Insect Mouthparts There are five different structures which

Insect Mouthparts

There are five different structures which are used for the initial collection and processing of food: • Labrum - a cover which may be loosely referred to as the upper lip. • Mandibles - hard, powerful cutting jaws. • Maxillae - 'pincers' which are less powerful than the mandibles. They are used to steady and manipulate the food. They have a five segmented palp which is sensory and often concerned with taste. • Labium - the lower cover, often referred to as the lower lip. It actually represents the fused pair of ancestral second maxillae. They have a three segmented palp which is also sensory. • Hypopharynx - a tongue-like structure in the floor of the mouth. The salivary glands discharge saliva through it.

This is accomplished by having both mandibles and a proboscis. The mandibles are the paired "teeth" that can be open and closed to chew wood, manipulate wax, cleaning other bees, and biting other workers or pests (mites). The proboscis is mainly used for sucking in liquids such as nectar, water and honey inside the hive, for exchanging food with other bees (trophallaxis), and also for removing water from nectar. The workers can put a droplet of nectar between the proboscis and the rest of the mouth parts to increase the surface area, and slowly moving the proboscis back and forth.

The paired mandibles and maxillae are formed into needle-like structures (stylets) which are enclosed by the labium. When a mosquito 'bites', the pointed and barbed pair of maxillae penetrate the dermal tissue of the vertebrate to anchor the mouthparts in the tissue. This also provides leverage when the other mouthparts are inserted. The sheath-like labium slides back and the remaining mouthparts pass through its tip and into the tissue. The mosquito injects saliva, which contains anticoagulants, into the tissue to stop the blood from clotting. The labrum acts like a tongue and is used to suck up the blood.

Mouthparts are soft and end in spongy pads. Houseflies depend on their keen sense of smell, provided by their antennae. For tasting and consuming meals, the insect uses its proboscis, a plunger-like appendage that extends from the bottom of the head. Two small, antenna-like feelers called maxillary palps allow the fly to taste its food The end portion of the proboscis, called the labellum, terminates in a spongy mouth, where the fly slurps its food. It feeds only on liquids. It regurgitates part of its last meal on to its next meal. This liquid and the enzymes in it soften and liquefy part of the solid which the fly then mops up. This is another way of spreading germs. Also it frequently defecates while feeding.

Found in butterflies and some moths (Lepidoptera). The probiscis (galea) is a modification of the maxillary galea found in the more primitive madibulate (chewing) mouthparts, as seen in the cockroach. The probiscis consists of paired galea which, during feeding, fit together to form a tube that is used to suck up nectar (it acts like a straw). When not in use the proboscis is coiled and held close to the underside of the head. The Morgan's sphinx moth, Xanthopan morgani, has the longest proboscis at 30 to 35 cm in length.

Mouthpart modifications • Honey bee - the mandibles are very small and suitable for moulding wax, the labium is • curved downwards and inwards forming a tube used for sucking up nectar.

Butterflies and Moths – the mandibles have disappeared altogether. The maxillae are elongate, channelled along their surfaces and held together by hooks and spines to form a sucking tube. This proboscis may be very long, when not in use is carried coiled up like a watch spring under the head.

True bugs • these also have a piercing and sucking arrangement. The labium is elongated and acts as a sheath. This encloses the mandibles and maxillae which are modified as stylets for piercing. The maxillae have two tubes running along their length on the inside surface. 'Saliva' may be pumped down one of the tubes. This saliva makes the food into a liquid. The liquified food is sucked up the other tube.

House-fly • - the proboscis shows a capillary mechanism. The labium is elongated and forms two lobes at the tip. These lobes have a series of fine tubes (pseudotracheae). The hypopharynx runs down the proboscis and digestive juices pass down this onto the food. The food is made into a liquid by these juices. This liquid is then drawn up the pseudotracheae by capillary action.