Asian tiger mosquito (Aedes albopictus), coloured scanning electron micrograph (SEM). Structures on its head (upper centre) include its large compound eyes (red), two feather-like antennae, and a long proboscis (down centre). This mosquito acts as a vector for the West Nile virus and the Dengue fever virus, which it transmits when it feeds on blood. Both of these cause diseases that can be fatal. This mosquito originated in Asia, but it has been introduced to tropical and subtropical regions around the world.