>Is it definitely known now how OA drizzle kills varroa?

Varroa is far more susceptible to acids than is the honey bee.

There appear to be two modes of exposure to the mites.  The first would be
through direct contact, which Aliano demonstrated would kill them.

The second would be since from bees grooming the OA syrup off their bodies
and ingesting it.  It spikes in their haemolymph for a day, then drops
(Martin-Hernandez).  I suspect that mites are exposed when they feed on the
haemolymph of those bees.

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

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