Re: ATTN: New beekeepers with screened bottom boards
About the third time I heard screened bottom boards described, I thought to myself, "Why not put a tray of oil (or soapy water) under that to kill anything the bees push out through the screen?" I later read of the Freeman Beetle Trap. I've only heard good things about it, and I use several. Seems to have all of the screened bottom board pluses and it seals up well at will to limit most other bad effects mentioned. The tray can be as opaque as you want, to keep the hive dark (black spray paint).
I see someone else has pointed to this example, also. Good. I still think that trap design is sound. I like the polyethylene (I think) trays used because they can seal pretty well against the base of the hive and address some of the over-ventilation issues others complain about.
"I thought I made a mistake once, but I was wrong." (heard often from the late David Sebree) Still making them, myself