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October 20th 2011
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I've been using a Bobcat borrowed from my friends to move a semi-trailer-load of bark mulch to where it is needed. We had the mulch delivered last spring. It was actually cheaper to buy a full load, delivered, than to get a half-load. We hired a local kid to assist in spreading it, but began to realise that the job would take the rest of this fall and some time into the spring, and, besides, the pile moulds if left a long time. The Bobcat made the job easier and a lot quicker. I also managed to move some gravel and level some ashes after that job was done.
I have had a less than great opinion of skid-steers compared to articulated loaders like the Swingers we had for moving bees, but using this one has improved my opinion. It is a tough, handy little machine and could do a good job of moving hives if fitted with forks and if operated by a patient driver on reasonably smooth ground. Some sort of hold-downs would be essential, though. We found we had no use for hold-downs on the Swingers and took them off in short order once we ballasted the tires with saltwater. The ride was that smooth. This Bobcat is not a smooth-riding machine. It tends to do wheelstands and bunnyhop if not carefully controlled.
At 2 PM, I rushed over to get the drop boards to learn the latest mite-drop news, and guess what? I had forgotten to put boards back in when I pulled them out yesterday, so there are no results for today. I'll have to extrapolate. tomorrow. I suppose that I could extend the trend from yesterday right now, but the best solution is to wait for tomorrow's results and average them with yesterdays -- I think.
We had friends over for supper.
It's foggy this morning and there is a little snow on the ground.
I see the mite drop is tapering off. (Yesterday's drops are a credible fiction produced by averaging today and the day before). Another observation is that there are still quite a few light-coloured mites and I assume from that there is still more than a little brood in the hives.
Eight days have now passed since the treatment and the benchmark curves I have consulted (example at right) are flattening by this time, as is the red line in the chart above.
The example has a 78% drop, but we're only at 46% by my calculations, so it is obvious that we are not achieving the efficacy others did or that I had fewer mites than estimated. The fact that there is brood and that I am counting quite a few pale-coloured mites (30%?) means there is brood and my population estimate could be high by as much as 50%. If so, that would mean that we have achieved 46% x 150% = 69%. The thing is, I really just don't know.
Medhat wrote this on BEE-L:
I replied that they are clean. I installed the screened bottoms on Wednesday August 24th 2011, and did not add boxes likely to cause much debris, but after thinking further, I should check. The screens are currently sitting under about 200 or 300 pounds of supers in most cases, but I can just hold a hand mirror under them and look or peek into the entrances. In some cases, I may restack the hives, too, in which case, I will have a chance to examine the boards more closely.
Medhat brought up an interesting point which could be big factor in assessing the practicality of screened bottoms in commercial use.
The temperature is minus three this morning, a sure sign that Indian Summer is over.
Above is a series of shots showing a used drop board which has been counted and is ready to be prepared for another use, and the process of getting it ready to go back under the hive.
At left is the board with mites and debris. Next, scraping off the debris and then a smear of new Vaseline. Then the grease is spread very thinly with the putty knife. Only a very thin film is necessary. Last, a roller can be used to create a rough surface which catches the debris like Velcro. This last step is not necessary, but makes the view using magnification more interesting. The entire process is very fast and neat.
I have also found that rolling Vaseline with a foam roller can be a bit stiff, so have taken to using a few squirts of baby oil onto the surface as well. I don't like the smell, but the dispenser is handy. I suppose I could buy scentless next time or just refill from a mineral oil bottle.
The lines on the drop board are simply there to make examining the boards easier as they provide a track to follow when counting. Without them, the eye cannot always know where it has counted and where not.
I thought the answer to that one would be easy, but nowhere is the answer clearly explained, or exactly at which point in the development process, a mite becomes able to live outside the cell. The PDF at left comes close, but does not spell it out.
I spent the morning reading and searching an never did get a clear-cut answer explaining how to determine of a pale mite is an adult, has been mated, and is viable or not. It seems to get harder and harder to get real information on the web, as most sites seem superficial and many just repeat one another.
