I personally think they are here for more food for bats, frogs, and birds to eat. (altough I don't see why they don't have enough bugs already to chomp on)
The funny thing is people always assume that mosquitoes suck blood as a main food source, even though thats not true. The females suck blood once to have enough extra nourishment to produce eggs. The males (the ones who make the annoying buzzing sound) don't even bite at all.
florglee2 youre an idiot if you think that animals are just here if there were no cows no more milk,cheese,ice cream,beef,burgers, no cows means none of their natural predaters would survive if there wer no bees we wouldnt have flowers;no birds=no trees; no trees= no oxygen;no oxygen means no life!
PS:this isnt a full breakdown of what would happen.
Well, because all life evolves. They may seem here for no reason, but mosquitos will evolve into something more useful. But for now, they have no point except for food for frogs, and spiders.