The head of the fly contains the eyes, antennae and mouthparts. The common housefly liquefies food with its saliva before the mouthparts are used in a sponging, mopping capacity. The antennae provide flies with their primary source of smell and often are different between males and females. The housefly's compound eyes are some of the most complex of the insect world, allowing them to see a significant radius around their body. This makes flies difficult to surprise or swat.
Flies have a pair of fully developed wings on the thorax, and a knobby, vestigial second pair of wings, called halteres, that are used primarily for balance. The fly's six legs also connect to the thorax and are made of five segments. The housefly has a hard exoskeleton that protects it from moisture loss. Houseflies use the hairs on their bodies to taste and to smell.