Agree that it's contact, Bill, but have no idea as where on the mite is
critical.  We need to do more experiments like the one that Paul did, but
with precise placement of the OA.  The question is to what degree it
penetrates the mite's hard cuticle, or whether it needs to contact soft
integument or other tissue (or whether it simply interferes with the mites
olfactory sensors, preventing it from being able to feed--and thus perhaps
dying from simple dessication).

I realized while in the bee yards today that I was in error in my previous
calculation.  Based upon at least one reliable data set, as well as my
modeling, in late summer, roughly 50% of the mites are typically phoretic
at any time.  That indicates that they are phoretic for about 12 days per
reproductive cycle (rather than for the 5 days that I previously stated).

That means that an oxalic vaporization repeated at 7 days would
theoretically be more effective than my previous calculation.  However, the
feedback that I've received from a number of beekeepers who have used
vaporization suggests that they get better results when reapplied at a
shorter interval.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html