Suzanne Sadedin is one of the most interesting writers on Quora. Her answer to the question: ”Do animals fight wars and if so what was the largest war?” is both well-written and interesting:
Once upon a time there was a tiny brown ant who lived by a swamp at the end of the Paraná River in Argentina. Her name, Linepithema humile, literally means ‘humble’ or ‘weak’. Some time during the late 1800s, an adventurous L. humile crept away from the swamp where giant river otter played and capybaras cavorted.
She stowed away on a boat that sailed to New Orleans. And she went to war.
At home in the Paraná delta, L. humile nests would ferociously defend themselves from other nests, both of their own species and other kinds of ant. It was a life of never-ending territorial skirmishes, where nobody could really get ahead. When two L. humile met, they would flick their antennae over each others’ bodies, tasting the combination of hydrocarbons on their skin. This flavor would tell them whether the stranger belonged to the same nest. If she tasted familiar, she would be recognized as a sister. She would be gently stroked, offered food and welcomed into the nest. But if the flavor were not recognized, the ants would try to kill each other.
In New Orleans, something changed.