Mindsuckers: Meet Nature's Nightmare

The world is full of parasites: mindsuckers that spread their genes by hijacking a host and turning it into a real-life zombie. The November issue of National Geographic magazine investigates the secret lives of these creatures and the lessons they hold about evolution and behavior in the natural world. Images by photographer Anand Varma show the fate of some of the parasites' unfortunate hosts.

Click here to meet the mindsuckers.

Click here to read a Q&A with Varma about capturing these images.

Click here to read about parasites online in National Geographic magazine.

The parasites: 
Horsehair worm (00:00) 
Larvae of the parasite infiltrate the cricket when it scavenges dead insects, then grow inside it. The cricket is terrestrial, but the adult stage of the worm’s life cycle is aquatic. So when the mature worm is ready to emerge, it alters the brain of its host, driving the cricket to abandon the safety of land and take a suicidal leap into the nearest body of water. As the cricket drowns, an adult worm emerges, sometimes a foot in length. 
Parasitic flatworm (00:30) 
After the flatworm Ribeiroia ondatrae reproduces asexually inside a snail, its larvae find a bullfrog tadpole and burrow their way through its skin, forming cysts around the frog’s developing limbs. With legs added, subtracted, or compromised, the ungainly victim is easy prey for frog-eating birds like herons. Inside the heron, the parasite reproduces sexually. Its eggs reenter the water when the bird defecates, infecting new snails to start another round. 
Parasitic wasp (00:48) 
When a female Dinocampus coccinellae wasp stings a ladybug, it leaves behind a single egg. After the egg hatches, the larva begins to eat its host from the inside out. When ready, the parasite emerges and spins a cocoon between the ladybug’s legs. Though its body is now free of the tormentor, the bug remains enslaved, standing over the cocoon and protecting it from potential predators. Some lucky ladybugs actually survive this eerie ordeal. 
Parasitic barnacle (01:00) 
A male sheep crab infected by a parasitic barnacle is literally feminized. It stops developing fighting claws, and its abdomen widens, providing a “womb” for the barnacle to fill with its brood pouch. Nurtured by the crab, the eggs hatch. Thousands of baby barnacles disperse to infect anew.