Hello Richard and All,
> As I understand it, when Imidacloprid is used to control Varroa, we put a
sub-lethal dose (to bees) in the hive.  If the agent is available outside
the hive, it is possible to raise the dose to a level lethal to bees.

Imidacloprid has NEVER been used to control varroa.  Did you write the wrong
word Richard?  Bayer will talk unless they are under attack about a product.
Sincerely,
Bob Harrison
Odessa, Missouri