Moved from Mites and Ticks.

I think these are Tyrophagus (Acaridae). These mites never cease to amaze me. If you have a pet arthropod in an enclosure, and it dies, Tyrophagus can be found eating the carcass within a day! How did they get there?!? One possible answer is the deutonymph in Astigmata is known as a hypopus. Hypopi are heavily sclerotized (hard), resistant to desiccation, have no functional mouthparts, and have suckers on the venter. The suckers enable them to attach to other animals for dispersal (I've even seen hypopi on the legs of erythraeid mites!). Possibly they are phoretic on the dying arthropod, or maybe carrion associated flies? Who knows.

There's a nice bit of information on some [i]Tyrpophagus[/i} here: http://www.the-piedpiper.co.uk/th7g.htm.

Moved from ID Request.

The only mite collections I've done were environmental samplings using a shop-vac with an adapter on the nossel for trapping mites- probably over-kill for your purposes! I have had good results using a small paintbrush for transporting 1st instar ter"mites" into container. Use the side of the bristles rather than the tip, twisting the brush to roll them up off of the substrate. Transport in a well sealed container. Use a compound scope if you have one with a drop of water on the slide to help hold the specimen in place. Good luck!