It's never good when things like that are found crawling all over the frog, especially in that one picture you posted but I do know when I do get mites I right away tear apart the tank, clean everything and set each animal in it's own quaratine until I notice them vanish. Anything crawling over them constantly will cause them stress, especially since they can't get away from them. My toads don't even like crickets moving across them and shy away from food coming right up and touching them. In wild conditions they'd be able to move from a spot and get away from the majority of them. I don't agree with the idea that it's okay to have springtails crawling all over everything.

The only mites I've had before haven't clinged to my frogs so I'm under the assumption that they might be getting something out of it, simply because things that aren't trying to be parasitic don't cling to animals without getting something out of it.

It's not heat, being cold blooded ... had to be they where feeding, or laying eggs on it. If just by sheer numbers that many where crawling around his face then you defiently need to clean and get them out of there.

My only suggestion if you don't want to clean the cage is to let the substrate dry out - This can help control any mite or bug population. I've only noticed explosions of such pests after watering down my substrate. Pacman's will actually move around more to, to their burrow site of choice and to the water bowl. Dry coco-fiber works just fine and doesn't need to be soppy wet. It's good for them to move around anyway.

Good luck!