I did, however find various estimates for the lifespan of a mother mite and the low end is 50 days in summer. If I use that number instead of the 100 days I have always used, which probably applies to fall populations with less brood than I have, then I am approaching 92% mite kill, not 46%. I don't think so. I'm guessing that the number lies somewhere in between. If I don't count the palest mites, that would also change the results.
Bill did come across with at least a partial answer:
Here are today's mite drop results. The count is diminishing daily. I am still seeing some immature mites in the drop. I checked the screens to make sure they are open. From what I can see, there is no debris on them that would impede mite fall.
I notice there is more drop today and that the bees are more active than yesterday. Yesterday, they weren't coming out much, but today, they are flying quite a bit. The drop is up too. I am still seeing some tan-coloured and immature mites, but fewer as the days pass.
Below is the latest chart of the mite drop being recorded on the six hives in my yard. I have changed the estimated lifespan of mites in the spreadsheet temporarily to 60 days from 100 and that has altered the curve. The ultimate number has yet to be determined. The daily drop has not yet returned to the natural level observed before the treatment.
Looking at the benchmark at right, we can expect the accelerated drop to continue for several more weeks. I am stretching the comparison, though since we do not know the original drops in the sample and also our hives have some brood, judging by the drop of light-coloured mites.
At this point, I have learned some things about mite drops and sampling, even though I may not have observed and verified them myself, yet.
Here is today's mite drop charting. I went early today by three hours and adjusted the counts to a 24-hour basis. I am still not seeing live mites or any sign that they have been moving around on the drop board. Maybe it is still too cool when I collect the boards? Mite drop and the percent of live mites in the drop are said to increase with temperature.
I'm still using 60 as a multiplier and I see that, arriving at the 90% estimated mite kill which using that multiplier gives, we are ahead of one benchmark (right). That benchmark shows about 83% kill on day 11, so 60 may be may be too low, but our estimate is right in line with the other benchmark (the lower, pink line on image at left) which also shows 90% on day 11.
I am still seeing some pale mites, but fewer. The multiplier is not simply a guess at average mite lifespan, but a parameter which also must include in some consideration of the non-viable short-lived young mites in the drop.
By all accounts, it seems the oxalic vapour treatment effect is pretty well over by day 15, and for all intents and purposes completely attenuated by day 21. Thus it seems that a repeat treatment could take place any time after day15, but it seems to me to be prudent to wait a bit longer to be sure that brood rearing has ended to whatever extent it will. By the end of the first week in November hives should be a close to broodless as we will be.
I had enough -- I know when I have cabin fever -- and went to Airdrie to do some shopping,.
I bought some groceries and looked a flat screen TVs. I never and I mean never watch TV, but do watch Netflix on my comp
As I noted yesterday, I've been obsessing about the varroa drop. Maybe it has to do with the loss last winter; maybe it has to do with not having spotted any earlier, then finding that I may have been missing them; or maybe I just have too much time on my hands.
What ever the reason, I am now somewhat satisfied that the mite loads are less than I feared and nothing like the mite loads last fall. I'll keep checking, but maybe step back to sampling over two or three days at a time. I'll also keep wondering why I don't see any live mites in the tray.
At this point, I would really appreciate any comments or questions. Please feel free to post them in the Honey Bee World Forum or write me. As you can see, this has been quite a voyage of discovery and I am finding there is a lot I don't know and can't (yet) find out.
I know that quite a few people these pages and wonder why only a few post in the Honey Bee World Forum. It is a great place to comment. Is there a problem with registering or something else? If so, please write me and let me know.
The drops are slowly tapering off. I'm still seeing some immature mites on the board, but nothing alive. I think that I'll have to really smear on the oil and see what happens. The thing is that oil will kill them, so what will I learn, except maybe see a higher count? Again, the image from Jean-Pierre is offered below. I'm seeing the full range except for the ones left of the cut-off line. On one board, I counted 1/4 of them coloured like the one just right of the line.
