I think we already had one... back in the 60's. DDT use was widespread worldwide. My Dad even used it at our cottage... best summer ever, next to no mosquitoes. Unfortunately DDT has a big impact on birds... softens the eggshell such that eggs don't hatch/grow. DDT is outlawed in a lot of places... but by no means all.

We almost won the war on mosquitoes but our allies the birds would have been wiped out if we'd kept fighting :)