Larvae can receive different names in different animal species. Larvae of crustaceans species are called zoea or nauplius, while the larvae of butterflies and moths are called caterpillars. Amphibians, such as frogs, also pass through a larval stage, when they are called tadpoles. Bipinnaria is a larva that will become a starfish, whereas a glochidium becomes a freshwater mussel and a wiggler is the larval form of a mosquito. Maggots are fly larvae and a grub often refers to the larvae of Scarabaeoidea beetles.
Larvae live in diverse habitats, include fresh and salt water, soil, decaying material and as parasites of plants and animals. The lifespan of a larva varies according to the species. The larvae of monarch butterflies have lifespans of about two weeks, while other butterfly and moth species can live as a larva for a single week to as long as six weeks, in the case of the moth Actias luna. Most maggots live for up to eight days, while wigglers last from one to two weeks, depending on water temperature. Bigger animals, such as frogs, have longer larval stages, from about five to nine weeks.
Some larvae feed mainly on leaves and other plant parts, including most butterflies and moth species. Tadpoles feed on algae and plants, but some species also eat smaller larvae and other organic materials. Maggots often eat carrion and decaying organic materials while many species of insects live as parasites on animals and plants during their larval stage. Larvae can also be active hunters and even cannibals, such as the fungus gnats of the genus Arachnocampa, which feed on other larvae and adults of the same species.
Larvae are notorious agricultural plagues. The yellow butterfly Colias eurythemeis is an agricultural plague, which is better known through its larval stage as the alfalfa caterpillar. The larva of the oak processionary moth is one of the many species of toxic caterpillar, which can cause skin irritation if touched. Species of flies from the genus Drosophila lay their eggs in fruit, causing larval infestation and destroying crops. However, larvae are also beneficial to humans. Braconidae wasps lay their eggs on or into caterpillars that are agricultural plagues, causing their death. The larva of the moth Bombyx mori produces silk, and is also called the silkworm.