Re: What do dead mites look like on a bottom board/tray?
Keep in mind that a good hive will clean debris off of a bottom board pretty quickly especially with a smooth material such as you are using.
An easy solution for a poor mans sticky board that I have used is to smear some vegetable shortening on some cardboard or the like cut to lay on the bottom board. Check it a day later to get a pretty good idea of your mite drop. You shouldn't go much over a day, though, as the bees will clean it off fairly quickly.
"Ve are too soon olt und too late schmart."- A nameless German philosopher