Termites live in well structured social systems, much like ants. There is a queen, a king, workers, and soldiers. Some species may have several queens and kings, but generally, the typical termite colony is ruled by a single queen and a male king, while the rest of the workers and soldiers are sterile males and females. Unlike other social insects like ants, wasps, and bees, termites have both genders in the worker and soldier caste.
Besides the castes described above, there are also winged reproductive males and females, (also called alates), which are created in the termite colony from time to time. They swarm out from the colony when fully grown and outside conditions are right. Then there are the juvenile nymphs in various stages of development (termites develop by shedding their skins), otherwise known as incomplete metamorphosis.
Baby termites hatch from eggs looking just like adults, except that they are almost transparent in color, almost pure white, and as they acquire bigger size with each molting, they shed their exoskeletons but never really change their morphology significantly. In contrast, ants hatch from eggs as grub-like larvae, and then undergo complete metamorphosis with each molt to eventually turn into ants. The same goes for bees and wasps.
The queen termite is an egg laying machine that can lay up to 10,000 eggs a day, depending on species. She serves as the main source of pheromones in the termite colony, which binds the entire colony together and these pheromones are spread through termites feeding one another (trophallaxis).
The king on the other hand, is merely the queen’s consort, and in the termite world, his job is to mate periodically with the queen so that she can keep producing more fertile eggs. Unlike ants, in which the males die off after mating with the females (and ants only need to mate once), the queen termite needs periodic fertilization. The termite king looks no different from a typical flying reproductive termite, except minus the wings.
Termite colonies can attain a large size (up to a couple of million in a few species) but termite colonies are still smaller than some species of ants (like army ants) which may be 5-20 million strong! Most termite species do not exceed a few hundred thousand individuals per colony, and many rainforest termite colonies do not exceed 100,000 individuals, based on many studies.
The most abundant individuals in the termite colony would be the worker termites, followed by the soldiers and nymphs. While the queen and king are usually indispensable to the functioning of the colony, some species are able to replace them by turning some nymphs into reproductive males and females, should the need arise.