Varroa 4
Monitoring for Varroa in March
In the last week in March a varroa screen was placed under each OMF for 9 days (hives: A, B, C, D, E, & F). The natural mite drop was found to be respectively:
A 0, B 0, C 0, D 0, E 25, & F 1.
varroa screen
A typical varroa screen in early spring after 9 days under the OMF. The large 'drops' are pollen. Only 1 mite was found on this screen.
mite count2
What conclusions can be drawn from this experiment?

Firstly, it was pleasing to find that after measuring the natural mite drop over the initial 9 days only one colony (E) gave any cause for concern: when 25 mites were counted.

Secondly, during the treatment the mite drop was monitored daily. There was an increase in the mite drop in each colony except B where no mites was seen.

Thirdly, the treatment was deemed to be successful because no mites were seen to drop from any of the colonies in the final two days of the treatment.

See next page for the results of the August experiment.
Each colony was then treated with formic acid for a period of 9 days, i.e. 3 doses of 20 ml 60% acid at 3 day intervals. As described in Varroa 3 in the menu above).
The total mite drop in each colony was:
A 5, B 0, C 7, D 2, E 30, F 3 in this time. No mites dropped on the final two days of treatment in any of the colonies.
mite count1
During the treatment no difference in the behaviour of the bees was noticed. The bees continued to forage normally.
In colony E where most mites were seen the daily mite drop over this 9 day period was :
9,15, 2, 4, 0, 0, 0, 0, 0.
mite drop3
Next Page: Varroa 5
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