ANIMALS - Ants turn unwelcome lodgers into a useful standing army

Mercenary soldiers are notoriously unreliable because their loyalty is as thin as the banknotes they get paid, and they may turn against their employers before moving on to the next dirty job. Not so in fungus-farming ants, where a new study reports that permanent parasites that are normally a chronic social burden protect their hosts against a greater evil ...

http://phys.org/news/2013-09-ants-unwelcome-lodgers-army.htm