Scientists think that the Asian tiger mosquito -- one of two mosquitoes that carries Zika, dengue, and yellow fever -- first arrived in Texas in shipments of used tires in 1987. Since then, they've spread inexorably across the country.
Why they matter: The Aedes aegypti mosquito gets all the fame because it almost exclusively feeds on humans, lives in urban areas and is an effective vector for Zika and a number of other diseases. The Asian tiger mosquito (Aedes albopictus) — prefers less populated areas and is as likely to bite humans as animals, but it carries many of the same diseases and is a more effective breeder. Unlike aegypti, which can't survive harsh northern winters, albopictus has overwintered as far north as Connecticut. There are concerns that range will expand with climate change.
Data: Reported Distribution of Aedes ( Stegomyia ) aegypti and Aedes ( Stegomyia ) albopictus in the United States, 1995-2016; Map: Lazaro Gamio / Axios