I used plexi on mine, and in a situation like that I drilled a few holes and would either vacuum them out or skewer them with a wire.
It didn't help all that much, but I did have great fun doing it.
In my hive they weren't such a problem in the summer or fall. It was early spring when the bees started raising brood but were really stretched thin population-wise. Then the little &*(*#$'s would lay eggs all over and get under the brood. Every year, the same thing.