My worm bins are producing tons of little black beetles. They're about .5cm long and can fly. I didn't have any until I set up the most recent bin. They're only in this new bin. I added scraps to this new bin but forgot to add worms until about a week later. Did the beetles take over this bin because the worms weren't there to compete with them? I know the beetles are beneficial, but they get through my window screens and are a nuisance. How can I reduce their numbers? Thanks.