There's a principle that if you are pained from sitting in the sukkah you are exempt from eating in it. The typical applicaiton of this ruling is when it rains.
In my back yard we have a lot of mosquitos. In warm weather you can get around 5 nasty bites in just sitting there for 5 minutes. Is this enough of a reason to exempt you from eating in the sukkah?
Would this sukkah be posul (invalid) altogether because it was built in a place with a lot of mosquitos?