Actually, the studies show that they don't really do much in the grand scheme of things. They make up around 5% of some bats' diet, and even then, only as a last resort. You could eradicate them globally by releasing genetically modified male mosquitoes that yield 99% male offspring, rather than the correct 50/50 split. Over time, the population will die out completely because there just aren't enough female mosquitoes around. The only risk comes from that bitch mother nature throwing a spanner in the works by evolving the mosquitoes to either reverse the effect, make them able to change their sex (like snails). Or some other thing that results in super mosquitoes that are more dangerous or annoying than before. Worst case scenario, the genetic engineering results in a super virus contained in the mosquito that effects humans. That said, I say throw caution to the wind and let's kill these fuckers.