Wasps: Might be scary but you can't diss an insect that can make zombie slaves out of cockroaches!

Researchers have worked out the neurological trick used by a species of wasp to turn cockroaches into 'zombie slaves'. The discovery explains why, once stung, cockroaches can be led by a much smaller master towards certain death. Researchers have proven their theory by replicating the effect, and by using an antidote injection to release the cockroaches from their zombie state.

Zombie insects might sound like the B-movie plot device from heaven (or hell, depending on your cinematic preferences). But to the emerald cockroach wasp (Ampulex compressa), they're a tried and tested way to provide food for their hungry larvae.

The wasp, which lives in tropical regions of Africa, India and the Pacific Islands, relies on cockroaches for its grisly life cycle. But unlike many venomous predators, which paralyse their victims before eating them or dragging them back to their lair, the wasp's sting leaves the cockroach able to walk, but unable to initiate its own movement.

The wasp then grabs the cockroach's antenna and leads it back to the nest. The cockroach walks "like a dog on a leash", says Frederic Libersat of Ben-Gurion University of the Negev in Israel, who led the research and has previously described the wasps' behaviour in detail. Once home, the merciless wasp lays an egg on the docile cockroach's belly, and the larva, once hatched, devours the hapless insect