Hi Stephen,
RE: Osmia parasitic mites
 
I believe tht mites infesting the Orchard bees are primarily scavengers on
the pollen balls in the nesting blocks.  I've read of the chlorine bleach
treatment but it sounds very labor-intensive, hence, my research efforts.
I'll keep you posted regarding results/observations.
 
So far, I've been experimenting with Kelthane, Dikar and Pentac.  The Dikar
and Pentac are WP formulations that are lightly dusted into the nest blocks.
(Note these are NOT legal applications and WSU cannot recommend this use)
The Kelthane is an EC formulation that is sprayed into the block.  In addition,
 these materials were applied to squares of wood and mites were introduced.
 
The Pentac appears to be the only tested material that is even moderately
toxic to the mite (all three of these materials are listed in the "Pacific
Northwest Insect Control Handbook" as being non-toxic to honeybees).
 
Osmia are now beginning nesting activity and none of the materials seem to
have repellant properties as the bees readily enter the blocks and even
spend the night in the treated holes.  No toxic effects have been observed
in the adult bees.
 
Obsevations will continue.  The bottom line will be: 1- Is there larval
toxicity?  and  2- Will the mite count be reduced at Spring emergence?
 
Any input would be appreciated.
 
I'll keep in touch.....
 
Cheers!
 
Dave Pehling
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