Zombie ants

In the tropical forests of Thailand, there's a fungus with the scientific name ophiocordyceps unilateralis, which has a very special mechanism for spreading its spores:

It infects ants, which then change their behavior in a drastic way: The ants leave their nests, and look for areas suitable for fungal growth in terms of temperature and humidity. This phase of being controlled by the fungus lasts 4-10 days. After that, the ant dies, the fungus breaks out of the ant's head and releases spores.