My understanding, from a Canadian researcher, is that if the *same bees* are 
treated twice with OA they tend to develop difficulties with digestion of 
foods. At a presentation I attended, he recommended treating with formic in 
late fall to kill the bulk of the mites and then 'polishing' with OA (by 
drip) in early winter. He maintained that this combination would mostly make 
it unnecesary to treat again until the following fall.
 However, he did recommend monitoring in July/August and treating any yards 
that had 3-day mite falls over 30.
 See http://www.reineschapleau.wd1.net/articles/IPM%20with%20APINOVAR_en.pdffor
more information.

-- 
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 <http://www.RossRounds.com>

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