Ants are social insects which form small to large colonies. A typical colony contains an egg-laying queen and many adult workers together with their brood (eggs, larvae and pupae). Workers are by far the most numered individuals in the nest. They are responsible for nest construction and maintenance, foraging, tending the brood and queen, and nest defence.While all workers are female, they are sterile and do not lay eggs. Winged queens and males are present in the nest for only a short period. Soon after emerging they leave the nest to mate and establish new nests. Queens are generally similar to the workers, differing primarily in having larger bodies. In some species, fully winged queens are lacking and egg-laying is undertaken either by typical workers or by individuals which are morphologically intermediate between typical queens and workers (these are called ergatoid queens). Males are generally about the same size as the workers or smaller, and have smaller heads with large ocelli, very short scapes and small mandibles. In many cases males look more like wasps than ants.Workers in a single nest can all be the same size or they can very greatly in size.