Is February to early for Oxalic acid treatment for mites?

  • 03 May 2020 11:30 AM
    Reply # 8943737 on 8735734
    Allen Engle (Administrator)

    Hello Richard,

    I'm glad your doing your counts.  It's the only way to keep up on the numbers.  You're right that the mite numbers are increasing at this time of year, however the bee numbers are increasing as well, so the actual percentage should remain about the same.  I agree with you that those numbers, at this time of year and position in the population cycle indicates treatment.  The  Honey bee health coalition Varroa control tools provides a great discussion about the various treatments and counting methods...….and caveats.


    Good luck.

    Allen Engle

  • 02 May 2020 9:22 AM
    Reply # 8941680 on 8735734

    So I know this is a very late follow up but I thought it may be helpful for me to review my own actions and this may bee helpful for some other newish bee keepers. The short book is both of my remaining hives are doing well, and one is doing extremely well BUT 6 weeks after treatment with Oxalic Acid sublimation I am reaching levels where I need to treat again. Hive #1 had 6 varoa in a half cup of bees using the sugar roll method and Hive #2 had 12 varroa. Now hive #2 is very rapidly expanding so I would expect more varoa.


  • 11 Apr 2020 4:14 PM
    Reply # 8893973 on 8735734

    Hi Allen, I haven't done a follow up mite count but it's on the to do list. We got back into some cooler weather and I didn't want to open the hives enough to get an appropriate sample. The weather is now warm enough so I'll be getting to that in the next few days. I did pull 2 frames of eggs and larvae from the stronger hive and donated it to the weaker hive right after the final OA treatment to give the weaker hive a boost and I have since added another full depth super to the stronger hive as it was filling up with bees (again) and I wanted to hopefully decrease their urge to start swarming. I also popped in a few frames of foundation with hopes that when this first nectar flow starts they will start pulling wax and some of my frames are getting ready to be retired. I didn't see any swarm or succession cells but have seen a little bit of capped drone brood but no hatched drones yet. I have been feeding 1:1 sugar syrup for about 3 weeks as the one queen was in full on laying mode already. A pint of syrup has been lasting 3-4 days until just recently, just in the last couple of days both hives have started going through a pint a day. I'll probably keep up the feeding for another week and by then there should be something blooming in enough quantity for the bees. I also added a pollen patty to each hive about 4 days ago.

  • 22 Mar 2020 8:17 AM
    Reply # 8848167 on 8735734
    Allen Engle (Administrator)

    Hey Richard,

    Happy to hear about your gangbusters hive.

    What's the mite load after the three OA treatments?

    I agree with you on the solid sugar patties.  When there are other food sources, they tend to ignore them, however, as an emergency feeding in winter, I've found frequently they work.

    Have you been seeing any drones yet?

    Allen Engle

  • 21 Mar 2020 5:11 AM
    Reply # 8846628 on 8735734

    As a follow up, I did do a sugar roll test for varroa in late February and decided to treat. I have now completed my third Oxalic Acid sublimation treatment a couple of days ago (March 19th actually). One of my surviving hives (of 3 from the fall as I lost one) is just cranking!, lots of Bees, lots of flying activity, lots of brood, and lots of pollen being brought in on warm days... and they are going through their stores. I have one more frame of saved honey to give them but I plan on starting to feed 1:1 Sugar syrup in the next few days. The girls really didn't like the sugar frames and patties that I put in the hives a month ago and were either ignoring the frames or hauling the patties out.

    As I said, one hive is just expanding rapidly with lots of bees coming and going, lots of activity so all is good there. The second surviving hive is not so robust with just a dozen or so bees kind of coming in and out but without a lot of vigor. I did see the queen in the weaker hive 3 weeks ago and there was new brood and eggs but not as much as my heartier hive.  I will look for her this weekend as it's going to be over 60 degrees and if needed I will steal a frame or two of eggs and brood from the thriving hive to 1) help prevent the thriving/surging hive from feeling like it may need to swarm and 2) to beef up the weaker hive with bees, eggs and brood. I will probably notch the egg frames in a couple of places to see if the bees in the weaker hive are inclined to requeen themselves.


    Best of luck this spring y-all, it's a strange one.

