the amount of time the roach stays alive, so it can continue to feed and grow. Eventually, it will allow the roach to die and spin a cocoon inside its body, emerging from the roach’s empty husk as an adult emerald cockroach wasp.

But it turns out that there is something cockroaches can do escape this terrible fate: aggressively fight back — often with a powerful karate kick.

Using slow-speed videography, Vanderbilt University biologist Ken Catania recorded the cockroaches’ defensive behaviors for a study published recently in the journal Brain, Behavior and Evolution. While curiously, some roaches don’t fight back at all, others deployed a number of defensive techniques.

When faced with an impending assault, the roach will assume an en-garde position, elevating its body in a “stilt-standing” posture or turning its toward the wasp, while using its antenna to track its attacker’s movements. Then, when the wasp lunges, the roach raises a spiny back leg and delivers a series of swift kicks to the wasp’s head.

Source: Vanderbilt University

And, it’s a pretty effective strategy. While the blows don’t kill the wasp, the barbwire-like spines on the roach’s leg are enough to make it reconsider. In fact, 63 percent of adult cockroaches who tried this method actually managed to escape their attackers.

Add this to the fact that cockroaches can survive for weeks without their heads, and it’s clear these insects don’t go down easy!

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