yeah it's a major bummer that CPs don't wipe out mosquitoes. I actually took a class in gardening CPs with my wife to get here involved a little, and someone asked that very question. The host said absolutely they catch mosquitoes. I guess she was kind of right, but sort of misleading. I just let it go.
I actually totally stopped using trays last summer because of the mosquitoes and switched mostly to bog barrels now but it actually decided to rain last week in Atlanta so they filled up so that is where they went nuts in. Unfortunately as was pointed out, neps can still grow mosquitoes (which also is a bummer...).