Jervis, lab where i work is food testing lab and we do a lot of analysis for FDA submission and one of department is called food forensic, they look for all sort of unnatural stuff in food (mostly rice and spices). For that reason we have our own entomologist and yes I am very happy and lucky we have him!

So i was Googling those soil mites and there is not that much info on them!!!

On other orchid forum someone posted similar question and one of answer was that they dont do harm to orchid (but its not researched) but do eat algae that grows on roots and are not considered pests. There also was a link to american orchid society's website where they discuss spider mites and mention little bit this ones. Here is the link to that page Mites I