Here is an illustrated sequence showing the development of the bee along with varroa in a cell.
Begging pays off! Here are some promising references:
I found a good way to search for these studies. It seems that cutting and pasting the title of one study into Google often brings up other related papers since those exact words appear in the bibliographies! Otherwise, the same result might be so far down the search results that I never see it.
Today the trend continues down. I decided to assess the number of younger mites in the drop and here is what I see:
That indicates to me that some are still hatching brood and some are almost broodless. The conclusion in my mind is that to use mite drops, a qualitative assessment must accompany a count to get a closer interpretation.
The estimated kill is now at 95% and mites are still dropping, so I think my mite load estimate was low and will need a slight adjustment.
I also see a cumulative average drop of 773 mites per hive and that works out to 773/35000=.022 or 2.2% based on an estimated adult bee population of 35,000. The highest drop was 1160 in hive #2 and the lowest 393. The 1160 means that the mite drop so far represents a number equal to 3.3%of the estimated adult bee population. Hive #2 has very few young mites dropping, so probably has little brood. I'll have to take a look at it when I get a chance. The 393 is hive #1 and it has only 3 dropping today and 2 of them are young.
The hive scale reading has dropped by 13 pounds since the 18th. There are three good hives and goner on the scale. 13/(26-18)/3=about a half-pound a day per hive.
After I did the drops, I drove top Calgary for an eye exam, then did some shopping, arriving home around 8:30.
I've been assuming the populations, and hive condition for the six I have been monitoring, but I'm thinking it is time to lift some lids and see if I have been making false assumptions. Maybe the hives have dwindled since I last looked. Maybe the populations are not as assumed. After all, my calculations depend on the hives having populations around 35,000 bees. I'm going to look stupid if I am 'way off.
I am also still learning how to make a drop board that catches everything, but is easy to maintain. Yesterday, I discovered that mineral oil soaks into the masonite over a few hours. I suppose that after a while, the board will be saturated, and I do still use Vaseline, but if the board does not stop mites in their tracks, it will give inaccurate counts.
I adjusted my multiplier to 65, since the plot indicated we are approaching 100% kill, but we cannot be. There are still mites falling.
We are now at day 14 and since the worker bee capping period is 12 days, and since the mites go into cells just before capping, any foundress mites emerging from this point on should have been exposed to the oxalic vapour, and we should start seeing a decrease in young mites -- if the mothers were affected by the treatment.
* * * * * * * * *
I checked the hives quickly for populations and I think my guestimates are close. The weakest of the mite drop hives is in two boxes, weighs a ton and has bees showing on the bottoms of six frames when I tip it forward to look. Their floor is clean, as we can see (left). We can also see that a few mites land on the sides and the front and back of the bottom board and if a mite that lands there goes through the screen, it is only because a bee did not carry it out and it got brushed onto the screen or dropped by a house bee. At right is what I see if I peel back the pillow on another of the hives. Nine frames with bees, and more below, I am sure.
Mid-afternoon, I decided to start preparing the hives for winter. As mentioned previously, some hives have newly-drawn comb on top and I am planning to put that on the bottom and put the established brood chambers on top. I began, and the first hive I looked at was a drone layer. No very encouraging.
It is also chilly, with a north wind blowing. The bees are active though and it should all work out fine. I don't plan to do more than a few today.
* * * * * * * * *
I have 12 hives ready for winter now, so I'm almost half done. They range from one which is five high to one which is a double. I may move them to a more sheltered spot before winter sets in. Maybe I should add a box of feed under the double, too. Right now, though, it is in my varroa drop experiment and I don't want to disturb those colonies.
In moving the hives around, I separated a number of boxes so I could carry them, and can see that the hives are strong. Interestingly, the top boxes are heavy, packed with feed and the bottom boxes are relatively light. The bees are typically clustered in the bottom two boxes. This would have been a perfect chance to to do oxalic acid drizzle since exposed the tops of the boxes. I placed the top boxes, which are packed with honey on new comb onto new floors and then reassembled the rest of the hive on top, taking care not to interchange or rotate the other boxes.
