November final OAV treatment - unpleasant surprise

[tjc1]

After three OAV applications a week apart in early October, I noted that one hive was still showing regular drops of mites on the bottom board, so I decided to give them one more (now broodless) treatment going into winter. Over 60 hours, they dropped 517 mites. Yikes! I was surprised to see so many after the October round of treatments - I wouldn't have thought that there would be much capped brood left in October for the mites to be hiding among.

[GSF]

Could it be a bad batch of OA? ...if there is such a thing.

[Hops Brewster]

Phoretic mites that came out with the last of the brood emergence.?  And/or mites brought back from your bees' robbing raids on other colonies.

[tjc1]

Same container of OA used for all treatments.

More mites dropping:
- next 24 hr period = 317,
- last 24 hrs = 228!

These mites are all black - someone asked me earlier in the year whether the mites that I was seeing were old or young mites , and I hadn't realized there was a color difference - most at that time were brown, so I'm guessing that these are older adult mites.

One other thought - when the weather was warmer I always found ants wandering on the bottom board. I watched them to see if they picked up mites (which I've heard it said they do) but never saw them take one. But maybe they were in October - the mite drops were much smaller for those treatments (ca 150 over 4 days).   

[tjc1]

Still dropping mites! over the last three days, about 50 per day.

[Dabbler]

Could your bees be robbing a mite infested hive?

[tjc1]

Interesting thought. It has been pretty warm so the bees have still been out, even coming back with Pollen, so I suppose it could be possible. On the other hand, the hive weight has been dropping which you would expect during a warm early winter, which might indicate that they aren't bringing in much in the way of nectar - or robbed honey.

[davers]

Does it matter if you do the OAV treatment in the morning when the bees are clustered or in the afternoon when it warms and the bees are flying?

[tjc1]

Ideally you try to treat all of the bees when they are inside the hive, as OAV can only kill mites that are on adult bees - it does not kill mites that are inside cells with capped brood.

[Michael Bush]

>These mites are all black

Mites are cordovan.  Or, if you will, purplish brown.  They are not black.  The immature ones are white.

[tjc1]

Hi Michael,

Well, the summer mites were dark brown to tan in color, but these are all very, very dark verging on black - but I guess they could be that purplish brown in strong light.

[10framer]

are you looking at mites or hive beetles?

[tjc1]

Yeah, mites for sure. I only rarely see a hive beetle, but I know what they look like, too!