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  Monday, 31 October 2022
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Hi All,

For a couple years now I've had colonies collapse in October and I'm struggling to identify the clues left behind. 2 of the 4 colonies from this year produced honey (Northern spring nucs) and looked pretty good going into September following a mid-summer formic treatment. The other 2 colonies were early summer splits and are doing ok, but didn't produce honey this year.

I applied Apivar strips to all hives after pulling honey in September and also supplied supplemental feeding to bolster the stores since we had a slow goldenrod flow this year. At the end of this month these two producer colonies had died, or otherwise left the hive. Little to no bees remain, but there is plenty of honey in and above the brood chambers in a medium. I feel like I did a good job with mite treatment this year and was conservative with honey harvesting, in addition to feeding this fall. Why would colonies disappear at this point in the fall? Is there something or a combination of things that are red flags that I'm not seeing?

Thanks
3 weeks ago
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#2897
Most likely Varroa...even though you treated. Same thing happening up here. Lots of seemingly healthy colonies gone in October.

The problem is using treatments that don't work well enough. Apivar (amitraz) has lost it's effectiveness. Formic isn't working as well as claimed. I don't really know what you can do at this point. The only way I've been able to recover my apiaries in the spring is to make nucs in June and July, and winter hundreds of nucleus colonies. The nucs are able to keep varroa load down to manageable levels, make a crop, and do well into the second year.

Sorry about your losses, but we're all on the same discouraging boat.
3 weeks ago
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#2898
Hi Mike,
Thanks for your insight. I was suspicious that varroa was the likely root cause, but without a way to prove it, or substantiate with other experience (like yours of course) I was at a loss. I'm just a backyard hobbyist, but what you describe sounds like a recent evolution of the battle against varroa. Is that true? I assumed that the commercially-available miticides were effective enough, but what you're suggesting is that is not the case, or less the case today. This shift in effectiveness is a major threat to the economic sustainability of any size apiary!

For a location like mine (heavily forested central vt) where we rarely see a honey flow in the early summer, and almost exclusively rely on the goldenrod and aster flows of September, the bee population management (and hence mite population management) scheme needs to change. Following your model of making tons of nucs in preparation for a summer flow the following year, with the assumption that those nucs will suffer heavy losses in the fall/winter works if the location provides a honey flow before the nucs are made. I'll need to figure out how to orchestrate the brood breaks to both reduce the mite loads (and virus loads), and have large enough colonies for September honey production. Timing seems to be the next challenge, on top of implementing adequate mite treatment(s).
Hi James,

A key step in varroa control is to do another mite count after each treatment period to be sure the mite count got down below the treatment threshold. Choosing the correct type of treatment for the situation is important but as Mike noted, sometimes the treatment of choice doesn't do the job as well as it needs to. Post-treatment mite counts will tell you that so you know if the colony is okay for the time being or if you need to do more on mite control then. All of that said, a researcher in a recent Zoom session noted that if the virus load gets above a certain point due to a high mite load (he defined that as viruses adversely affecting more than 10% of the population of bees), the colony could still fail even if you manage to get the mite load back down. Once the virus load is up, there's nothing you can do but hope for the best. The takeaway was to monitor for mites early (June for us) and monitor regularly treating to control mites if the counts go above 1%.
What's interesting is that small colonies seem to be able to survive but when put into a 10 frame hive the following spring greater numbers fail soon after fall harvest. Colony size and age of queen seem to be the only difference.

A good study would be to manage a number of nuc stacks into the second year, harvesting brood to manage swarming and retain the queen. Compare with overwintered colonies that are placed in 10 frame. Same yard, same stock, same age of queens, same management, and see what happens that fall and following spring as to losses from each group.
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