Mites parasites on body, I suppose, otherwise I don't know where they came in the box where I have collected it for photos. (I didn't see the mites when I collected it.) I'm not exactly sure how they came in the box. With the grasshopper I have collected and two small debris of uncertain origin. Probably plant debris and I think it is very small probability to came from this debris. I think it's the first time I see such a mites associated with a grasshopper.

In night, attracted to light. But, curiously, the mites have spread in the box. Often they remain attached to the host.
The grasshopper had movements, flights and jumps, disordered hitting the wall. I saw frequently this in case of insects infected with mites parasites. Not necessarily but frequently the insects are very agitated in such situations.