>>2210071Because they're gross, bite, carry diseases, and they always fucking bother you and attempt to use your body for food, shelter, reproduction, etc. With rare exception, they're all pests. Compared to the total amount of terrestrial arthopod species, there are scant few beneficial species, and most are just out to fuck with mammals and make the world an annoying place to hang around in. It's to the shame of our civilization that we haven't exterminated all mosquitos yet. The planet will figure out a new balance without them, millions of people won't die from horrible diseases, animals won't live miserable lives during mosquito seasons, and I can finally sleep by the lake without being fucking eaten alive.
