Larval Forms

caterpillar showing prolegs and true legsladybird larva with six legs

Larvae are adapted for consuming food and growing in size in preparation for the adult stage - they are "feeding machines". Larvae become larger at each moult and the size of the adult is determined by the size of the larva prior to pupation. For example, many people assume that a small house fly is a young fly that has not yet completed its growth. However, the size of the fly is actually a reflection of the amount of growth attained by the larva. The size of the adult is therefore largely dependant on the on the food supply available to its larval form.

Larval forms are very different from their respective adult forms. While all adult insects have 6 legs, the number of legs present in their larval forms varies. Photo 1 shows a caterpillar, an example of a polypod larva - it possesses 3 pairs of jointed legs (true legs) and numerous abdominal prolegs. The true legs will become the legs of the adult and the prolegs will disappear during metamorphosis. Photo 2 shows a ladybird beetle larva, an example of an oligopod larva. It possesses only 3 pairs of jointed legs, which, like the polypod larva, will become the legs of the adult.

Photos courtesy of Keith Power, Toowoomba, Qld.