Most people don't like bug shots, so if you're one of them, don't click to enlarge the photos below. I don't like to photograph bugs myself, but in this case, i'm making an exception.
I've only read about the symbiotic relationship ants have with aphids. The former herd the latter like cattle and protect them like sheep. They move aphids around to the most succulent branches and keeping the aphid's natural predators at bay.
In return, the aphids produce drops of sweet liquid that the ants collect and bring home to feed the colony. Isn't it amzaing how one specie instinctively knows it can't survive well without the other? If only people understood that relationship as well as they do! Enjoy!