Lifecycle of a locust

Locusts undergo incomplete or direct metamorphosis. Unlike in insects such butterflies or moths, there is no pupal stage.

There are three main stages of development: egg, nymph and adult. The nymph or hopper stage can be further divided into growth stages called instars. The following diagram shows the life cycle of the Australian plague locust which has five instars during the hopper stage. The times given for development are under optimum conditions during summer and are only approximate.

Locust eggs are laid in the soil. The female drills a hole into the ground using her ovipositor and lays a 'pod' of eggs which is sealed with froth. The froth plug helps to protect the eggs from desiccation, diseases and predation.

After completing each instar the locust nymph must shed or moult its skin in order to continue to grow. On hatching the nymph is wingless but on each successive moult the developing wing buds can be seen to increase in size and can be used to determine which growth stage a nymph is in.

The final moult into the adult stage is known as fledging and is when the locust develops fully formed wings for flying. The young adult locust is called a fledgling and in most species it takes a few weeks for it to become sexually mature.

Rainfall, which produces green vegetation, is necessary for nymphal and adult survival, adult migration and/or egg development. Egg laying usually follows either migration or rainfall.

How long it takes for a locust to reach maturity depends on the species, conditions of the habitat and on temperature. In cool weather, nymphs and adults often attempt to increase their body temperature by basking in the sun.

For further details on the life cycle of the three economically important species see separate pages on the Australian plague locust, spur-throated locust and migratory locust.