Typically, both male and female mosquitoes feed on nectar and plant juices using their elongated proboscis, but in many species the mouthparts of the females are adapted for piercing the skin of animal hosts and sucking their blood. In the latter cases, the female uses 6 needle-like mouthparts in order to suck the blood of its host. Two of these parts are called lacinae and look like microscopic saws (you can see one of them in the image above). The female uses them to cut through the skin.