Life cycles of a grasshopper and a moth. Then from the egg, a small immature insect emerges. Depending upon the group to which it belongs, it will be either a larva or a nymph, but it may be called by various names. For instance, the larvae of the familiar butterflies and moths are often called caterpillars. Larvae of flies are called maggots, those of some beetles are grubs, and juvenile mosquitoes are known as wrigglers.
Crawlers are the pinpoint-size nymphs of scale insects.
The aquatic nymphs of dragonflies are known as naiads. As the immature larva or nymph feeds and grows, it enlarges by shedding its rigid outer skin called an exoskeleton. Every time it does this it changes to a new stage called an instar. The first instar emerges from the egg and deve lops to the first molt. Most common insects have 3 to 6 instars.