I have a hive that I put quite a few foundationless frames in and they promptly created drone frames. I had a lot of drones wandering around later and saw mites on these drones. Not only that, I saw a few bees with dw. I never did a mite count but I'm sure it was rather high. It concerned me, but being the lazy and uneducated keep that I am, did nothing about it. Now, six months later, this hive made it through fine, apparently, and right now is very big and strong. After reading other posts on mite control, I guess that I am just lucky. But I'm hoping that these bees have found a way to control the situation themselves. Time will tell.