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  1. #1
    Join Date
    Feb 2009
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    Algonquin, IL, USA
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    Default Something you probably didn't know about mite control

    Did you know that female mites react very sensitively to high relative humidity such that they almost never reproduce at levels above 80%? If you could keep your hive at 80% RH, it would be virtually impossible for an infestation to occur.

    I believe you can most certainly use this to your advantage when overwintering and during spring buildup. The hive is a very humid place. Why do you need an upper entrance? It's to prevent all this excess humidity from condensing over the bees and dripping down onto them. Well, why not just heavily insulate the top of the hive (more so than the sides) such that all condensation forms on the sides of the hives? That's exactly what I did this year.

    I decided to go without an upper entrance in order to maintain the hive at the highest humidity level possible. I could care less about condensation (and I have a lot of it). As long as the condensation forms on the walls of the hive, I figured I would be OK.

    My results (so far) are fantastic. Very good orientation flights out of both of my hives yesterday (temps in the 60s). I pulled the bottom boards and could not find a single mite. Believe me, I know how to find mites.

    This overwintering technique would be very similar to a hive overwintering in a tree.

    Now, I believe at this time of the year my queen should begin laying in earnest for the spring build up. I'll keep you guys informed on my results.

    Ken

  2. #2
    Join Date
    Jan 2003
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    Suffolk, VA
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    2,277

    Default Re: Something you probably didn't know about mite control

    What's the source for this information?
    Horseshoe Point Honey -- http://localvahoney.com/

  3. #3
    Join Date
    May 2011
    Location
    Richmond, VA UNITED STATES
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    160

    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by c10250 View Post
    This overwintering technique would be very similar to a hive overwintering in a tree.

    Ken
    Interesting. I have done some cutouts in trees. The bees are in there because the inside rotted out. Usually right below the colony is a lot of colony deitrus. If the outside of the tree is thinner, there should be hive condensation that will run down and rot out the tree even further. During this summer this material is drier, but I could imagine it being much wetter in winter.

  4. #4
    Join Date
    Feb 2009
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    Algonquin, IL, USA
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by AstroBee View Post
    What's the source for this information?
    Many scientific papers. Just Google "varroa high humidity"

    http://igitur-archive.library.uu.nl/...5/UUindex.html

    http://link.springer.com/article/10....050382?LI=true

  5. #5
    Join Date
    Nov 2011
    Location
    Rader, Greene County, Tennessee, USA
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    4,969

    Default Re: Something you probably didn't know about mite control

    One study that may support this idea is here:
    http://link.springer.com/article/10....Fs001140050382
    however, they want you to pay $40 to access the document.

    Before you decide to pay $40, you might want to read this:
    http://www.honeybeesuite.com/hive-hu...-reproduction/
    Graham
    USDA Zone 7A Elevation 1400 ft

  6. #6
    Join Date
    Aug 2002
    Location
    Nehawka, Nebraska USA
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    43,492

    Default Re: Something you probably didn't know about mite control

    80% would give a decided advantage to the SHB though...
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

  7. #7
    Join Date
    May 2012
    Location
    Sacramento, CA, USA
    Posts
    2,437

    Default Re: Something you probably didn't know about mite control

    How does this translate to controlling mites during their peak when it's hot and dry?

  8. #8
    Join Date
    Mar 2012
    Location
    Sacramento, California
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    119

    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by Michael Bush View Post
    80% would give a decided advantage to the SHB though...
    what's the source of this information?

  9. #9
    Join Date
    Mar 2010
    Location
    Walker, Alabama, USA
    Posts
    774

    Default Re: Something you probably didn't know about mite control

    Okay, I admit I haven't followed the links, but as a former Florida beek, this doesn't jibe with my personal experience. Humidity along Florida's west coast is normally quite high. I was inland, yet still only about 8 miles from the Gulf. I had mites. Boy, did I have mites. And SHBs. They both seemed to be worse in the summer when my pastures were still underwater (often for weeks at a time), They were also present in the winter months, which are drier but cooler and there was less brood, so the mite numbers weren't as high. But they were still there. And the SHBs were there all the time! Even then the treatment strips didn't seem to me to help very much. I lost a hive to SHBs in January my last year there.

    JMO

    Rusty
    Rusty Hills Farm -- home of AQHA A Rusty Zipper & Rusty's Bees ( LC and T)

  10. #10
    Join Date
    Mar 2011
    Location
    Slidell, LA, USA
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    259

    Default Re: Something you probably didn't know about mite control

    That sure makes it hard to explain our problems in SE Louisiana. It gets below 80% humidity a couple days a year during the winter but other then that, hot and damp.

  11. #11
    Join Date
    Nov 2012
    Location
    Columbia, Maryland. U.S.A.
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    249

    Default Re: Something you probably didn't know about mite control

    Ken,
    Very interesting, I assume Lang ? height ? insulated top only ? wrapped ? Please do keep us posted.
    Cheers,
    Drew
    "Nature does nothing uselessly." Aristotle

  12. #12
    Join Date
    May 2011
    Location
    Richmond, VA UNITED STATES
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    160

    Default Re: Something you probably didn't know about mite control

    Don't the bees need to dehydrate the honey? I wonder if you can even get a high humidity in the winter. If there is a condensation surface (cold hive body) doesn't that mean that moisture is going to be removed from the hive? So, the bees are going to move the moisture out during the summer, and in the winter, it's going to condense, it seems as if there is constant mitigation to hive humidity - anyone keep a digital hygrometer in a hive?

