The head has projecting mouthparts with chewing mandibles. Caterpillars lack the proboscis and have separate chewing mouthparts. Mandibles are absent in all except the Micropterigidae which have chewing mouthparts. The mandibles are short, and the mouthparts unspecialised. Insect mouthparts and antennae are considered homologues of insect legs. Maxillipeds are appendages modified to function as mouthparts. Many mouthparts and associate structures (such as pedipalps) are modified legs. The head has five pairs of appendages, including mouthparts, antennae, and antennules. The head segments bear various mouthparts and two pairs of antennae. The labium encloses all other mouthparts like a sheath. These insects are recognisable as tabanids both from their mouthparts and their wing venation. These sexual aphids may lack wings or even mouthparts. Adults have vestigial mouthparts and do not feed. It controls the mouthparts, the salivary glands and certain muscles. The mouthparts of these insects are adapted for predation.