Mosquitoes are important to the environment, part of the foodchain. Fish and birds would die without them. some species only eat mosquitoes. The mosquitoes don't really kill people (unless you are unprotected in their prime breeding location\season, they can suck you dry)
its malaria. You don't even need to wipe out mosquitoes to end malaria, just wipe out the pockets of infection. And we almost eliminated malaria in the 60's; its eradication was supposed to be mankind's other great achievement, after wiping out smallpox through aggressive world-wide immunization.
large-scale DDT spraying in africa had isolated malaria to a couple small pockets but then the worlds greatest misanthrope Rachel Carson wrote Silent Spring, a horrifying tale about a world devoid of birds and wildlife because of all the chemicals we were spraying. Key to the book's success was a story about how ddt was causing eagle egg shells to thin out, and malaria only kills africans now, so why continue the eradication? SAVE THE EAGLES! Turns out theres always variability in egg shell thickness, and the whole DDT has been discounted as sloppy science, and the eagle decline was mostly due to farmers SHOOTING them for "stealin' muh chikinz" but hey, its in silent spring, and thats the eco bible right?
So, the global environmentalist movement is directly responsible for the death of every single person who dies of malaria. So evil and horrible industrialization has taken our life expectancy from 35 to 80 (in women) and good and wonderful environmentalism stopped us from curing malaria, a key factor in africa remaining the miserable place its been for thousands of years.
Wonderful.