First you have to determine what type of mite it is. It is probably the Varroa mite and if it is, there are some non-chemcial and chemical ways of treating them.

[A link to a page showing what a Varroa mite looks like - http://www.ento.psu.edu/ImageGallery/varroa-1.htm]

Because Varroa mites are said to be "clumsy", they easily fall off when disturbed. You can try to use remedies that are used on honey bees such as a "sugar shake", which is a way of dusting the bee with *confectionary* sugar (baker's grade) (not powdered sugar) in a shaker where the mites will fall off. Also what is used for honey bees are miticides such as ApiLife - VAR, Apistan Strips, Coumpahos Strips, but you must check with your state agriculture department to see if these treatments are legal in your state.

Your best bet is to call your state's Agriculture-Entomolgy department or a university Entomology dept. to seek help because the remedies and doses that are used for getting rid of mites for a honey bee hive may be different for a Mason hive which differs in size, structure, population, etc. But the "sugar shake" is at least a non-chemical, more natural approach which can be done first before attempting the chemical procedures (but please check first with a bee specialist before even doing this procedure to make sure it is done properly for Masons).

But again, identifying the mite first is most important. Please see the link below for more details of what I have mentioned re: miticides, etc.

Wishing you the best in your mite treatment.

Here is a link that might be useful: VARROA MITES

Not varroa mites. They attack honey bees, not mason bees. And they're brown and rather large whereas the mites which attack masons are very small. Both the bees and the mites are native species.

The mites attacking masons are of the genus Chaetodactylus. You'll find information about them with a search on google.com.

Some folks suggest washing the pupal cases (let stand for 5 minutes) in a weak bleach solution made up with 1 tablespoon of 5% hypochlorite in a gallon of water. This would be done in September or so. You'd need to carefully open a tube of cells (use a single edge razor blade) to check the stage of your bees, then "wash" at the appropriate time.

Several sites which have been useful to me are these:
1. Bug of the Month at http://crawford.tardigrade.net/bugs/BugofMonth35.html
This discussses the mites as of 2000, then has an added note in 2005.
2. Orchard Mason Bees (WSU Extension King County Hort Fact Sheet #83)
http://www.metrokc.gov/dchs/csd/wsu-ce/agriculture/PDFs/MasonBee.pdf
This has general care, and describes the stages (month by mopnth) for mason bees.

Hope this helps.

Here is a link that might be useful: Orchard Mason Bees (from WSU Extension)