Friday, November 18, 2016


After reading the varroa mite articles in the Nature's Nectar blog and seeing sticky board pictures sent in by beekeepers Gerard and Grandpa Jack I decided to do another mite check on one of my hives.  I chose to utilize a sticky board so I could directly compare with the pictures from those three sources.  
So Wednesday I slipped a sticky board into Hive U.  This hive has a Ankle Biter queen.  I had previously treated the hive with MAQS in mid-August and again in mid-September and mid-October with oxalic vapor.  I was not expecting to see many mites.  When I removed the sticky board 24 hours after another oxalic vapor treatment I counted 19 mites.  
                                                                   Mites are circled.

So now for a big question.  Are 19 mites good or bad?  I had absolutely no idea. Gerard indicated this was much lower than what he had seen from his hive.  Like most beekeepers I was not able to find a handy go/no go recommendation for the method I used.  The closest I found were limits ranging from 12 to 50 mites for a "natural" mite fall onto a sticky board in 24 hours.  "Natural" mite fall occurs from mites dying and dropping or being groomed and dropping or just losing their grasp on a bee and dropping.  I could not find a limit for my accelerated method which used oxalic vapor.  

In a beehive at this time of year the population is slowly declining.  Right now I am guessing the population is in the 20,000 to 30,000 range.  I've seen recommendations that mite infestation levels should be in the 1 to 5% max level.  A 1% level means there are about 300 mites on 30,000 bees.  Oxalic acid vapor is reputed to kill 95% of the mites on bees (not those on capped brood).  95% of 300 is 285.  So potentially on a "good" 1% hive I could kill 285 mites.  From this I am making the inference that my 19 mite fall in 24 hours is "GOOD".  Since I have treated all my hives in a similar manner I am feeling good about my chances for good winter survival.  It looks like the snow may start flying next week so my outdoor beekeeping is done until spring other than periodic checks tosee if the hives are still humming.  Stay tuned.   

PS-you probably saw that I treated my hives with 2 different natural acid compounds; MAQS (formic acid) and oxalic acid.  MAQS is reported to be able to penetrate the brood cell and kill juvenile mites. MAQS is also reputed to have a higher potential for killing the queen; therefore I was hesitant to apply it more than one time.  MAQS also needs warmer temperatures to be effective.  Oxalic acid can be used at lower temperatures; down to 40F.  However, oxalic acid does not penetrate into the brood cells. It is most effective after the queen has stopped laying and all capped brood has emerged.  I had also just received the oxalic vapor tool and was playing with it.     

1 comment:

Gerard Schubert said...

Good article, and I believe Hive U is in excellent shape, mite-wise, for winter.

I still need to put on sugar and winter covers, but not in this hurricane. Tomorrow looks more promising.