Some weeks back, we discussed the interesting fact that varroa are not 
evenly distributed in drone brood and that often a patch can be found with 
multiple mites per pupa and other patches in the same hive with little or no 
varroa on the drone pupae of similar age.

Here is another observation.  Apparently the varroa are not evenly 
distributed in the cluster.  In fact they are very unevenly distributed --  
if my observation yesterday is any indication.

I do a lot of varroa sampling for other beekeepers, and have been instructed 
when sampling 300 bees for varroa, to look for brood in the top brood 
chamber box and to sample bees from a frame containing brood.  The age and 
the amount of brood does not matter, but there must be brood on the frame. 
If there is no brood in the top box, I am instructed to close the hive and 
move on the the next rather than go to the labour of disassembling the hive. 
In some occasional yards, that means many of the hives are not suitable to 
sample under these instructions, but this has been what I was doing.

At any rate, yesterday I was out with an old friend, checking his bees.  We 
went through three yards, and near the end of the last yard, where we had 
been getting some fairly high numbers we found a hive which had recently had 
brood up top and had some empty cells waiting for the queen to lay.  We knew 
she would not since they are shutting down for the year, but we took a 
sample, assuming that that this would not differ from a frame with actual 
brood.  It was almost the last hive at the end of a long day.

We sampled 300 bees from this frame, shook the sample, and got two mites. 
We then thought better of cutting corners and and went into the bottom brood 
box, where we found a frame of brood.  We sampled bees from that comb, shook 
them and got seventeen varroa!

I have always known that there is a difference in mite loads between older 
bees and the nurse and/or winter bees, but would never have imagined it to 
be so huge.  I had thought that the difference might be a factor of two, not 
eight!

We imagine that bees mix and wander throughout the hive, but it seems they 
do not under many normal conditions.  We know that the young bees hang 
around pretty close to the brood most of the time since they are the ones 
which eat the pollen patties, and that pollen patties need to be within two 
inches of brood to be eaten reliably.  If the patties are placed elsewhere, 
they are pretty much ignored, except in a strong flow in summer when this 
rule seems less important and perhaps the young bees wander more.

If my experience yesterday is not a freak, and I doubt that it is, this 
observation also shows how very important it is to get mite treatment into 
contact with the bees which have the heavy mite load.

Simply placing the strips into hives is very unlikely likely to have maximum 
effect.   This may also explain why formic treatments are variable in 
efficacy. 

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

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm