A "Larval Stage" leads to success
The more advanced insects, undergo structural changes that make it impossible to link the larvae with the adult forms without observing the changes for oneself. In this way maggots change to flies, grubs to beetles, caterpillars to butterflies. Since the earlier form is not required to breed, it has no sex organs and does not need to attract a mate, it needs no wings to fly, since it has probably been placed in environment that is near optimal for its development. Such larvae consume great quantities of food and therefore need efficient jaws and digestive systems. Since these larvae have no exoskeleton, the locomotion is generally slow and they have little protection against predators. This is of little consequence to grubs and maggots which live inside the tissues of plants and animals, but caterpillars which feed in the open frequently use camouflage techniques to resemble a twig, a bit of leaf or a bird dropping. Other defences may exist including squirting formic acid, having an unpleasant taste, or covering the body with unpalatable or even poisonous hairs. Some animals possessing chemical defences advertise this with a conspicuous coloration which warns potential predators of this fact. Other species with no such defences mimic the colours of those species possessing chemical defences and thereby avoid predation. The larval stage of some insects may last a considerable length of time, with grubs of beetles boring through wood for up to seven years before developing into adult forms.
Caterpillars which feed in the open frequently use camouflage techniques to resemble a twig, a bit of leaf or a bird dropping.