Ants are hive animals, most species with a queen controlling everything. Within the household, they are considered pests, eating food or destroying the structure (carpenter ants). However, outdoors, they serve as scavengers to help break down decomposing life. There are several species of ants that will form a symbiotic relationship with another insect. Aphids and caterpillars are examples of this. The aphid / caterpillar will provide the ant with nectar or some sort of sugary secretion. In return, the ants will groom them. This allows for the aphids and caterpillars to have guards around them almost all the time. Research as shown that the caterpillars will secrete more of the sugary substance when they feel threatened in order to influence the ants to stick around and protect them. This protection does not extend to the caterpillar’s butterfly stage, where the ants will consider the butterfly fair game.
In terms of physiology, there are generally three classes of ants within a hive. A queen lays eggs and directs the rest of the hive. All workers are female and do most of work; scouting, scavenging, tending to the larva. The males are haploids (only ½ of DNA), and don’t do much beyond reproduce.