At dusk, millions of ants throughout the world are forced to climb their way to the top of blades of grass (or flowers) and clamp on tightly. Those that survive through the morning are free to climb down and spend the rest of the day with their colony. But when evening hits again, the infected ants are stuck on the grass once again.
The zombie-like behavior of the ants is due to a parasite called the lancet fluke. The fluke makes its way to the nerves near the brain of the ant and actually takes control of the ant's movements. By controlling the ants, the fluke helps ensure the survival of its species.
The poor ants become infected by drinking snail slime. The slime trail of the snails normally provide the ants with moisture, but the slime may also contain young flukes. The zombie ants latch on to grass at dusk, precisely when cows and sheep are out grazing. The flukes force the ants to the top of grass to increase the chance of being eaten along with the grass. Once inside the grazing animal, the flukes go through the digestive tract and settle in the liver. There are no side effects seen in the larger animals. Fluke eggs are laid and excreted in the feces of the host. The circuit is complete when the snail eats the cow feces.
Zombie ants are a scary phenomenon in the natural world. They are forced to climb into prime locations to be eaten against their wills every evening. Yet the flukes give the ants control of their bodies during the day. The vicious cycle of mind control and normal behavior continues until death!
See for yourself: