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A Ton of Dead Bees At the Entrance

Hello all fellow beekeepers,

I know it’s really late in the beekeeping year if you live in an area that already got snow. I live in Maryland, and due to a couple setbacks involving queenlessness (3 times!) resulted in treating for varroa rather late in the year. I did a powdered sugar varroa test, and there were a LOT of varroa. I got ApiLifeVar strips, which are more like wafers. I have one Carniolan hive, now with a laying queen (finally), and I applied two wafers of the varroa treatment on top of both my boxes on November 19th; I have a deep box with some brood and a medium super filled to the brim with stores.
Now, especially after I put in the bee meds, I’ve been seeing a ton of dead bees laying in front of the hive. I don’t see any deformed wings, or varroa mites on their backs. They are not fat drones, they are little workers. Did they get cold and die, and then were pushed outside by their sisters? Did they attempt to forage, but couldn’t quite make it home on a cold day? Are they diseased and I don’t see it? Is the medication doing something to them? The weird thing is, sometimes among the dead bees I see healthy looking larvae, just nearly developed, some still wet from just emerging from their cell. It’s really sad, but I don’t know what to do about it. I am going to reapply some more ApiLifeVar in a few days. I still hear a low hum from outside the hive, so they are probably in a tight cluster. We’ve had several days less than 50 degrees Fahrenheit, so I can’t really do an inspection in that cold. Thanks in advance for any help and suggestions; I really don’t want to lose my first hive.

Hi there, Kat. Sorry you have so many dead bees. :cry: There could be several reasons. Here are my top ones:

  1. Cold causing condensation to drip on the bees, chilling and killing them. Have you considered a moisture quilt and perhaps wrapping the hive?
  2. Robbing - seen any fighting at the hive entrance? Have you reduced the entrance to 3" wide or less for winter?
  3. Varroa despite your treatment. There is quite a bit of evidence that Thymol-based treatments (like ApiLife Var) work better in warm weather, and don’t work well below 55-60F. My preference is for Oxalic Acid Vapor. The equipment is a bit expensive to buy, but after that, every treatment costs a few cents, takes about 5 minutes to do, and you don’t have to open the hive and disturb the bees. OAV works at all temperatures, and if your hives are clustering and broodless, it works even better.

Thanks for the quick reply! Yes, I have built a Vivaldi board for ventilation; I’ve been waiting for the curing Tung Oil on it to dry, and I’ll be installing it shortly with burlap and some fondant.
As for robbing, I haven’t seen any since late summer, when it was going on really bad. After I installed a robber screen back in July and August, it stopped being a problem.
You’re probably right about varroa affecting them despite the treatment. This is what I feared when medicating them in weather less than 50F. I thought the internal hive temps are constantly above 90F? I was considering Oxalic Acid, but I didn’t want something that was too abrasive on the bees when they’re this weak. My beekeeping mentor has done ApiLifeVar in cold temps, with success. I guess every hive is different. I’ll ask her about oxalic acid. If I end up ordering it, and it comes late, is that the kind of bee med that works in the dead of winter effectively?

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It is if there is brood. If there is no brood, it may go lower. The studies I have looked at used outside temperatures when they were assessing the effectiveness of Thymol, so I guess that is more important for you to consider.

There is a very long, but extremely informative article about all treatment options here:

Oxalic Acid is not actually “abrasive” to bees, unlike Formic Acid, which can be very hard on them. It has been used in Europe and Canada for decades, and actually the Oxalic Acid “trickle” method is mostly done in about November. I don’t like the trickle, because you have to open the hive, but it works really well if your bees cluster.

I use the oxalic vapor year round. December, January, March, June, August, September, October and November are all months that I have used it. I have never seen piles of dead bees after a treatment. I have with MAQS (formic acid), although not in my hives because I don’t use Formic Acid. :blush:

Mann Lake have the Varrox vaporizer and mine came in less than a week. You can get the Oxalic from Home Depot (Savogran Wood Bleach is >99% pure Oxalic) and I ordered a jump starter from Amazon as a portable power supply.

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Wow, thanks for all the suggestions, and the pdf is very informative. If you don’t use the trickle method (I’ve heard it drips on bees and chills them if done in winter), how do you apply oxalic acid?

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With this:

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Thank you. This coming Sunday is supposed to be around 50F, so I’ll try oxalic acid then. I’ll keep you posted!

For vaporizing, you can do it any time the outside air temperature is above 40F, according to the manufacturer of the Varrox. :blush:

There is a video a short way down in this post:

Yesterday (Monday the 3rd) I applied oxalic acid. It was around 50-55F outside, there were a few foragers, and the bees were very chill in general. None flying around my face or anything. I could tell when I removed the inner cover that the bees were more or less grouped together on one side (the side where the sun hits the hive). They were in a very loose cluster because it was warmer yesterday than most days lately. After I applied the OA, I put a shim to put fondant for them, then put a vivaldi board for ventilation, and other winterizing components.

