I first heard about Oxalic Acid about 5 years ago from a Canadian
researcher/beekeeper.  Well respected.  He said it should be applied only
during a broodless period because (1) unlike Formic, it would not kill mites
inside a sealed cell and (2) the *same adults* should not be treated twice
with Oxalic because for some part of the population it would interfere with
their digestive process and kill adults.

The recent work by Marion Ellis seems to contradict the latter, but he did
not say 'all adults', but only 'some'.  This guy, again about 5 years ago,
was recommending the use of Formic to 'knock down' Varroa populations in
August (if necessary, after testing with sticky boards) and then using
Oxalic as a polish killer in early winter.  He said it would generally let
him avoid any spring treatment (after testing with sticky boards).

This is in an area of Quebec 100 miles north of the US border, so much
different conditions from those in most of the US.

Lloyd

-- 
Lloyd Spear
Owner Ross Rounds, Inc.
Manufacture of equipment for round comb honey sections,
Sundance Pollen Traps, and producer of Sundance custom labels.
Contact your dealer or www.RossRounds.com

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