Bat flea. Coloured scanning electron micrograph (SEM) of the underside of an Ischnopsyllus octactenus flea, showing its mandibles, which are used to pierce the host's skin and suck blood. This flea lives on the common pipistrelle (Pipistrellus pipistrellus) bat. As a result of living on a nocturnal host the flea has no eyes. Magnification: x160 when printed 10 centimetres wide.