I did not pull frames. My intent is to cause as little disruption as possible, and to leave as little damage for the bees to fix up after as possible, since it is late in the season.
The EPS (BeeMax) boxes separate quite nicely and are not suffering damage if I am careful to slide the hive tool in far enough and to be careful how I pry. If the frames bottoms are stuck to the top bars below, which on occasion they are, prying carefully between the frames through a 2 inch crack at the front, created by lifting the front of the upper of the two boxes a bit, separates them with little problem.
These BeeMax boxes are not strong and I exercised caution lifting them and them putting down. The new Meijer EPS boxes are far stronger and can be handled more roughly, but are still not quite as tough as wood for taking abuse. EPS dents more easily than wood. This does not much matter except on the mating surfaces where a bad dent would lead to a poor seal.
A bit of air leakage might not necessarily be a bad thing, since I noticed a lot of moisture under the pillows on tall hives. I had closed all the auger holes and decided to open them again. EPS hives are quite airtight and they need some ventilation. I did not have good luck with the EPS boxes until I drilled 1" auger holes in the front and back of each. I close the back holes and any front holes I want to close up with 1" Caplugs.
This morning is cool, dark, and a bit breezy. I went out and got the drop boards. I have to say that today, with thick Vaseline, they are hard to read. The mites tend to fall edge-down and that makes them hard to identify. They are very thin. The Vaseline is very shiny, too and the reflective surface adds to the difficulty. I'm seeing fewer young mites now, as expected. I don't know if I caught any more mites than I did with less grease.
The counts have not changed much from before the treatment. If indeed there was 92% kill, though, the drops should diminish from the beginning drops from before the treatment. Using today's drops and a 65 multiple, as I would for natural drop, we still predict a total mite load of 1040 average and that is still 3%! The 65 multiple should be high, though, assuming that the fumes reduced mite lifespan, but I just don't know. Time will tell.
When I went out to get the boards, I found that I had forgotten to place a board under hive #3, so I just used the average for that hive from the past two days in the chart to keep the place filled and to compute the average.
I see the drop is slowly decreasing. The young mite count is going down in the hives, too, but I am still seeing some, so there is still brood hatching.
I'm tempted to put a strip of Apistan or Apivar into one of the monitored hives -- or all of them, just to get an idea of what the residual population of phoretic mites is, but I am holding off. We plan to treat again, too, once the brood has all hatched, and I think the continuing drop of pale-coloured mites is an indicator that hives 3, 4, and 5 still are hatching brood.
My two benchmarks differ on their efficacy at this point, with one showing 96% of mites killed and the other showing 86% dead. I'm just using these charts for reference curves and have no real idea what efficacy we have achieved here, but assume that our curve should have a similar shape, which it has so far.
Both curves are for colonies with no brood and we do have some brood, so the fit is not perfect, and could be a ways off, especially as to the end point. Even if we have the same kill curve, we might still conceivably have 50% of the mites left in the hives with brood.
I have been noticing dents in the top surface of some of the paler coloured dropping mites. As I continue this investigation, I find that observe more.
Yesterday, it was unexpectedly warm and there was some robbing in the yard. I had not reduced all entrances equally and also, I had opened some top holes to reduce moisture. and the hives with screened bottoms seemed to be getting attention. At any rate, I am wondering if the markedly higher drop may be the result of the defenses or mites from robbing bees. I found 10 or more bee legs on some of the boards, and figure this must be from tussles between guards and robbers.
Also, I noticed a lot more uncapping debris than usual on the boards, since the colonies were very active and, I assume, rearranging stores. Some could have been from surreptitious "progressive" robbing, particularly where I found entire cappings on the board.
Today turned out to be warm, too, and I'm wondering if I should be charting temperature as well as drop. Could they be related?
I changed the oil and the thermostat on the red van this afternoon after we returned from Three Hills, but did not do anything to the bees today except change mite boards.
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