When a Weaver Ant is infected by this parasitic fungus (Ophiocordyceps spp) the behavior of the ants is dramatically changed. They become erratic and zombie-like, and are manipulated by the fungus into dying at a spot that provides optimal conditions for fungal reproduction.  The growing fungus fills the ant's body and head causing muscles to atrophy and forcing muscle fibres apart. The fungus also affects the ant's central nervous system which force it to walk in a random manner, unable to find their way home.  The ant will eventually die as the fungus erupts out of its body, causing some pretty dramatic displays as above.  Entire colonies can be destroyed by this deadly fungus...  But here is good news: Ant colonies attacked by the zombie-ant fungus can survive with the help of a second parasite that castrates’ zombie-ant fungus thus keeping the infectious spores in check.(Source: www.futurity.org/top-stories/parasite-castrates-zombie-an...)   Sources: diorealskills.org/2012/09/20/social-parasites-are-as-old-...  www.biology-blog.com/blogs/permalinks/5-2011/zombie-ants-...  en.wikipedia.org/wiki/Ophiocordyceps_unilateralis