The larva's appearance is generally very different from the adult form (e.g.caterpillars and butterflies). A larva often has unique structures and organs that do not occur in the adult form, and may have a considerably different diet.
Larvae are frequently adapted to environments separate from adults. For example, some larvae such as tadpoles live exclusively in aquatic environments, but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population.
The Pine Processionary(Thaumetopoea pityocampa) is a moth of the family Thaumetopoeidae. It is sometimes placed in the genus Traumatocampa. It is an abundant species found in pine woods in central and southern Europe, and an important economic pest. The species is notable for the behaviour of its caterpillar larvae, which overwinter in tent-like nests high in pine trees, and which process through the woods in nose-to-tail columns, protected by their severely irritating hairs, as described by the pioneering entomologist Jean Henri Fabre.