caterpillar - Anatomy, Defense, Behaviour, External features of a caterpillar, Photo gallery

The larval stage of butterflies and moths (Order: Lepidoptera), usually feeding on plants; occasionally also used for the larvae of sawflies (Order: Hymenoptera).

For the industrial equipment manufacturer, see Caterpillar Inc..

A caterpillar is the larval form of a lepidopteran (a member of the insect order comprising butterflies and moths).

Anatomy

Caterpillars have long segmented bodies. Sawfly larvae (Hymenoptera) superficially resemble caterpillars, but can be distinguished because they have prolegs on every abdominal segment, whereas the true caterpillar does not. Thus, true caterpillars always have a few abdominal segments lacking prolegs, in some cases several, or even all segments may lack them.

Both caterpillars and sawfly larvae have soft bodies that can grow rapidly between molts, like a balloon.

Like all insects, caterpillars do not breathe through their mouths.

Caterpillars do not have very good eyesight. The larvae of sawflies differ from true caterpillars in this respect, as well, as they have prominent ocelli on the head capsule.

Some caterpillars are able to detect vibrations, usually at a highly specific frequency. Caterpillars of the common hook-tip moth, Drepana arcuata (Drepanoidea) produce sounds to defend their silk nests from members of their own species (Yack et al., 2001) by scraping against the leaf in a 'ritualized acoustic duel.' They detect the vibration of the leaf, not air-borne sounds.

Defense

Many species of birds and animals consider caterpillars as protein rich food, and caterpillars have evolved various defenses.

Some caterpillars will regurgitate acidic digestive juices at attacking enemies.

More aggressive self-defense measures are taken by hairy caterpillars. The most aggressive defenses are those of the many caterpillars that have bristles associated with venom glands, called urticating hairs, and one of these is among the most potent defensive chemicals in any animals;

Some caterpillars eat the leaves of plants that are toxic to other animals. These toxic species, such as the Cinnabar moth (Tyria jacobaeae) caterpillars, are brightly striped or coloured in black, red and yellow—the danger colours (see aposematism).

The aim of all these aggressive defense measures is to assure that any predator that eats (or tries to eat) one of them will avoid future attempts.

Some caterpillars obtain protection by associating themselves with ants.

Behaviour

Caterpillars have rightfully been called eating machines.

Caterpillars are predominantly herbivores: 99% of species feed on plants (Pierce, 1995).

External features of a caterpillar

1 - Head; 9 - Antenna

Photo gallery

Cup Moth	Cup Moth on bicycle wheel	Caterpillar	Xylena exsoleta
Xylophanes tersa	Pale Tussock Moth Caterpillar	Caterpillar	A file of processional caterpillars
Woolly Bear	Polyphemus moth	Caterpillar	A Swallowtail caterpillar on a branch of keffir lime tree
A pair of Eastern Tent Caterpillars	Caterpillar	Caterpillar of Saturnia pavonia (Emperor Moth)	Bedstraw Hawkmoth larva (Hyles gallii)
Caterpillar	Caterpillar	White-marked tussock moth	Papilio aegeus