Rubbing their legs is a vital piece of fly behaviour – grooming. Though many insects appear sleek and shiny, they can only maintain this level of cleanliness by constant preening and careful removal of dirt, moisture, pollen and anything else that might stick to their bodies.
Smears of grime or pieces of grit can easily interfere with flight or movement through grass, and provide a foothold for potentially deadly moulds and fungi to attack.
Even insects that breed in ‘filth’, such as bluebottles, must keep themselves in tiptop condition. Legs are the main cleaning tools, and are often covered with bristles to sweep the head and wings clean. Front legs may have a distinct notch or groove especially for wiping the antennae to keep them squeaky clean.
Most other parts of a fly’s body are also coated with hairs and bristles. These are loaded with receptors around their bases, making them touch- and movement-sensitive. Used to detect air currents and monitor body position, they need to be kept spick and span to ensure a fly’s optimum performance.
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