Sugar roll test for Varroa mites
The best way to test your colony for mites is to use the Powdered Sugar Roll Test developed at the University of Minnesota. It is important to note that the Powdered Sugar Roll Test is not the same as dusting for mites and then counting bodies on the bottom board. This test is more involved and more accurate.
Click the link below to see a nice visual presentation of the steps. The part that people sometimes miss, right at the end, says this:“If you know how many bees were in your sample, you can estimate the number of mites per 100 bees. If there is brood in the colony when you sample, you should double this number to factor in the amount of mites in worker brood. For example, if there are 5 mites/100 bees, the total infestation is probably 10 mites/100 bees. If your colony has over 10-12 mites/100 bees, you should consider treatment.”
I am a newbee, but I have been thinking about this for a while, which is often dangerous. When my packages arrive in a few weeks, why don’t I “roll” them all (except the queen) in powdered sugar? They are conveniently already in a container custom made for the purpose! A dusting, or a sifting, or even a dousing of PS is sure to dislodge a large percentage (my research indicates between 50% and 80%) of mites, which, at this point are all phoretic. It seems like a no-brainer–the perfect time! But I can find nothing on the internet, and nobody who has tried it. Surely, I am not the first to think of it, so there must be a reason this isn’t recommended. Or did I just revolutionize beeginnings before I started? I would appreciate your input, as I have a great deal of respect for your work. BTW, I live in the Seattle area. Thanks.
Don’t confuse the sugar roll test, which is diagnostic tool used to estimate the ratio of mites to bees, with powdered sugar treatment for varroa mites. Maybe you’re not confusing them, but it’s not clear to me.
Anyway, there is no reason you can’t treat a package with powdered sugar. However, I think it unwise to do much to upset a new package until they have accepted their queen. In situations of stress, honey bees sometimes “blame” the queen for things that go wrong. If you start stressing them before they have accepted their queen, they may “think” she is to blame for their problems and decide not to accept her.
It would most probably work out okay, but that’s a risk I wouldn’t want to take if I didn’t have to.
Also, if the package they came in doesn’t have a screened bottom, the mites that are brushed off can just climb back on.
Here’s follow up on the idea of dusting a new package. On page 400 of the April 2016 edition of ABJ, Jerry Hayes suggested this exact thing in his Q&A column. By the way, I think the idea would be to turn the package so that one of the screens would face downward, and the mites would fall out. I guess this depends on the size of the holes in the screen.
Thank you for your work, and your great blog. I have learned a great deal. I am still learning.
By the way, I had seen hundreds of photos, and always assumed a bee was blissfully unaware of the baseball mitt-sized bug clinging onto her hair, until I saw this video:
https://www.youtube.com/watch?v=xSGa9DKraGA “Bees fighting varroa” in which it is obvious that not only is she aware, but “task-saturated” with getting rid of the bug on her back, to the exclusion of performing any other useful task within the hive. It also shows that, far from helplessly falling to their deaths when eventually scraped off, the nimble mite probably has about 35 or 87 chances to grab onto another hapless bee on its way down between the crowded frames and slatted rack to the screen below. Imagine not being able to say out loud, “Hey, I got a bug on my back! Could somebody lend a leg? Or a mouth?” Love your blog, Rusty.
The placement of the parasites in the video reminded me instantly of this post: Hourglass bees. That is the exact spot the bees can’t reach to groom themselves.
I finally received my packages yesterday. The whole family was so excited. I performed a sugar roll test first thing, you know, to establish a baseline. I didn’t get any mites! Not one! So now I am wondering if I did it wrong, or if there just weren’t any in the sample, because at this point, there aren’t any hives that don’t have mites. Are there?
You probably did it right. It is possible the packages didn’t have any mites because they may have come from treated hives. But that doesn’t mean they won’t get them later. They pick up mites from flowers and from drifting workers and drones. Monitor again in early fall to see where you are, or earlier if you are curious.
Presently I have 3 hives. I have read up on various methods related to treating hives for Varroa Mites and I am leaning towards using the Oxalic acid dribble. My question relates to my honey supers. I have 2 deeps boxes and one medium honey super on each hive. The Frames in the supers are just about full. I would like to leave the supers on throughout the winter and allow the bees to have the honey rather than harvest it. I still have a surplus of honey from last year and want to make sure the bees have enough stores to make it through the winter. I live in CT and the winter month here are unpredictable. When I treat the hives for varroa using the dribble method, could I treat both brood boxes and then just place the honey super back on the hive? If the honey goes unused by the bees over the winer could I then harvest the honey from them in the spring or is the honey now tainted due to the Oxalic acid that was used when I treat the hive. Thanks for all the information that you provide on beekeeping.
