Winter Bee Death- Many Hives- Unknown Cause
For the past 3 or 4 years, once I took winterizing my hives more seriously, I have had very few hives not make it through the winter. Last year, out of 16 or so, I had no hives lost. The year before, 1- by starvation. But all other hives have survived. I have had plenty of problems in Spring and Summer with other things, like losing queens, but I was hoping I had the winter thing figured out.
Primarily, I though (and still my be true), because i had started to provide insulated ventilation, and a constant source of added food. Plus, a top-of-the-hive open space, about 1 1/2" tall, where bees congregated enmasse. The system seemed to be really working (described in other posts). I have not idea if the open top space had any impact- but was thinking it might- intuitively it seemed healthier, and all the hives used the space.
However, this year I have had a few signs that I might not do so well- and winter hasn't even officially started (at least, when i started writing this). Out of 20 hives, I have seen significant bee death in 7 hives. In the others, very little (so far- I have to recheck this week). All of the 7 seem so small to not be able to make it through the winter. This is astounding- and mystifying- and frustrating. Plus- with the few other beekeepers I have spoken with- they are experiencing even worse losses up here.
In each of these hives, the bottom screens have been packed with dead bees, which I cleaned out. Of course, there are always dead bees in Fall and Winter- but these are very large losses-many pounds, and it is not at all obvious what is going on. They are dry, have plenty food close by, have had mite and Nosema treatments in Fall, and were fed. All were strong two months ago (or seemed so). All had queens less than two years old. There does not seem to be an obvious culprit. No diseases that I can see- no sign of anything, but dead bees.
We have had massive amounts of rain- and a sort one week cold snap. My first guess- and right now, best guess, is the cold snap is the culprit. I am totally speculating, but I think the bees were vulnerable when it happened- not clustered- and the moisture, due the heavy rains, was high in the air when the cold came. Possibly- a guess- these hives died of exposure inside the hives. I have never heard of it, but this is very much an unusual year.
In reading Randy Oliver's site, he described some usual cyclical hive behavior from Nosema ceranae, which i had never heard of, and fit the picture (in a scary way). He described N. ceranae as an asymptomatic disease- but with a two year cycle in a hive, where the second year they bees massively raise brood in the summer in response, and then crash the following winter. I saw massive amounts of brood this summer- and am now seeing death. So- this seems like a candidate (though I treated with Fumigillin- but maybe not enough?). I followed Randy's advice to look for it with a microscope. I have not found it yet- but have not given up the search.
Next steps are to send samples to WSU and/or the USDA, but they only look for Nosema, tracheal mites, and Varroa, so I am not hopeful. Very sad- my best friend beekeeper- whom I learned this from and has kept bees for 30 years or more- says he may give it up this year. That's a big deal- and I can totally understand why.
Below are some images from the search for Nosema.
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| Bee guts at 40x-searching for Nosema |
Primarily, I though (and still my be true), because i had started to provide insulated ventilation, and a constant source of added food. Plus, a top-of-the-hive open space, about 1 1/2" tall, where bees congregated enmasse. The system seemed to be really working (described in other posts). I have not idea if the open top space had any impact- but was thinking it might- intuitively it seemed healthier, and all the hives used the space.
However, this year I have had a few signs that I might not do so well- and winter hasn't even officially started (at least, when i started writing this). Out of 20 hives, I have seen significant bee death in 7 hives. In the others, very little (so far- I have to recheck this week). All of the 7 seem so small to not be able to make it through the winter. This is astounding- and mystifying- and frustrating. Plus- with the few other beekeepers I have spoken with- they are experiencing even worse losses up here.
In each of these hives, the bottom screens have been packed with dead bees, which I cleaned out. Of course, there are always dead bees in Fall and Winter- but these are very large losses-many pounds, and it is not at all obvious what is going on. They are dry, have plenty food close by, have had mite and Nosema treatments in Fall, and were fed. All were strong two months ago (or seemed so). All had queens less than two years old. There does not seem to be an obvious culprit. No diseases that I can see- no sign of anything, but dead bees.
We have had massive amounts of rain- and a sort one week cold snap. My first guess- and right now, best guess, is the cold snap is the culprit. I am totally speculating, but I think the bees were vulnerable when it happened- not clustered- and the moisture, due the heavy rains, was high in the air when the cold came. Possibly- a guess- these hives died of exposure inside the hives. I have never heard of it, but this is very much an unusual year.
In reading Randy Oliver's site, he described some usual cyclical hive behavior from Nosema ceranae, which i had never heard of, and fit the picture (in a scary way). He described N. ceranae as an asymptomatic disease- but with a two year cycle in a hive, where the second year they bees massively raise brood in the summer in response, and then crash the following winter. I saw massive amounts of brood this summer- and am now seeing death. So- this seems like a candidate (though I treated with Fumigillin- but maybe not enough?). I followed Randy's advice to look for it with a microscope. I have not found it yet- but have not given up the search.
Next steps are to send samples to WSU and/or the USDA, but they only look for Nosema, tracheal mites, and Varroa, so I am not hopeful. Very sad- my best friend beekeeper- whom I learned this from and has kept bees for 30 years or more- says he may give it up this year. That's a big deal- and I can totally understand why.
Below are some images from the search for Nosema.
 |
| Possible nosema spore at middle right- but I don't know for sure (because I lack experience). If a spore, its unusual- I saw very few. |
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| Close up of a pollen grain (at first I though this was some sort of disease- as the bee's guts are packed with them) |
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| Typical view- tons of pollen, no Nosema. I have more bees to look though, but its not looking obvious. |
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