Surprisingly few of the more than 3,000 mosquito species actually specialise in biting humans. Instead, most are opportunistic feeders – feeding when they are able and from lots of different sources. But Aedes aegypti and Anopheles gambiae are well known for their preference for human blood and their role as vectors which transmit disease in humans. Ae. aegypti has been linked to zika and dengue, while An. gambiae carries the parasite which causes malaria.