# Varroa Mite shake down



## Bee Arthur (Mar 21, 2015)

Michael,

For a few years I've been working on a way to determine mite load based on post-OAV mite fall. Because all of my data is taken from 24-hour mite falls, I can't speak definitively about your 48-hour drop. But you may get some ballpark ideas about the health of your hive by playing around with my online calculator. Next time, if you check your mite drop the next day, the calculator should be more insightful.


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## beemandan (Dec 5, 2005)

Did you count how many fell out during the first five days after treating? Mine have been dropping 300 to 600 total during the first week and running 15 to 30 a day for the next few days. 
Oav doesn't kill them immediately. They tend to really hit a peak at about day 2 to 5 and drops seem to remain elevated for another few days. .


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## Kuro (Jun 18, 2015)

I think your bees still had capped brood at the time of treatment and those 60-75 mites emerged recently and died natural death. I would do at least one more OAV to get rid of mites still clinging to the bees. I’m in Seattle area and 2 years ago I did a single OAV on 12/19/15, assuming that my bees were broodless. However, mites kept falling even after 2 weeks so I did every 5 day OAV in January to get rid of remaining mites (see below for the actual counts I got). This year, I kept observing hive trash and the last day I found dead pupae was 12/17/17. I will do the first OAV on 12/24, count mites at 48hr (I’m sure >100 will fall), then do 2 nd OAV on 12/31 and count mites at 48hr. If the 2 nd count is low, I will stop there. Otherwise I will do 3 rd on 1/7.

>Is the kill process of mites immediate with vaporizing?
I think mites can get killed pretty quickly if exposed to sufficient concentrations of OA. In this study scientists put mites in glass vials coated with various concentrations of OA and determined mortality after 24 hrs (http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1049&context=entomologyfacpub). In reality, however, the hive interior will not be uniformly coated after OAV and a mite may or may not step on it immediately.

>How long does it take for the bees to shake down all of the dead mites out of the hive and down through the screened bottom board? 
Within a day? I’m just guessing here.

>When is the best time to do 48 hour sticky boards after vaporizing to determine what the live mite levels might be?
I have never seen wiggling mites but then I do not use sticky boards (just plain plastic boards) so I only count dead mites to gauge treatment effect. Like many other people, I insert boards immediately after OAV and count after 48hrs. It should give me 5-50 times more dead mites compared with pre-treatment counts. Then I repeat OAV + 48hr counting until I get <10. I also look at 48 hr natural drop 2-3 weeks after the treatment, which should be near-zero. 

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(Mite drop in two hives after single OAV performed on 12/19/15)
12/19-22 = 81, 94
12/23-24 = 46, 69
12/25-31 = 52, 92
1/1-1/3 = 20, 15

(The round OAV result)
2 hives vaporized on 1/3/16, 1/8, 1/13, 1/18, 1/23
Mite drop during the first 3 days after each OAV
Hive 1: 84, 130, 108, 32, 8
Hive 2: 94, 88, 52, 18, 9

(Mite drop in two hives, ~10 days after the round OAV)
2/3-2/5 = 0, 1


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