After all these years I have finally found mites in my drop pan. Two of the overwintered hives have them. In hive No. 3 I found one, and in hive No. 2 I found four. Both of these hives were the ones I had made such a critical error in not using top bars in every box. Here's hoping that the bees can take care of them as they did the beetles. I have also been finding a lot of moths in the drop pan. This seems to be an added bonus, because I think they are trying in vane to sneak in the back but can't get in and then get covered with D. earth and die. Have also found a couple moth larvae too, also dead.