    Last modified: 21 Mar 2020 5:15 AM | Richard Turner
  • 13 Feb 2020 12:13 PM
    Reply # 8745668 on 8735734

    Richard, Here is my two cents worth.  What I am about to write applies mostly to Langstroth hives. Ware, top bar, or long hives may require a little more creativity to use an Oxalic acid vaporizer.

      Oxalic acid is used in the midwinter time slot because most hives in colder climates (I think we qualify) have very little to no brood then. And, the treatment does not require the hive to be opened other than possibly temporarily enlarging the entrance a bit if you have made it very small for the winter.  Most discussions I've seen say that the brood-less (or low brood) period is late December or early January. As you suggested, that would mean that the mites are therefore riding on an adult bee and exposed to the vapor. Not protected in a sealed brood cell.  I (actually a friend cause I'm recovering from surgery) treated several of my hives this winter on February 3rd with vaporized oxalic acid. Even February 3rd might be a little late for getting the most effect from the treatment.  That doesn't mean that a treatment won't help. I had the hives treated that had higher mite counts prior to treatment with Formic Acid in August.  I figured they would benefit the most because they seem to have the least natural resistance.  I will do a mite count in March or April when the weather is warmer and we will see how things look then.

  • 11 Feb 2020 10:01 AM
    Reply # 8740362 on 8735734
    Clyde Dildine (Administrator)

    You have obviously done some excellent research and yes there is no evidence that the bees are building resistance to OA.  I personally just don't like putting anything any my hives unless I am certain it is needed.

  • 10 Feb 2020 11:32 AM
    Reply # 8738049 on 8735734

    Good question Clyde. My thinking was this. As Oxalic Acid is only affective on hatched bees (not on Brood), then an early application when the hive is essentially bloodless will be the most effective, this is also supported by most of the reading that I have done. In reading around the net (I know, that is not always a reliable source of information), there has not been a resistance to OA treatment with many years/decades of use in Europe and other countries (yet). This would be more of a prophylactic treatment to help start off the bees season in a nearly mite free state. Last year it seamed to work well but I did not do a side by side comparison of early treatment and not as I only had 3 hives. Much of the reading that I have done does indicate a late fall or winter treatment is very effective and that summer OX treatment is less so due to presence of brood. so, One treatment now or a succession of treatments later in the summer when there is brood present, or using Apivar or one of the other chemicals which I do not like to use in my hives.


    I was putting this question out there to hopefully start a discussion to get more information for myself and other back yard beekeepers so thanks for the reply and please keep it coming.


    And, no, if there were still snow and cold weather in Bend I wouldn't be thinking of this but it has been warming up lately (very early) and the girls are flying and so I'm trying to get ahead of the season. I'm hoping my bees don't just burn through their available food supplies before spring actually arrives and nectar and pollen are around so I am starting to use sugar patties and some frames of honey saved from last year and the girls are going through it for sure.


    Again, thanks for the reply.

    Last modified: 10 Feb 2020 11:35 AM | Richard Turner
  • 10 Feb 2020 9:38 AM
    Reply # 8737746 on 8735734
    Clyde Dildine (Administrator)

    My first question would be how do you know you need to treat at this time?  Have you done a mite count to determine the colonies have reached the economic threshold for treatment?  Prophylactic treating has and can lead to the bees becoming resistant to whatever treatment option we choose.  Popping open a hive to do an alcohol wash or sugar roll test even on a warmer day this time of year is very invasive and not recommended.  You can use a sticky board that will give you a general idea of your mite levels as an alternative method.  

  • 09 Feb 2020 7:27 AM
    Message # 8735734

    Hey all, I was just wondering if during this unseasonably warm weather here in Central Oregon if it would be to early to do an Oxalic Acid sublimation to treat for Varroa? I am under the impression that it is not to early and intend to do a treatment on my 2 surviving hives on the next day it cracks over 50 degrees.


    Last year I did an OA sublimation during a similar early season warm spell and I had very low mite counts throughout the summer so I'm personally under the impression that it is a good idea but are there any reasons not to???


    So Far, 2 of 3 hives are still going strong, plenty of bees and good food stores. The one hive which has not survived was my weakest going into the winter and I think they just starved out. There was still honey in the edges of many frames and a couple of nearly full frames but not right where the main body of bees was (Damn!). 

    Last modified: 09 Feb 2020 7:30 AM | Richard Turner

    

Powered by Wild Apricot Membership Software