I tried an experiment recently involving sugar dusting on solid bottom boards. I have 8 frame hives, with a bee space between the bottom board and the hive body just under 1/2". I purchased elmer's poster foam board (for the science fair displays) to use as sticky boards. Unfortunately, these just barely fit in the bee space. Other materials I researched were far too expensive. Corrugated plastic was another option but my local sign company would've had to special order them with a 2 week wait time.
Anyway, I performed sugar dusting on about 10 hives using the method Randy Oliver describes in his recent articles in ABJ. (except for the screened bottom boards obviously). I sprayed the sticky boards with cooking oil. About 10 minutes after dusting, I removed the sticky boards from the hive to count the mites, then replaced it for 24 hours. When I counted the mites the first time, every board had over 40 mites when I stopped counting. 24 hours later when I removed the boards, they had 3 to 5 mites.
My question is: What happened to the dozens of mites present on the board the day before? Did they hitch rides back on bees due to my lack of a screen? That is my theory. It seems that a screened bottom with a space between the sticky board and the bees is essential.
I have read other threads on this board describing dusting without a screened bottom and having great success, so I'm wondering if I am not doing something right.
Has anyone else had this same experience?