> I'm trying this test today, but surely the laws of chance are at play here?
> If you put strips in, or smoke or fume, thousands of bees are affected. If
> you pick up the wrong jarful of bees there may be a wrong conclusion?

We've covered a lot of these matters in quite a few posts over the last year or
two, but I think it might be helpful to re-cap here:

The ether roll and the sugar shake are quick-and-dirty tests that can give a
ballpark idea of the level of a known infestation, and an idea if treatment
should be imminent.

They can be effective where varroa is known to exist in fairly high numbers, but
are not nearly as sensitive as using a sticky board with Apistan for 24 hours or
formic for 48.

Where mites are not known to exist at all, and only a few hives are being
checked, the ether roll and the sugar roll are relatively insensitive, since
only 100 adult bees are sampled from a  hive.  I am uncertain how either
compares with the alcohol wash (which uses 300 bees/hive).

Of course larger samples can be done with sugar, and in our operation, we use
about 1/4 of the quart mason jar full rather than 100 bees.  As an idea of how
insensitive it can be, we have tested 15 yards with four samples per yard and
only found two mites.  Both were from one yard.

We have not treated this year.  I'm sure if we had done the same hives with
either mite drop test, we would have found much more than 2 mites.  However, we
would never have done the tests on so many hives because they involve two trips
and applying acaricides. We still have supers on.  We're just quickly looking
for any sign of heavy infestation in case emergency measures are indicated.

Any such test, including the mite drops, only measures mites that are on adult
bees,  Consideration must be made for the season and the amount of brood present
to get a true idea the actual mite load in a colony. In fall and winter, the
tests are much more sensitive, since a much larger percentage of the mites
present in the hive are on the adults compared to brood.

Also, check out http://www.rossrounds.com/HoneyBee/Formic/

allen
---
A Beekeeper's Diary: http://www.internode.net/HoneyBee/Diary/
Package bees, winter loss, fondant, Pierco vs. Permadent vs. dark comb,
unwrapping, splitting, raising queens, AFB, varroa, protein patties, moving
bees, pollination experiences, daily mumblings and more... Thousands served...