Blane writes:
>I too am a little uncomfortable with the sampling method for varroa but winter survival data indicates no varroa problem.


Unless we have something to compare it with, samples in the middle of winter mean next to nothing. I assume he did this in March, though he doesn't say. In my experience, this is too early to assess winter losses. Many hives fail during the spring build-up period, presumably because the bees are all too old at this point and they just die off too fast before new bees are available. Perhaps they are incapable of raising very much brood if they are too old.

Without sampling the center of the cluster *and* the edge, we will never know if sampling the edge is effective in detecting *any* levels of varroa. Remember, his numbers were consistently zero. But that proves only that there weren't varroa at the edge, which I wouldn't expect there would be. I would expect them in the warm center of the cluster.

These are some of the reasons why I would not approach the problem the way he did, even if the 175 bee per apiary is statistically large enough (I would still opt for a sample size around 250 -- how else can you detect levels as low as 1%? If he is just looking for dead-outs and colonies with varroa levels of 30 -40%, he may find them this way. I would still rather sample 3 or 4 hives (10% of 35) correctly and extrapolate the data from this.

Doing a correct sampling of 10% of the hives will give a pretty good idea of the infestation rate of the apiary, in my opinion. It involves opening fewer hives, too, although it involves killing more bees (750 to 1000). Again, unless we are going to compare this to data we have collected previously, or data someone else has compiled -- in itself, it won't mean much unless the levels are high. Then you better be thinking about what your treatment options are.

pb