Termites are one of the longest living insects in the world, but this only applies to the termite queen, which in some species, may live for a decade or even more. The typical termite worker or soldier has a lifespan of about 1-5 years, but this depends a lot on the species and the environment it is in.
Termites are one of the insects that undergo incomplete metamorphosis, which is a major difference from the other eusocial insects, namely ants, bees, and wasps, which undergo complete metamorphosis.
To explain all these in simpler terms, in incomplete metamorphosis, the juvenile which hatches from the egg will show a lot of similarities to its adult appearance, and through a series of molts or instars, will gradually get bigger with each stage and assume its adult appearance gradually. Ant babies, who undergo complete metamorphosis, look exactly like grubs when they first hatch from their eggs and referred to as, “larvae.”
Termite babies are often called “larvae,” but it is perhaps more correct to call them nymphs, since larvae is associated with a grub-like appearance. Even when first hatched, termite nymphs bear a lot of resemblance to the adult workers tending to them. Termite nymphs are very mobile; especially those in advanced instar stage. They can move about the nest at will, although they are not able to perform any duties and need frequent care from the workers.
The typical worker termite has a life cycle which can be divided into 3 stages:
The egg cycle lasts approximately almost a month, the nymph stage lasts about a month (in temperate climates this may be more), and the adult stage would be about one to several years, as described earlier. This may vary from species to species, and also depend on external environmental factors.
Some pictures of termite nymphs
The worker nymph stage usually consists of about 7 molts or instars, in which the nymph gradually assumes its adult morphology. They cannot molt successfully, unless aided by adult worker termites, which help them shed their outer skin by chewing it off. However, some types of drywood and dampwood termites are able to molt without assistance.
The soldier nymph requires an extra few more molts (pre-soldier instar) before attaining maturity. Once becoming soldiers, they cannot revert back into the worker stage again (terminal molting). Reproductives (fertile males and females) have a longer nymph stage than the other castes; hence more molts lasting several months.
All castes originate from the “basic” worker instar, and their numbers are controlled by circulating pheromones in the colony, and external factors, like food supply and current caste population. For example, if many soldiers perished in combat with ants, the pheromone imbalance would work to restore the soldier population balance in the colony.
Termites can undergo regressive molts, which happens in alate nymphs, reverting them back to the worker stage, although this phenomenon seems mainly to occur in drywood/dampwood termites, and happens when the current reproductives of the colony release pheromones that prevent the nymphs from developing into reproductives themselves. The nymphs then lose their wing buds and turn back into workers.
In those species that are able to produce secondary reproductives in the absence of the queen and king (like some drywood termites), workers may turn into reproductives capable of breeding and continuing the colony. So in these cases, workers who turn into secondary reproductives would have a major lifespan extension compared to the ordinary workers.