# winter time natural mite drop in a highly mite tolerant colony



## Fusion_power (Jan 14, 2005)

I cleaned and replaced bottom boards, brood chambers, and put new Killion bottom boards on all my colonies just over 5 weeks ago. In the interests of understanding mite dynamics in a tolerant colony, I pulled a bottom board today and counted the number of mites. On the entire bottom board, I found 15 mites. There were also 12 dead bees and about a half cup of wax debris. This was going over it with a fine tooth comb and a large magnifying lens to ensure I did not miss any. In one 6X6 area right beneath the cluster, there were 3 dead mites. The cluster at 32 degrees is just a tad smaller than a soccer ball. So somebody analyze what it means when you find 15 mites on the bottom board after @35 days. Does anyone think this colony is in trouble? Would it help if I said that they have been totally untreated since 2005?


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## Solomon Parker (Dec 21, 2002)

That sounds pretty normal to me Darrel. That's every winter.


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## burns375 (Jul 15, 2013)

Mite drops have gone up the last 2 weeks in my hives, in january/february i saw maybe 1-5 per week. Currently the large ones are 15-5 or so per week, smaller 5-0 week. The hives are screened bottoms with inspection boards.

Not sure what it means, i posted the question didn't get much of a response. I figure the mites born during warm weather of dying of old age. I wish i knew an easy way to determine a mites age under a loupe 

During summer levels were lower than "treatable" thresholds, somewhere around 5-15 mites/day in fall (peak levels)


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## enjambres (Jun 30, 2013)

I have been searching for information about mite drop counts taken in winter. Apparently almost no one does this, and the general notion is that the counts are considered even less "reliable" in winter than in summer.

One study I did read noted that the natural die-off rate of mites in winter was approximately 1/3 of that during the during the summer. (In other words mites live longer in winter than summer, as do winter bees compered to summer bees.)

But there is no info, that I have found, to evaluate the mite drop numbers in winter. Speculation is that mites do not fall off at the same rate in winter due to less movement by the bees. Or if they do fall off would quickly fall on to another host, with little risk of winding up on the sticky board instead. 

And of course the conventional sticky board readings are done during the period where the mites are mostly (in terms of percentages of the total mites within a hive) holed-up inside cells vs. phoretic ones. It would seem for that reason that numbers found on the boards during the broodless period would represent a larger share of the total mites in the hive (more representative sample of the total mites on bees in the hive), since none could be in the cells. But whether that corresponds to the rate the colony is (more or less) parasitized by the mites is not clear.

My most recent count (Jan 14 -31) had daily rates of 1.29, 1.1 and zero/ day, repectively. Mine have resumed brooding, based on a few dead pupae among the dead bees at the bottom of my hive (none with any visible mites or mite-damage, examined under magnification). The prevous two-week interval the numbers were 5, 3, and 1.

My hives have had (in same order as above) one treament of Apiguard, one-half treatment of Apiguard and no treatment.

This is certainly an area where there is a significant lack of data, which is a pity because even in very cold climates (like where I am in northern NY) sticky-board monitoring could be done with little disturbance to the bees. And since during broodless periods, all of the mites would be phoretic, it seems an excellent time to evaluate the base-line level of parasitization of the colony, independent of any treat/no treat decision.

If anyone knows of ways to assess the winter- or broodless-period mite drop levels, I would be very interested to read about that.

Enj.


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## Duncan Thacker (Feb 4, 2014)

I would be happy to explain mite counts to you. Mite checks are done daily divide the mites by the days since you last counted and you will get the daily average mite drop. you have less than one a day. which would be well below the economic threshold. The problem is you use this information to gauge weather or not to treat before the bees start thinning out their population in prep for the winter cluster. In a cold environment we would not count or risk opening the hive.

You are lucky in my opinion you don't have to deal with sever winters where you live, well maybe a polar vortex now and then..


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## Duncan Thacker (Feb 4, 2014)

burns375 said:


> Mite drops have gone up the last 2 weeks in my hives, in january/february i saw maybe 1-5 per week. Currently the large ones are 15-5 or so per week, smaller 5-0 week. The hives are screened bottoms with inspection boards.
> 
> Not sure what it means, i posted the question didn't get much of a response. I figure either the mites born during warm weather of dying of old age. I wish i knew an issue way to determine a mites age.
> 
> During summer levels were lower than "treatable" thresholds, somewhere around 5-15 mites/day in fall (peak levels)


watch the one averaging 5 a day.

The mites life cycle is too short to worry about age....watch that drop it is directly relative to the mite population.


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## burns375 (Jul 15, 2013)

Duncan i think most of us understand how to count and the fallacies around inspection drops vs brood nest rolls. Fusion power and others are looking for insight around the value and meaning of winter counts. If there is a translation. Im seeing obvious trends between hives... perhaps in spring with continued monitoring somekind of rough transfer function between winter and summer levels can be obtained. Perhaps someone has already done that work, but not much data on the subject is found on the interwebs or local clubs.


