More info from Brian Spencer at Applied Bio-nomics:
I don't seem to know how to reply, or post.
Stratiolaelaps up until about 5 years ago was called Hypoaspis miles.
There are numerous mites in this large genera, but they are largely characterized as living in "litter".
They have been used for many years in poultry houses, controlling poultry mites and lice.
They cue on motion of small arthropods, and based on George's videos and experiments, they pose no risk to bees.
They bite the Varroa mite on the leg, fatally injuring it.
I personally believe that Ss colonizes the area of ground under the hives, during winter.
George is also investigating their effect on the small hive beetle.
Based on our horticultural experience, Ss should have some effect on any Arthropod that has a soil stage. For the Ss, a hive should provide the Ss with enough protection to convince it to stay in the hive, as long as there is food present.