Friendly freeloaders? These mites look like they are consuming a beleaguered beetle, but they may just be “phoretic,” i.e. along for the ride.
Well, it’s the most wonderful, unlucky day of the year! So I thought I’d find an unfortunate in the archives and share its misery with the world. Except…is it miserable? The mites are covering this beetle to awful effect as far as the uninitiated eye goes, but they might have less sinister aims than feeding on the insect. Some arthropods practice “phoresy” which is the act of attaching to another animal for the sole purpose of transportation. I don’t really know, but if I had to guess, these are phoretic mites. The beetle was not moving at all however when I found it, and the less scientific part of me had to wonder how this was not harmful or neutral for the beetle even if it was phoresy in action.
A closer look at the mites. This beetle does not have much surface area left!
BugPhoto.net 
Sure looks like he’s having a difficult time but as you say it’s a bit hard to know. Great close up of it all.
I think they are ‘along for the ride.’ I read about that somewhere. But how does the beetle fly with all that ‘mite drag?’
I can tell you, it wasn’t doing much of anything, let alone flying!
Btw, as an addendum, I have been informed that the unfortunate is a click beetle (thanks to Nikola Rahmé for the ID).