Randy said, " We've withheld treatment from the zero and 1 hives to see whether
they can maintain those low numbers."

While mites are some problem in and of themselves I think what really kills hives is the associated viruses.  I have my doubts if we will ever get bees so good genetically they will eliminate varroa.  The best we can realistically hope for is bees that limit varroa to some level.  This seems the usual outcome across many species for parasites.  So, really we have two breeding targets.  One is bees that limit varroa and one is bees that can tolerate the common viruses, particularly DWV.  Doing this while also maintaining a commercial level of productivity is a pretty tall order.

Last year I did a mid March application of apivar.  My Sept mite counts were mainly zeros and ones.  I had intended to do a fall treatment of Oxalic vapor.  In view of the counts I skipped the fall treatment.  I lost 5% of my hives over winter.  This spring same treatment.  I have not done a fall count yet and did no summer counts.  I am not seeing any obvious virus issues.  Few crawlers and I have only seen one bee all summer with K wings.  No shriveled wings and no small abdomens.  If I see counts mainly like last fall I will not treat again this fall.  I am running Minnesota Hygienics which I have bred long enough the local drone population should be mainly MH genes by now.  I would estimate they are more or less 70% MH genetics.  I doubt if these bees are productive enough to be used commercially if pure.  But, they seem a great pick for people who are back yard bee keepers or somewhat out of control back yard bee keepers like me.

My feeling is if I saw a hive with a high mite count in the fall, but as a whole the mite counts were low I would be inclined to just let the high count hive go untreated and if it died say good to get rid of it.  I over winter way more than enough nucs that a dead production hive is no big deal at all.  My nucs are generally five over five deeps by fall and many as much as three boxes tall and two or three four boxes tall.  So, they really are not nucs.  They are instant full sized hives come spring.

I really think that early spring apivar is important.  It knocks any over wintered mite population to such a low level the bees seem to cope pretty well.  It is not anything to do with local conditions.  Before I treated and started the MH queens I had very high mite counts, obvious rampant virus symptoms and high over winter hive deaths up to 50%.

Dick

" Any discovery made by the human mind can be explained in its essentials to the curious learner."  Professor Benjamin Schumacher talking about teaching quantum mechanics to non scientists.   "For every complex problem there is a solution which is simple, neat and wrong."  H. L. Mencken

             ***********************************************
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