Hello Tim and All,

Tim wrote:

I don't recall the original message indicating the method of selecting
the 5 random individuals from a given colony.  Were they randomly
selected from the entire cluster (ie. some from the edge, middle, etc.)
or were they simply the first 5 bees to the entrance when you knock
on the hive?  It makes a difference.


Allen does not use hard tops in winter so the samples were taken from the top of the cluster by pulling back the pillow..

Under summer conditions Tim would be correct but at the time Allen took the samples  most if not all of  the bees were older bees and very little brood rearing is going on. The bees are in Cluster most of the time and varroa is existing on feeding on the older bees  In my opinion the sample bees would be a fair indicator of the entire cluster.
. 
Nosema and tracheal mites typically pass through the whole hive in the winter cluster in heavy nosema  and heavy tracheal mite situations..

Although many bees carry only a traceable amount of nosema while others carry the full infection Nosema can be detected in most bees from a heavily infected hives with a microscope.

When a hive becomes heavily infested with tracheal mites  most bees will show a few mites if you look close enough. 

When I dissect a bee trachea and it is black from mite damage I need to look no further. 

A white trachea does not necessarily mean zero mites either only that the infestation is not severe or in its early stages. These are the tracheas which take time to examine.

Sincerely,
Bob Harrison

Ps. I am only a beekeeper and not a researcher but the above methods work for me and reflect my experience dealing with mites and nosema.