Head of a parasitic wasp. Coloured scanning electron micrograph (SEM) of the head of a parasitic wasp (Aphelinus abdominalis). This tiny wasp is a parasite of potato and foxglove aphids. Its two compound eyes (green) are at right and left. At lower centre are the wasp's mouth parts, with the antennae above them. A. abdominalis is a parasitoid, a parasite that always kills its host. Females lay their eggs in the aphid's body and when the larvae hatch they feed on the aphid from the inside out. Adults also feed on the aphids, piecing holes in them and sucking out their bodily fluids. A. abdominalis is used as a biological control agent for aphids.