The most interesting feature about the emerald jewel wasps is what they do when they reproduce they zombify a cockroach. The female wasp will first find a cockroach, when she finds it she will carefully approach the cockroach. The female wasp is much smaller than the roach, afterall. When she gets close enough, she will sting the cockroach on its thorax. The first sting paralyzes the bug’s front two legs which allows the wasp to make its second move. The wasp will then sting the cockroach in its ganglia (insect equivalent of a brain). The wasp’s sting is very precise because the stinger is able to sense where it is inside the roach’s dome. After this second sting the cockroach will start to compulsively clean itself for thirty minutes while the wasp waits nearby or finds a good space to make a burrow. Scientists have shown this compulsive grooming is because of the venom injection. By this time the cockroach is in a zombie-like state and its front legs are no longer paralyzed. It’s still alive but it has lost it’s escape reflex, making it easier for the wasp to do the next step.
She will then sever the roach’s antenna by vibrating her wing muscles. She then drinks its blood for nutrients. Scientists think that she can tell how effective her venom is by the taste of its blood. Too little means it’ll snap out of the zombie like state and too much means it will die too quickly. After drinking the blood, the wasp will walk the roach by the other antenna to the burrow she’s dug. She then lays a single egg on the roach’s leg and takes thirty minutes to block the entrance with debris. This isn’t to keep the roach from escaping, he’s lost all will to flee, it’s to keep predators out.
An interesting thing about the venom is that it’s temporary. It only lasts for about a week, but by then the roach is dead. The venom also slows down the roach’s metabolism so it stays hydrated, fresh, and alive for the wasp’s young to feed off of. Perhaps the most interesting thing about the venom is what it does to the roach. The sting to the ganglia injects a lot of GABA into the roach’s brain which acts as a neuron inhibitor. This neuron inhibition cuts brain activity that would make the roach flee. The venom does not, however, affect the motor abilities of the roach. The roach can still move and do things like flipping over, it just doesn’t want to. Scientists have shown that touching a wing or a leg still sends signals to the insect’s brain, it just doesn’t evoke a behavioral response. That’s why the roach is so okay with being led to an underground burrow and being eaten alive.
The larva will hatch after three days, the first instar stage larva eats the base of the leg of the cockroach and drinks its blood. After 4-5 days the larva begins to eat the roach’s abdomen while still feeding on the blood in the second instar. Then the larva will start to eat the alive roach’s internal organs in the final instar. This kills the roach and the larva now prepares for its pupal stage. It will make a cocoon inside the roach’s dead body. The cocoon is made from silk and it has two layers. One layer is a hard shell and the other is a thickly woven silk covering for the shell. Male wasps have lighter and smaller cocoons than females because the females are larger. The larva stays in the cocoon for a few weeks and then it emerges as an adult emerald jewel wasp, and it’s ready to continue the zombifying cycle.
“I don't know if cockroaches dream, but I imagine that if they do, jewel wasps feature prominently in their nightmares.” - Christie Wilcox