The emerald cockroach wasp is an amazing example of evolution’s power to create complex instinctive behaviour. While other animals build nests, spin webs or perform dances that encode the location of a source of nectar, the behaviour that evolution has imprinted into the brains of emerald cockroach wasps is pure evil.
When a female wasp is ready to lay an egg, it finds a cockroach and stings it on the thorax, temporarily paralysing its front legs. This gives the wasp time to deliver a second sting to a precise point in its victim’s brain called the central complex. Neurotoxins in the venom block the action of the neurotransmitter octopamine which is involved in control of complex actions. The result is a disabling of the escape response, effectively creating a zombie roach unable to initiate its own actions. The wasp then leads the highly malleable cockroach to its burrow, dragging it by its antennae like a dog on a leash.
Once inside, the wasp lays an egg on the cockroach and then leaves, blocking the entrance with pebbles. The lobotomised cockroach, meanwhile, stays obediently put. Three days later, the egg hatches and the larva eats its way into the roach’s body. Over the following week, it feeds on the internal organs, leaving the most vital till last to ensure the cockroach stays alive as long as possible. It then forms a cocoon (still inside the roach), eventually emerging fully grown.
There are disturbing parallels here to Jeffrey Dahmer’s modus operandi: Dahmer temporarily disabled his victims with drugs, attempted crude lobotomies by injecting hydrochloric acid into the frontal lobe, and cannibalised various organs. However, lacking the precision derived from millions of years of evolution, Dahmer’s lobotomy attempts were dismal failures resulting in death.