<P> A number of insect orders (or more precisely families within them) have mouthparts that pierce food items to enable sucking of internal fluids . Some are herbivorous, like aphids and leafhoppers, while others are carnivorous, like assassin bugs and mosquitoes (females only). </P> <P> The defining feature of the order Hemiptera is the possession of mouthparts where the mandibles and maxillae are modified into a proboscis, sheathed within a modified labium, which is capable of piercing tissues and sucking out the liquids . For example, true bugs, such as shield bugs, feed on the fluids of plants . Predatory bugs such as assassin bugs have the same mouthparts, but they are used to pierce the cuticles of captured prey . </P> <P> In female mosquitoes, all mouthparts are elongated . The labium encloses all other mouthparts like a sheath . The labrum forms the main feeding tube, through which blood is sucked . Paired mandibles and maxillae are present, together forming the stylet, which is used to pierce an animal's skin . During piercing, the labium remains outside the food item's skin, folding away from the stylet . Saliva containing anticoagulants, is injected into the food item and blood sucked out, each through different tubes . </P> <P> The housefly is the typical sponging insect . The labium gives the description, being articulate and possessing at its end a sponge - like labellum . Paired mandibles and maxillae are present, but much reduced and non-functional . The labellum's surface is covered by minute food channels, formed by the interlocking elongate hypopharynx and epipharynx, forming a proboscis used to channel liquid food to the oesophagus . The food channel draws liquid and liquified food to the oesophagus by capillary action . The housefly is able to eat solid food by secreting saliva and dabbing it over the food item . As the saliva dissolves the food, the solution is then drawn up into the mouth as a liquid . </P>

Diagram of a mouth part of a butterfly