Ants even keep plant lice as pets. They feast on the sugary feces that the lice discard. In return, the ants defend the lice against enemies. However, there are researchers who say this is less a symbiosis and more like slavery. The ants keep the herds of lice together through the use of force.
When an ant is injured in a fight, it excretes chemical substances. This is a call for its mates, who will carry the injured insect back to the nest, where it can recover. A German research team of the University of Würzburg have observed this rescue behavior for the first time.