For at least 48 million years, the fungus Ophiocordyceps unilateralis has been taking over the minds of infected ants, making them desert their colonies and move to leaves that provide the ideal conditions for the parasite to reproduce.
http://www.guardian.co.uk/science/2010/aug/18/zombie-carpenter-ant-fungus
Thanks to Kebmodee for bringing this to the attention of the Its-Interesting community.
It's Interesting 