This beetle had mites like a lot of large beetles do (I think), and you can see one of them between the pronotum and the elytra in the upper half of the photo. There's also one towards the posterior, crawling on the elytra. I've always just assumed that the relationship between beetles and mites is symbiotic, but I've never heard anything about it from an actual expert. So if there's an expert out there who wouldn't mind explaining it to me, that would be awesome.