Fruit fly head. Coloured scanning electron micrograph (SEM) of the head of a male fruit fly (Drosophila sp.). Its two compound eyes (grey) are seen on either side of the head. Between the eyes are two antennae consisting of small fleshy pads with bristle-like extensions (aristas). Fruit flies are widely used in genetic experiments, particularly in mutation experiments, because they reproduce rapidly and their genetic systems are well understood. Magnification: x100 when printed at 10 centimetres wide.