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## Duncan Thacker (Feb 4, 2014)

enjambres said:


> If anyone knows of ways to assess the winter- or broodless-period mite drop levels, I would be very interested to read about that.Enj.


In NY you will never open a hive in winter. If you have drops like you got now going into winter there is no need to worry about mites you have done all you can.


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## Duncan Thacker (Feb 4, 2014)

burns375 said:


> Duncan i think most of us understand how to count and the fallacies around inspection drops vs brood nest rolls. Fusion power and others are looking for insight around the value and meaning of winter counts. If there is a translation. Im seeing obvious trends between hives... perhaps in spring with continued monitoring somekind of rough transfer function between winter and summer levels can be obtained. Perhaps someone has already done that work, but not much data on the subject is found on the interwebs or local clubs.


The only way I see for us to get the winter levels is to wait until we open the hives in the spring count and do the math. So the best we will get is a daily winter average. I don't know about you but I am not willing to open a hive in the winter not even to slide a tray out.


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## enjambres (Jun 30, 2013)

@Duncan Thacker:

I am puzzled, I live in northern NY, a much colder climate than KY, but think that pulling a sticky board creates almost no cold-temperature disruption to the bees. I just remove the foam-wrapped stick that closes the slot, reach in and slip the board out and pop the closure back in while I take the board off to the indoors to do the counting. The bottom of the hive is open only for less than 10 seconds during removal and reinsertion. Of course I choose the warmest (and 25F counts as heat wave here at this season) and most windless day to pull the boards. I do run a solid board under my SBB, but if I didn't, I would simply exchange the sticky board with another non-sticky one while I take the mite-count board off for counting. 

I do know how to do the math on the counts (mites/days since last count = mites/day, averaged). 

But I disagree that the mite drop numbers can only be used in the fall for treatment decisions. I simply think that no research has been done to study the rates of mite drops in cold weather when all the mites in the hive are phoretic mites and what levels of parasitization those numbers represent, and more critically, what the risk-scale, or prediction of risk for a given average number of mites/day counted during winter might be.

By concentrating soley on the "economic threshold" (an odd concept since the cost of treatment is quite varied, both in terms of bees killed by treating and the cost of the chemicals used vs. cost of loss of honey production or of the colony itself) I think potentially valuable information is being ignored. And that info would be even more valuable for people like me who are trying to figure out the best path towards the least, or no treatment, practise.

Enj.


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## Fusion_power (Jan 14, 2005)

I looked up in my records to see when I swapped the bees to clean bottom boards. It was December 21st. That was 48 days ago. So that puts my mite drop levels at 15 mites in 48 days. Keep in mind that this colony is very mite tolerant. I don't expect to find many. Also to answer the question about how long mites live, the average is about 90 days though some made it longer. I have not seen a study of mite longevity in winter so can't say if it is different from summer levels.

Here is the record: [12/21/2013 3:06:23 PM] I got 4 colonies switched out to new woodenware and have one more on the porch that needs to be overhauled, but can't do it until the bees settle down for a day or two.

The switch out was to all refurbished or new brood chambers, new Killion deep bottom, and scraped and cleaned bottom board.


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## squarepeg (Jul 9, 2010)

darrel, did any of those mites you found appear to have been chewed?


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## Fusion_power (Jan 14, 2005)

I would need a low power microscope to check and currently don't have one.


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## squarepeg (Jul 9, 2010)

understood. i saw a lot of allogrooming at the entrance of one of my hives a couple of weeks ago.


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## Juhani Lunden (Oct 3, 2013)

enjambres said:


> I have been searching for information about mite drop counts taken in winter. Apparently almost no one does this, and the general notion is that the counts are considered even less "reliable" in winter than in summer.
> 
> One study I did read noted that the natural die-off rate of mites in winter was approximately 1/3 of that during the during the summer. (In other words mites live longer in winter than summer, as do winter bees compered to summer bees.)
> 
> ...


I have no hard data, but a bee researcher in Finland once said to me, that in broodless period the mite dropping is maximum one fifth of what it is in summer. * He also said, that the loss of mites in winter is about as big as the loss of bees. About 40% of the bees are lost, and equally of the mites, in winter.

*
1 mite/day dropping in summer= 200 mites in the hive
1 mite/day dropping in broodless period= at least 1000 mites in hive

We have broodless period from October to February. Bees are not able to fly from end of September to late March.


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## Duncan Thacker (Feb 4, 2014)

enjambres said:


> @Duncan Thacker:
> 
> 
> I do know how to do the math on the counts (mites/days since last count = mites/day, averaged).
> ...


I don't remember saying Only in fall, just concentrating on that particular critical period because we are talking about winter. I monitor daily, even a TF colony can catch a curve ball which may affect the host parasite relationship.

You are right any information is valuable. Not opening the hive in winter has been drilled in me since Grandpa first showed me a hive. Usually I just go out put my ear to the side, rap it once good and listen for the roar. I pride myself on thinking outside the box so, you convinced me I'll give it a try.

My worry was changing the hive environment and causing the bees to use more stores. I have no idea how long it takes a colony to bring a cluster to the 90's in winter. I'm only going to open half so I can compare to the other half come spring. But it will have to wait till next season. I already have them committed to another venture this coming season.

