Insects that use their mouths primarily for biting or chewing consist of four basic categories: (1) predators that chew prey, (2) herbivores that chew plants, (3) males combating other males and (4) workers that cut, carry and build. The main mouthparts include (1) jaws or mandibles that chop and chew food into pieces or that cut wood and dig soil, (2) maxillas that hold food and assist the mandibles, (3) maxillary palp and labial palp that taste the food and (4) the labium or the lower lip.
The carpenter bee uses its large mandibles to chew through wood, building tunnels and nests in the wood. The stag beetle has larger pincerlike mandibles that it uses for fighting other males for territory. The paper wasp chews insects for food. Other insects with biting mouths include dragonflies, termites, ant lions, lacewings, beetles, wasps and bees.
Insects in this group usually have a complex tube (known as a proboscis or rostrum) that they use for sucking. This highly modified, tubelike mouth uses stylets to pierce the outer skin of plants or prey and to suck the sap or blood. There are two stylets, mandibular and maxillary, and the tips are usually barbed for piercing. Inside the stylets are two canals, the food canal and the salivary canal. All of this is surrounded by a segmented labium that acts as a protective sheath around all the canals and stylets. The labrum covers the stylets and labium at the base. When the tips of the stylets penetrate the plant or animal tissue, a strong pump muscle in the head becomes activated, inserting saliva into the host plant/animal through the salivary canal and sucking up liquid through the food canal. When not in use, the labrum, labium and stylets fold flat and tuck in under the head and abdomen.
Butterflies suck nectar from flowers, mosquitoes suck blood from animals and leaf-footed bugs suck plant sap. The mouth of a horsefly is another example, but it is a bit more complex in that it cuts the skin of animals (not bites), causing it to bleed and then sucking the blood. Other insects include true bugs, cicadas, aphids, moths and flies.