Insect mouthparts

Most specialisation of mouthparts are for piercing and sucking, and this mode of feeding has evolved a number of times independently.

In herbivorous chewing insects mandibles tend to be broader and flatter on their opposing faces, as for example in caterpillars.

Situated beneath (caudal to) the mandibles, paired maxillae manipulate and, in chewing insects, partly masticate, food.

These palps serve as organs of touch and taste in feeding and in the inspection of potential foods and/or prey.

In chewing insects, adductor and abductor muscles extend from inside the cranium to within the bases of the stipites and cardines much as happens with the mandibles in feeding, and also in using the maxillae as tools.

To some extent the maxillae are more mobile than the mandibles, and the galeae, laciniae, and palps also can move up and down somewhat, in the sagittal plane, both in feeding and in working, for example in nest building by mud-dauber wasps.

The labium typically is a roughly quadrilateral structure, formed by paired, fused secondary maxillae.

The role of the labium in some insects, however, is adapted to special functions; perhaps the most dramatic example is in the jaws of the nymphs of the Odonata, the dragonflies and damselflies.

In many species the musculature of the labium is much more complex than that of the other jaws, because in most, the ligula, palps and prementum all can be moved independently.

[3][4][5] In the honey bee, the labium is elongated to form a tube and tongue, and these insects are classified as having both chewing and lapping mouthparts.

The hypopharynx divides the oral cavity into two parts: the cibarium or dorsal food pouch and ventral salivarium into which the salivary duct opens.

This section deals only with insects that feed by sucking fluids, as a rule without piercing their food first, and without sponging or licking.

As is usually the case with insects, there are variations: some moths, such as species of Serrodes and Achaea do pierce fruit to the extent that they are regarded as serious orchard pests.

The proboscis, as seen in adult Lepidoptera, is one of the defining characteristics of the morphology of the order; it is a long tube formed by the paired galeae of the maxillae.

Unlike sucking organs in other orders of insects, the Lepidopteran proboscis can coil up so completely that it can fit under the head when not in use.

A number of insect orders (or more precisely families within them) have mouthparts that pierce food items to enable sucking of internal fluids.