Where I live the KABS (https://en.wikipedia.org/wiki/German_Mosquito_Control_Associ...) is very effective at reducing mosquito populations: "At a cost of 400k€ annually the result is a reduction of the mosquito population by 99% compared to untreated areas", and 95% of total mosquitoes in the larger area. They use proteins produced by a bacterium (Bacillus thuringiensis israelensis) to kill the larvae. It's fantastic, their work improves quality of life significantly.
There has been a separate research effort to develop mosquitoes that are genetically modified rather than bacteria-infected, with similar objectives, that so far has been stymied in the US by a combination of stronger regulatory hurdles (since it's regulated by a different agency) and NIMBYism. Oxitec is the company spearheading that research. See, e.g., http://www.npr.org/sections/health-shots/2016/11/20/50271725...
