The Cordyceps fungus, also known as the zombie fungus or zombie ant fungus, is a fungus that essentially forces ants to do its bidding.
Fungal spores come into contact with carpenter ants and enter the body, they begin to release chemicals forcing the ants to behave in ways that lead to their deaths.
The fungus grows through the insect's body, draining nutrients and hijacking the brain. Over the next week, the ant will feel compelled to leave its nest and climb a plant stem. When the ant gets to a height of 25cm, the height with the exact right temperature and humidity for the fungus to grow, the ant is forced to permanently lock its mandibles around a leave.
Eventually, the fungus sends a long stalk through the head of the ant which grows into a capsule full of spores. As ants typically climb stalks near their own nests the spores fall onto other ants from the colony, zombifying them as well.