I decided to go back and see if I could find that beetle again and get more pictures, and I did!! While these beetles have potent chemical defenses in the form of caustic oil they secrete, this one was quite placid and let me get up close with the clip-on phone lenses, even crawling onto my hand at one point.
The mite mostly stayed under the beetle's chin, but occasionally ran around its head.
A passerby asked what I was looking at and I am afraid I was not the best or most observant conversationalist, as I was busy taking all the pictures I could get, but he seemed familiar with the concept of phoretic mites at least, and remarked that perhaps the mites gained some benefit or protection from the beetle's secretions.
This BugGuide observation <https://bugguide.net/node/view/31709> seems similar?
#DailyMitePic #Mitestodon #mites #bugstodon #insects #beetles • #Acari #Parasitiformes #Mesostigmata #Coleoptera #Meloidae