I was raised in NJ. Stationed at FT. Drum

Looking forward to hearing your results


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## Duncan Thacker (Feb 4, 2014)

Fusion_power said:


> I would need a low power microscope to check and currently don't have one.


A good magnifying glass will do


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## Fusion_power (Jan 14, 2005)

I have a very good magnifying glass. You can see much finer detail in a microscope. A cheap kids microscope is perfect, something about 30 up to 300 power.


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## beekuk (Dec 31, 2008)

Here is one of the calculator things that has winter months on it, although i don't find the natural mite mortality drop counting a very reliable indicator of overall mite numbers.

https://secure.fera.defra.gov.uk/beebase/public/BeeDiseases/varroaCalculator.cfm

Also a small study of winter mite mortality, old paper, and inconclusive.

http://hal.archives-ouvertes.fr/docs/00/89/16/80/PDF/hal-00891680.pdf


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## Fusion_power (Jan 14, 2005)

Interesting results beekuk. I put it in with 10 mites over 31 days and it said to treat them in 6 months. I will never treat them because they will never need it, or if they do, they will die.


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## burns375 (Jul 15, 2013)

Duncan Thacker said:


> The only way I see for us to get the winter levels is to wait until we open the hives in the spring count and do the math. So the best we will get is a daily winter average. I don't know about you but I am not willing to open a hive in the winter not even to slide a tray out.


Perhaps a little too cautious, like a new mother. Sliding the board out is just fine, most of the hives are in the 2nd box anways. I and other club members have wintered hives with the screen open all winter liong.

Popping the inner cover is no biggie eutger such as in an emergency feed situation...I wouldn't pull frames to do a roll unless it was sunny, no wind around 55-60F


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## Duncan Thacker (Feb 4, 2014)

My previous thinking was cautious because I use TBH's opening it up gives me visions of a wind tunnel. I am still cautious. In regards to the winter mite count there was no necessity, (if it isn't broke don't fix it) principal. Got to do the risk assessment and decide then.


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## Solomon Parker (Dec 21, 2002)

Why all the fear about opening hives in winter? My hives get opened half a dozen times every winter, virtually always in freezing conditions.


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## beekuk (Dec 31, 2008)

Solomon Parker said:


> My hives get opened half a dozen times every winter, virtually always in freezing conditions.


 Why is that Solomon, out of interest.


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## Solomon Parker (Dec 21, 2002)

I check the size and vitality of the cluster and also remaining honey. I've given up preemptive feeding.

Bees don't fly when it's freezing.


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## enjambres (Jun 30, 2013)

It's reassuring to read that more experience beekeepers do occasionally open up their hives in the winter. (Because I have shocked a few local beeks when I reported that I had done so.) But I think it does matter where you are. And Arkansas, even in depths of a cold snap, doesn't have the sustained bone-cracking cold that I have in northern NY, when it doesn't break freezing for weeks at a time, and regularly goes below zero at night.

I have had very cold daytime temps this winter, so I carefully choose when I open the hives, and of course the temps and wind speed come into play, but I haven't seen it to be a big issue in the very short periods I have needed to have the lids partially open. And I try to catch a day when it's as warm as possible (30s), and without any wind. I am concerned about not prompting any of the bees to fly out in these temps more than anything else, because I think it would be certain death for them. If one does fly, I try to track it down and pop it quickly back through the vent hole. I am not separating the hives' boxes, or messing around with moving the frames, just opening the lid to check on and add sugar, removing the entrance reducer to sweep out any carcases from the floor and pulling and replacing the sticky boards every couple of weeks. And I often remove the partial-cover on the upper entrance hole so I can shine a red light in and admire my bees having a grand old time milling around and eating Laurie's Sugar Blocks. It gives me my "bee fix."

The chief barrier for me is that I have my hives insulated and wrapped in complex ways so any peek takes awhile to prepare for and then button up afterwards. Sometimes, like today, I content myself with just removing a few wind baffles and snaking my bare finger tips in to the outside of the reduced upper entrance - if I feel hot air wafting out the vent hole, then I know I've still got bees, close by.

Enj.


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## Fusion_power (Jan 14, 2005)

Here are two pics of the colony that I started this thread about. The frames are alternated with a comb full of honey and an empty comb in the shallow super. The super has 10 frames, the brood chamber beneath has 11. The bees were in the bottom brood chamber until today. This cluster is a bit smaller than a soccer ball at this time. The bees are healthy and ready to kick into brood rearing.


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## enjambres (Jun 30, 2013)

How I envy your chance to have the hive open and looking down at the cluster! Perhaps I'll get an opportunity to do that sometime in the next 5-6 weeks. Quick little peeks as I shove in the sugar bricks are just whetting my appetite.

Enj


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## Solomon Parker (Dec 21, 2002)

Great pictures Darrel, that's exactly what I look for. If the frames are lined up, you can see down several boxes. From this view you can see the size and vitality of the cluster and the amount of honey left.


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