Once they reach their adult size, most arthropods no longer grow. In fact, many lose weight as they moult into their final shape. This allows them to evolve more quickly to keep up with plant toxins, predators and competitors. It also allows them to take advantage of a sudden food abundance. The insects with the shortest life cycle is an aphid which takes about 5 days to produce a new generation.
Aphids are also among the most insecticide resistant insect.
These form huge swarms, flying towards areas of low pressure where rain and thus green food is likely to be. The unwinged nymphs hop along the ground behind the flying adults, until they too moult into the aggressive form. If food is plentiful, the adult form is short-winged, solitary, green, inactive and only eats grass. Often, one of the metamorphosis stages is designed for dispersal. Insects, for example, have winged adults.