Here are our preliminary results:

In ten yards we obtained 45 mites from two to four hives by sugar shakes, using
about a cup of bees per hive with all the sugar dumped into a single bag per
yard for later analysis by dissolving the sugar in water.

We then immediately placed two Apistan(r) strips into each of the same tested
hives and inserted sticky boards with screens.  The strips and boards were left
in the hives a minimum of 24 hours and a maximum of about a week (see data).

The sugar gave us 49 mites and the boards returned 2384 mites for a ratio of
about 49 mites dropped by Apistan for each mite found by sugar in the same
hives, however one must consider that some individual hives and some yards
returned zeros for both tests and therefore a simple ratio like 50:1 cannot be
used.  A quick glance reveals that the ratio varies from around 15:1 to
infinity:1.  Several hive groups that gave zero results from sugar shake
subsequently yielded mites in the hundreds.

Here is the raw data:

Board
P/u   Yard Name         Sugar   Result  Sticky  Result
Date                            Shake           (Mites) Board           (Mites)

O5      BCNE                    S28             0               S28             0
O5      BCSW                    S29             0               S29             0
O5      BCSE                    S29             0               S28             13
O5      Jahns'          O5              3               O5              0
O5      Taylors'                O5              0               O5              1
O13     Vanovers'               O10             0               O10             28
O13     KadarE          O6              0               O6              235
O13     KadarW          O6              3               O6              235
O13     ButlerW         O10             0               O10             162
O13     ButlerE         O10             0               O10             41
O13     Pisco                   O11             0               O11             204
O13     Hainsworth              O11             0               O11             63
O13     Dixon Bush              O11             28              O11             421
O10     Wilson                  O10             4               O10             288
O11     Dixon           O11             8               O10             22
O12     Beckwith's              O12             5               O12             72
O12     Schlags Hill    O10             0               O12             213
O10     Schlag CS               O10             0               O10             2
O13     Rattai          O12             1               O12             381

Key: O13 is October 13, S29 is September 29

The work was done by our competent commercial beekeeping staff while going about
their normal activities, following standard procedures. Our location is east and
north of 51.1 N, 114.02 W or around halfway between Lethbridge and Edmonton,
Alberta CANADA.

I would be interested in comments from scientists and extension people as well
as beekeepers on what to make of this.

allen
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A Beekeeper's Diary: http://www.internode.net/HoneyBee/Diary/