That’s a complicated question which requires reading between the lines. The EPA label, the ultimate authority in the US, reads, “Do not use when honey supers are in place to prevent contamination of marketable honey.”
However, oxalic acid is a natural component of honey, and it would be essentially impossible to detect any “extra” that got into the honey because of the treatments. In fact, if the honey is capped, it probably wouldn’t get into the honey at all, just like oxalic acid won’t get under the brood caps and kill the mites inside.
Still, I wouldn’t break the law. The label says “marketable” honey. If you aren’t going to market it, but rather just eat it yourself, you wouldn’t be breaking the law. I would certainly eat honey that way. I’m quite sure the only reason the EPA prohibits honey supers in place is because the extensive testing required to label it as safe for use with honey supers hasn’t been done. Why? No one wants to pay for it. OA is cheap, so no one will get rich by doing all the tests and then selling it. I imagine the label will remain as is for a long time.
The other thing you can do is take off the supers, treat, and wait a week or so before putting them back on. That way, all the OA will have been absorbed. The EPA doesn’t say when you can put the supers back on, so I would assume that you can do it almost immediately. If it had to be longer, they would have said so. The down side is unguarded honey supers can be attacked by moths and beetles, so they would have to be stored carefully.
So I treated my hives for 3 weeks with ApiLife Var (instructions said 4 weeks but I ran out). The mite count was very high when I started, like 100 a day on one check. There were not thousands of mites when I took the varroa board out at the end of the 3 weeks which got me worried as I saw your post talking about something similar until you used leftover Hopguard. But perhaps they were eaten by ants?
Anyway I’ve just done a sugar roll test on my largest hive. I look the bees from the middle of 3 brood boxes so probably a mistake there not taking them from the brood nest, and I overestimated the number of bees and think I took 8-9 fl oz so 800-900 bees. I found 3 mites with this check so about 7 mites per 1000 bees once you double the number to include the brood. I cannot find any information on a calculator for sugar roll tests but what would you say is an acceptable amount of mites for the end of September/beginning of October or is the number 0?
Go to this Canadian site and scroll down to Table 2 (it’s nearly at the bottom). It shows treatment thresholds based on sampling method. You have less than 1 mite per 100 bees, which is just fine for winter.
I just did a sugar roll test, the last of my 42-day treatment for Apivar. Great news the mite count was @ 2 mites! After the test my friend who was helping started to freak out! Oh my God, Oh my God!! Out of the jar and covered with powdered sugar was my queen!! Four eyes checking the frames missed seeing her before I brushed the bees into the jar!! Should I be concerned that I caused her some trauma?! So, very glad I’m not a believer in the alcohol wash!!
I’ll bet your bees are glad, too. That’s so typical of queens, though. They cannot be trusted. Ever. But don’t worry, she’s probably fine.
Rusty – after reading this blog again – I took interest in watching the video posted that showed bees working at knocking off mites. Interesting. The video shows mites escape being knocked off by their posterior position on the dorsal side of the thorax. We see bees lifting legs up in an effort to dislodge mites but not successful when the mite is perfectly positioned. I’ve been doing sugar dusting and using the method to estimate the number of mites per 100 bees. It’s a bit of a stretch and maybe highly inaccurate but it is possible to come up with a number that helps give a sense of the density of mites in the hive. A sugar roll is a good test but frankly when the sample size is N=1 results are just as dodgy. So – thinking about the video – have you ever considered using your camera to determine mite levels by taking an image of frame of bees then visually counting a “sample” if not the entire frame image of bees to determine how many bees have mites being carried on their thorax? Winter is coming and I need to go through all my hives. Weather permitting the plan now is to photograph all the frames while setting up the brood boxes for winter. This time I’ll take those images and do a mite count. Look to see just how many bees have visible mite backpacks. Seems to me this could be a quite accurate method for determining numbers of mites per 100 bees. If the only way mites can hold on to bees is to be positioned such that they are not easily knocked off it makes sense most mites would be visible to a camera position. Get an image and count the bee. What do you think? Or do you think mites are carried just as commonly on the bottom of thorax which would make them unseen from the dorsal side?
I think mites are most often carried on the underside of the abdomen where they bury themselves beneath S1 and S2 so they are virtually impossible to see or remove.
I have just used the alcohol varroa mite test. I tested all 3 hives I have (I used a total of about 900 bees). I only saw ONE mite! Is this normal? Does this mean I have extremely healthy hives, or did I do it wrong?
It means that you don’t have to do anything at the moment because your mite population is currently at an acceptable level. Seems like good news to me.