Insects have varied and interesting life cycles. In some groups, e.g. earwigs, the young nymphs are recognizably similar to the adults though they lack not only reproductive organs but also the wings that will gradually develop and finally become functional when the adult emerges from the last nymphal skin. At the other extreme are those groups, such as butterflies and beetles, which have a complete metamorphosis during a pupal stage between the larvae (adapted solely for feeding and growth) and the adults (equipped for reproduction and dispersal).

Most insects have seasonal life cycles, so it is uncommon to be able to see more than one stage of an insect at the same time. However, if nests of the Black Garden Ant are disturbed, the adult worker ants can often be seen moving the cream-coloured pupal cocoons of the next generation to safety.

In many insect species, the immature nymphs or larvae not only differ in appearance and behaviour from their adults but live in an entirely different place. Among those listed in our ‘Insect Index’ for example: dragonfly and damselfly nymphs live underwater, unlike the flying adults that rest on vegetation; Cockchafer larvae live in the soil, feeding on roots, whereas the adults fly around shrubs and trees, feeding on leaves and flowers; the caterpillars of the Red Admiral feed on nettle leaves, but the adult drinks nectar and other sugary liquids; the larvae of lacewings are predators on other insects, but the adults feed on nectar and honeydew; and the larvae of the Drone-Fly feed on rotting organic material in stagnant water, while their adults feed on nectar.

Because many insects feed on nectar, they are also very important to the life cycles of plants by acting as pollinators. However, other insect species, such as Black Garden Ants, feed on the seeds of plants and destroy them or prevent them from germinating.

In the QCA Scheme, this topic is Unit 5B for Year 5.