From The New York Times:
The Superorganism: The beauty, elegance and strangeness of insect societies by Bert Hölldobler and Edward O. Wilson
Hölldobler and Wilson’s central conceit is that a colony is a single animal raised to a higher level. Each insect is a cell, its castes are organs, its queens are its genitals, the wasps that stung me are an equivalent of an immune system. In the same way, the foragers are eyes and ears, and the colony’s rules of development determine its shape and size. The hive has no brain, but the iron laws of cooperation give the impression of planning. Teamwork pays; in a survey of one piece of Amazonian rain forest, social insects accounted for 80 percent of the total biomass, with ants alone weighing four times as much as all its mammals, birds, lizards, snakes and frogs put together. The world holds as much ant flesh as it does that of humans.
Karl von Frisch, discoverer of the famous waggle dance of the honey bee, said in the 1930s that “the life of bees is like a magic well. The more you draw from it, the more there is to draw.” Plenty of excellent science still springs from that source, and Wilson and Hölldobler gather some classics here. How does an ant work out how far it is back to the nest? Simple: by counting its steps. Glue stilts onto its legs as it sets out and it will pace out into the wilds; take them off and it will walk only part of the way back.
The superorganism has castes, based not on genetic differences but — like our own social classes — on the environment in which they are brought up.