    Ater thinking about it, though an insulated inner cover does create a more "tree like" condition, it's possible that the warmer inner cover just reduces the consumption of honey by the bees. As for mite counts being low, there's not that much drone comb in winter...

  13. #13
    Join Date
    Jan 2003
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    Suffolk, VA
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    2,277

    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by Rusty Hills Farm View Post
    Humidity along Florida's west coast is normally quite high.
    I'm with you Rusty. This simply doesn't ring true for me. The study referenced above Kraus, and Velthuis was done in 1996 in the Netherlands with V. jacobsoni. If high humidity were a solution, then pretty much the entire southeast coast of the US would be mite free. If you don't believe me stop by for a visit in July, but bring a few extra changes of clothes.

    I wouldn't bet the farm on this......
    Horseshoe Point Honey -- http://localvahoney.com/

  14. #14
    Join Date
    Dec 2005
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    Volga, SD
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    Default Re: Something you probably didn't know about mite control

    Bear in mind that this is based on mite reproduction is reduced at high relative humidities, not mite survival. In northern states, I doubt mites reproduce much during the winter. Bees produce little to no brood during that time, too.

    The other thing to consider is that the relative humidity (RH) that influences mite reproduction is the RH in the broodnest, not the RH outside.

    This paper - http://naldc.nal.usda.gov/download/11830/PDF - includes some field study on mite reproduction, and the authors state in the paper that bees almost always maintain the RH in the broodnest between 40 and 70 percent RH.

  15. #15
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    Feb 2009
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    Algonquin, IL, USA
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    Default Re: Something you probably didn't know about mite control

    I am not trying to say that high humidity outside a hive eliminates reproduction. It is the RH inside a hive that matters.

    Bees dry nectar and to do that they must reduce the RH inside the hive, irrespective of what the RH is outside the hive.

    Therefore, it probably would not be possible to keep a hive above 80% RH for the whole year. HOWEVER, it certainly would be easy for me to do it for a good portion of my October through March. Also, no SHB during those time periods for me. That means I can probably go the majority of 6 months with very little mite reproduction!

    It is not just a 1996 study that showed this. Many studies have shown this to be true. RH inside the hive has a great effect on mite reproduction.

  16. #16
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    Default Re: Something you probably didn't know about mite control

    On another note. For all of you who say "I live in a humid area and I still have mites", I would say that relative humidity of 80% and above is probably a lot more humid than you generally experience. For example, at 90 degrees outside, the dew point would have to be 83 degrees for a RH of 80%. You don't see many 83 degree dew points. In fact, it gets very humid in the midwest from the evaporating corn. The highest dew point ever recorded in Chicago was 83. That would be a RH of 80% and a temperature of 90.

    I agree that in LA it probably is very humid most of the year, however, I'm not sure about the 80% level. I'm sure you'll hit it a lot, but it's not like it is a continuous thing.

  17. #17
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    Default Re: Something you probably didn't know about mite control

    HOWEVER, it certainly would be easy for me to do it for a good portion of my October through March. -c10250
    I'm curious: do you have much brood being raised in your hives between October and March in Illinois?

    Condensation doesn't mean that RH is necessarily high, either. I can take a cold glass into a house here in South Dakota when the RH in the house is 20 percent during the winter, and condensation will still form on the glass. Have you tried putting an RH meter into a hive to see what the measurement actually reads?

  18. #18
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    Feb 2009
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    Algonquin, IL, USA
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by Kieck View Post
    I'm curious: do you have much brood being raised in your hives between October and March in Illinois?

    Definitely not as much as in, say July, but you do get a good pop of brood starting about mid FEB

    Condensation doesn't mean that RH is necessarily high, either. I can take a cold glass into a house here in South Dakota when the RH in the house is 20 percent during the winter, and condensation will still form on the glass. Have you tried putting an RH meter into a hive to see what the measurement actually reads?

    Condensation means 100% RH. I agree with you though, just because water condenses on a wall of the hive only means it's 100% RH at the wall and maybe not in the brood nest. However, my only point about condensation was to explain why a lot of people go with upper entrances to REDUCE the RH. My point is that the RH should not be reduced, just get the water to condense on the walls instead of the roof.

    my answers are in your quote above

  19. #19
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    Feb 2009
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    Default Re: Something you probably didn't know about mite control

    Bee Culture (October 2012, Volume 140, Issue 10, p. 22) called “Varroa Mite Reproductive Biology.”

    "According to the article, mite reproduction drops significantly when the relative humidity is high. In one study (Kraus and Velthuis, 1997) at 59-68% relative humidity, 53% of mites produced offspring, whereas at 79-85% relative humidity only 2% of the mites produced offspring. Zachary goes on to explain that, he too, has had experience with this phenomenon in his lab."

    http://www.honeybeesuite.com/hive-hu...-reproduction/

  20. #20
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    Default Re: Something you probably didn't know about mite control

    O.K, but you see that mite reproduction from October (maybe November where you are?) to the middle of February is almost zero because brood in the hive during that time is almost zero, right? So how does the increased moisture in the hive during that time when mite reproduction is almost at zero anyway offset the risk to the bees of increased moisture/condensation during that time?

    If it's working for you, by all means keep doing it.

    Also, I'll agree that the RH at the boundary layer to create condensation on glass might be 100 percent, but that does not mean that the RH a centimeter away is the same. Even if condensation is forming on the walls of a hive, I wonder what the RH in the cluster or the broodnest is at that time. Have you ever tried measuring it?

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