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Discussion Starter · #1 ·
Hello,

I live in Michigan and did my first OAV treatment last Thursday. Checked the bottom boards on two hives and had LOTS of dead mites. Just went out today to do another treatment and when I removed the entrance reducers I saw around 100 dead bees on the bottom of each hive. I was going to do another treatment, but now I’m worried about killing off anymore bees before going into winter. I used 1/2tsp of OA for 3 minutes on battery, 3 minutes battery with off and waited 10 minutes before taking the vaporizer out. I did not expect to see so many dead bees. Is this normal? Did I do something wrong? Should I treat again? One larger hive had a pretty big mite drop (Photo attached). Any advice greatly appreciated! Thanks!!

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Are the dead bees looking "normal"? Well developed bodies? If so, my guess would be that it's seasonal die off. What was your average daily temperature since the treatment until you checked the board? It there were warm enough days for bees to take flights, I would have expected the bees to either die outside the hive or be dragged out after dying.
 

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You mention that this is your first OAV. Have you done any other sort of mite treatment on them before the OAV. It is very late in the season to be at this stage of mite control. I would be doing repeat treatments no more than 4 days apart to take advantage of remaining suitable weather. What is the condition of honey stores; number of frames of capped honey and number of spaces between frames occupied by bees.
 

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Curious why every 4 days if there's no capped brood? Or even why multiple treatments if there is no brood?
I think we could better judge the need for speed after viewing the mite drop after the next treatment. If it is down near zero then call it done. If not do another. We dont know how long suitable weather will last so I would hate to wait a week to judge results. We also do not know if all brood has emerged, though it should have. With that kind of a mite load I really dont know how their fall brood down would have played out. We really dont have much information on what has led up to this state of affairs.
 

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Discussion Starter · #8 ·
Are the dead bees looking "normal"? Well developed bodies? If so, my guess would be that it's seasonal die off. What was your average daily temperature since the treatment until you checked the board? It there were warm enough days for bees to take flights, I would have expected the bees to either die outside the hive or be dragged out after dying.
The bees looked normal from what I could tell. It’s been between 32 - 40 degrees here during the day, colder at night. They haven’t been flying and with the mouse guard on its hard to drag them out.
 

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Discussion Starter · #9 ·
You mention that this is your first OAV. Have you done any other sort of mite treatment on them before the OAV. It is very late in the season to be at this stage of mite control. I would be doing repeat treatments no more than 4 days apart to take advantage of remaining suitable weather. What is the condition of honey stores; number of frames of capped honey and number of spaces between frames occupied by bees.
The bigger hive survived the winter, swarmed in June and re-queened themselves. I did a Formic Pro treatment in August. They have 3 brood boxes and a full super of honey for the winter. It’s a 8 frame, medium hive.
 

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100 dead bees in 5 days are not many. Several years ago, every morning during the last week of December, I counted dead bees fallen on the plastic boards inserted from the bottom entrances of my two hives. Three to thirty bees fell per day (average ~10/day) and the colonies over-wintered fine (although my winter is far milder than yours).

I believe you used OA from a bee company or a trusted brand such as Savogran?
 

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Discussion Starter · #14 ·
I thought I had a mite bomb, You win!

I do hope the virus issue that accomanpies infestations as bad as this does not smack down this colony.
Not a title I was reallly going for, but I‘m hoping killing the buggers off will do the trick. It’s been a really strong hive. Only my 2nd year beekeeping. I did treat for mites earlier, but clearly not enough. :(
 

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I generally want to see less than 50 or so mites drop per colony this time of the season. When I see something like OP, I can usually expect that colony to be weaker in the spring, maybe a lot weaker, but they won't die if properly provisioned.
 

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Not a title I was reallly going for, but I‘m hoping killing the buggers off will do the trick. It’s been a really strong hive. Only my 2nd year beekeeping. I did treat for mites earlier, but clearly not enough. :(
It is easy to get taken by surprise when indrift from surrounding colonies jumps the mite load After you have treated. The extended warm weather this year would have contributed to that effect. I had to do continuing OAV through September and good part of October before the mite fall quit bouncing back. I never had anything remotely like the sticky board you pictured. My highest drop would have been not much more than 50. Common belief is that it takes two rounds of brood raised AFTER the mite load has been zeroed out for the virus titer to drop sufficiently to ensure you have a healthy batch of the so called "winter bees" going into winter. If that is correct you essentially have to have the mite load eliminated by the end of August and ensure that remains so up until all bee flying is finished.

In the north we have a much longer winter than south of the MD line so I think we need a lower threshold number of mites. Canadian recommendations used to recommend less than 3% but now 1% or less is a recommended target. This really has not sunk in and average winter mortality surveys reflect that.
 

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It seems like knowing what the real mite load was going into this fall would be important to know? Or am I missing something?
 

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The horse is long gone, Thats next years lesson. The here and now is to make sure you kill as many mites as possible so another treatment should tell the tale if those bees are broodless. If you have killed the majority of mites you could have a chance that the colony will survive the winter just make sure that they have enough stores and are kept out of the winter winds perhaps even some styrofoam on top of the inner cover and just hope that all goes well.
 

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I agree with Johno and also don't be stingy with the O.A. Your not intending to use the honey for human consumption correct? I have been seeing large commercial bee keepers using 3 grams of OA per deep. Hit them hard.
 

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Your not intending to use the honey for human consumption correct?
Remember, the FDA finalized a ruling that establishes an exemption from the requirement of a tolerance for residues of oxalic acid in honey and honeycomb. I realize that there's no label (yet) stating that it's okay while honey supers are on. I'm just saying if the honey was for him for instance, that there's likely no health risk there. Now if the EPA could get their thumbs out of their orifices, we might start making some (legal) progress.

I have been seeing large commercial bee keepers using 3 grams of OA per deep.
And higher. Dr. Cameron Jack was sharing a study with us where they got up to 4g per deep with no appreciable difference in bee mortality. No multi-year queen numbers (yet) but it's looking good.
 
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