I’ve started reading an E.O. Wilson book (can’t remember the name and it’s not nearby) and it has already imparted an interesting fact: Ant species sometimes kidnap young ants of other species and force them into slavery. This site provides some interesting details.

Humans aren’t the only species that have had to deal with the issue of slavery. Some species of ants also abduct the young of others, forcing them into labouring for their new masters. These slave-making ants, like Protomagnathus americanus conduct violent raids on the nests of other species, killing all the adults and larva-napping the brood.

When these youngsters mature, they take on the odour of their abductors and become the servants of the enslaving queen. They take over the jobs of maintaining the colony and caring for its larvae even though they are from another species; they even take part in raids themselves.

Youtube even has a video, though I’m unclear of the source and why the people in it are wearing historical garb.