I don't know if this will answer your question, but Friday I went to put sugar on the top of the frames. I didn't use any smoke and had bees all over my bee suit and gloves. While looking to make sure I got all the bees off, I found a mite crawling on my hand.
Right now, with no brood, I don't think they have a choice but to stay on adult bees. I, too, looked for mites all summer and thought that I had the only hive in America that didn't have mites. Until I slid the white board under the hive and discovered how wrong I was.