I've had the Beetle Baffle on for several months, and finally pulled all of the boxed off to look at the bottom board.
I still had beetles in the upper boxes. I can't say for certain that there were fewer beetles. 3Reds seems to think so.
When I looked on the bottom board, I saw a few beetles, as well as some bees chasing them around. There were probably more beetles tucked away in the crevices.
Looking at the two other hives with the Freeman bottom board and the trays filled with soapy water, I found a few beetles, but I also found a lot of larvae floating around. One wax moth larvae, and several SHB larvae. I could also see quite a few mites that had fallen in. I didn't count things because there was a ton of trash in there too.
My conclusion is that I'd rather stick with my Freeman bottom boards. The beetles, larvae and mites that fall into the soapy water die. I don't know what happens to the beetles, larvae and mites that fall onto the wooden bottom board.
I use soapy water rather than oil because the oil begins to smell rancid after a while if you don't replace it, and it gets expensive. We don't fry foods enough to keep a big supply on hand, so I was using fresh, cheap vegetable oil. When I switched to soapy water, I realized I need to check the trays every three days or so. Otherwise the water evaporates.
Freeman suggests pouring water into the tray and then adding enough oil to cover the surface, which would be cheaper than filling the whole tray. But I still prefer soapy water.
