I've been toying with this idea - A beetle trap that uses the same basic idea as a bee escape/minnow trap/trap out cone. That is - funnel the buggers into a cage that they can't figure out how to get out of.
I figure once they are confined without access to food/water they will mostly just dry up and die without much mess - no more disgusting oil full of putrid beetle/larva corpses. If it was incorporated into the bottom board it might even catch the exiting larva.
The easiest way to try this would be to just staple a piece of screen wire on the back of an escape board, and some #8 HW Cloth over the escape entrance hole - although I'm sure that some other configuration would be more efficient. Something with SHB entrances in the corners of the top and/or bottom boards (using their usual refuge areas to corral them in) maybe, or round "cartridges" that could insert into holes drilled near the hive entrance (using the hive smell as bait) maybe.
Anyway, before I reinvent the wheel - has anyone tried this before?