Of the ~100 genus (around 3500 species) of mosquitos, only a fraction bite humans and only 3 genus are responsible for most disease spread: Aedes mosquitoes (ye

Of the ~100 genus (around 3500 species) of mosquitos, only a fraction bite humans and only 3 genus are responsible for most disease spread: Aedes mosquitoes (yellow fever, dengue, and encephalitis), Anopheles mosquitoes (malaria, filariasis, elephantiasis), and Culex mosquitoes (encephalitis, filariasis, West Nile virus). All of these are invasive species to much of the world, they're only there because they were brought in by humans in the first place just like other invasives, and often fairly recently. Their spread has been further heavily facilitated by human altered environments, not just in the big picture like global warming but also more standing water, disruption of predators, and so on. And the death toll is actually quite remarkable, around 700,000 people a year die directly due to mosquito transmitted diseases.