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I treated 4 hives in the yard today to knock down varroa mites, vapor method. 2 of the 4 hives are bearding heavily. Normally these hives have only a few bees out front. I followed the same process on all 4 hives. Does OA tend to cause bearding like the pic attached?
Note the heavy beard on the shaded sides.
Also note the hive in the back which does not have a beard.

I tried to add the pic as an attachment but it must be too large. Let me know if you have trouble viewing the photo below.
https://photos.app.goo.gl/3sMW9x9F39bvC5Xb6

I am going to take a stab at this having been given a little more information about the hives. I have not seen a bearding response to OA vaporization in warmer or cooler weather. These hives did not have inserts on with the screened bottom boards until getting ready to apply OA. They did not have upper ventilation largely blocked. Add these changes to near 90 degree temperatures, high humidity, and a couple of strong hives, these colonies are sending bees out to beard based on normal internal temperature control given the change to air flow in the hives.

Hi --

I've treated with OA a couple times this year and I've never had any bearding issues.

When I've put menthol in the hives for tracheal mites then I've had heavy bearding. See photo