Mosquitos

They serve no purpose. Their contributions toward human population control and as food for other animals is really not that significant in the grand scheme of things. Their predators feed off of plenty of other sources. They are irritating and are probably the most hated creatures alive. The females are the ones that suck blood, and they don't even need it to survive. Mosquito larvae prey on their fellow mosquito larvae. How more despicable and unlikeable could they get? Can we exterminate them, please? They are one species that needs to be wiped out. 

This is coming from a vegetarian animal rights advocate. They are that bad.