Ever heard of a cricket committing suicide by jumping into water? It happens, honest. But it's not the action of a free-thinking cricket. Rather the result of manipulation by a Gordian worm, which has taken control of its host's nervous system and turned the cricket into a kamikaze zombie. Commonly known as horsehair worms, the parasite uses the cricket as an incubator for its larvae. The worm has thought ahead too, able to disembark from its drowning host by escaping through holes bored in the insect's exoskeleton. Once in the water, the worms mate, lay eggs, die and the next generation waits to be eaten by a mosquito or midge - which invariably gets eaten by the next unlucky cricket ...

Zombie cockroaches

The unsuspecting cockroach is transformed into both a nanny and a kids' restaurant by the jewel wasp. After paralysing the cockroach to prevent it from escaping, the wasp then injects venom into its victim's brain, which blocks the cockroach's ability to walk, and hinders its alertness. Essentially now a zombie, the roach follows the wasp into its underground nest. There the wasp lays an egg on the cockroach before leaving and sealing the roach underground. When the larva hatches, it eats its host from the inside out, starting with the organs. There are 200 species of cockroach wasps, all of which act as parasites on cockroaches.

Zombie spiders

Among the many types of parasitic wasps is the not-so-community-minded Reclinervellus nielseni wasp. Self-serving, it uses and abuses the Cyclosa argenteoalba spider - taking control of its mind and body to essentially make it build the nursery and become the pantry for its offspring. The female wasp lays an egg on the back of a spider and, researchers suspect, the hatched larvae inject a substance similar to a moulting hormone when it is ready to pupate. This allows the wasp to take control of its host's behaviour, making its spider slave build a cosy cocoon for its wasp offspring. After building the nursery for its ungrateful parasitic host, the spider dies, having had the lifeblood (and guts) drained from its body by the ever-growing young wasps.

Zombie caterpillars

It's not just cockroaches and spiders that should be wary of parasitic wasps. Caterpillars are also vulnerable. For the Glyptapanteles wasp, it's target is young geometrid caterpillars. The wasp lays about 80 eggs on the caterpillar. Once the eggs hatch, the larvae feed on the caterpillar's body fluids. When they are fully developed, they eat through the caterpillar's skin, attach themselves to a nearby branch or leaf and wrap themselves in a cocoon. The caterpillar, still alive, then starts to behave as though controlled by the cocooned larvae. Instead of going about its usual daily business, it becomes a bodyguard protecting the cocoon without moving away or feeding. Staying true to its masters' needs, the caterpillar stays alive until the adult wasps hatch.

Zombie ants

Ants too can go rogue, changing their regimented behaviour for the benefit of a parasitic flatworm. The worm lives in cattle and other grazing animals - so how does it make ants become zombies? Well, after mating in the liver of a cow (classy), the eggs are deposited on the grass in the animal's manure. A passing snail consumes the eggs and then deposits them in its slime. The ants are attracted to the moisture in the slime, and lap it up, swallowing hundreds of juvenile worms. Once inside the ant, the worms turn their host into a zombie by manipulating nerves, making the ant climb to the top of blades of grass, where it is more likely to be eaten by grazing sheep - and so the cycle continues.

Sources: New Scientist, The Journal of Experimental Biology, National Geographic, YouTube.