I read somewhere that if you don’t have a sticky board (which I don’t, my screened IPM bottom board came without one), you can cut a piece of cardboard to fit underneath the bottom board, and coat it with petroleum jelly (Vaseline) so that any varroa that fall off bees will stick to the board and I can count them. Have you done this before to see how many mites you killed with the OA treatment?

I hope that I have little to no brood so that this works effectively…of all the bees that I’m continuing to find dead in front of the entrance, none of them have deformed wings…that’s a good thing, right?

Yes, I do it every time. The board doesn’t need to be sticky after OAV, as the mites which fall are all dead, and can’t run away. You could put vaseline on it if you want, just don’t get the hot wand anywhere near it, as it could catch fire. I actually use the core flute slider under the Flow SBB. I just remove it and clean it off while I am vaporizing, then count mites exactly 24 hours later. If there are more than 25 on the board, I repeat the treatment at 5 day intervals. Here is a photo of my last drop - I will be treating again tomorrow:

Well, it is a bad thing if you see them, as it means that the infestation is very heavy, and the hive is at risk of dying within 6 months if you do nothing. But you are treating, so you are doing all the right things. :wink:

Good luck! :blush:

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Thanks Dawn! Sorry if I didn’t mention earlier, but I didn’t do the OA vapor method, because I didn’t have that kind of equipment on hand (and this is only one hive). I knew this had to be done fast, because we had only two 50-60 degree days before it dropped to the 30s again. I’m hoping that I can use the vapor method next time I treat with OA.
You said that you repeat the OA treatment at 5-day intervals; I’m guessing that’s with the vaporizing method, correct? I used the dribble method, carefully measuring out the ratio of sugar to water to oxalic acid. I dribbled 5mL of that solution on the bees of each seam of the hive. So, later when I go and check the sticky board and see more than 25 mites on it, should I repeat the dribble treatment? Or does that only apply to the vaporizing method?

1pm: I just went out there and removed the sticky board (this is 24 hours after OA dribble treatment). I counted 57 dead mites (sheesh!), one hive beetle, a few dead bees (they looked hollow…weird), and a lot of OA crystals. Is 57 dead mite count supposed to be good, as in “Wow, this is great, I killed a ton of mites” or as in “wow my bees have an overwhelming number of mites, they’re not gonna make it”? I’d prefer the former, but the advice of someone more experienced would probably be better! I wiped the sticky board clean and slid it back under the hive; I’m curious to see how many dead mites fall tomorrow…

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Correct. I have never used a dribble, as I am in California and it is too warm here for my bees to cluster.

One dribble should be sufficient. I have not heard of people repeating it. I would do a formal mite count in the Spring, and consider another treatment at that point.

By contrast, OAV gets repeated at 5 day intervals for several reasons.

  1. The dose is much lower. Only 2 grams for my double deep brood boxes.
  2. It is often done when there is sealed brood in the hive. OA vapor does not penetrate the cappings, so any mites under them will not get killed. In order to disrupt the mite life cycle, you have to repeat at 5-6 day intervals to knock the numbers down sufficiently.
  3. It is much less invasive than the dribble, so it is very easy to repeat. :wink:

The mite count I described is only for OAV treatment, not dribble. I wouldn’t worry too much about the count until Spring, other than curiosity. You have blasted the mites with a mega dose at the right time of year. That should be good enough. :blush:

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I just looked up a bit more on this.

Rusty is a good beekeeper and her advice is usually solid (except she doesn’t like Flow hives! :stuck_out_tongue_winking_eye: ), so I would follow her article advice and just treat once. She would probably say that your mite drop is high (in the comments section), but that doesn’t mean that you need to retreat, just that your treatment was needed:

Good article on storing leftover solution:

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Wow, thanks for all the info! Rusty was very helpful in the clear directions of the first webpage on how to mix the OA solution. The second solution is very informative. Because I had to dilute the OA crystals with a lot of sugar-water, I ended up with little less than a liter of the solution. I was wondering what to do with all that left over!

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So far, we’re looking good as far as the mite mortality. I’ve been keeping a chart for the past few days, and since Tuesday I’ve been counting the mites on the board:
Day 1 (24 hrs after treatment): 57 mites
Day 2: 89 mites
Day 3: 63 mites

The OA seems to be working well!

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The second link tells you how to store left over OA so all you need do is follow the instructions. The count of the mites sound like quite a big issue and hope it all goes well for your bees.

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December 17 Update:
Today had a high of 51F. I went outside to check on the mite count, and to see if the burlap on top of them is damp or not. Today is 14 days after the OA treatment. I pulled out the sticky board, and counted: wait for it…
EIGHT mites. No joke. Last week (day 7 after treatment) had 70 mites on the board. All these dead mites amount to 287 over the last two weeks. OA worked so much better than the other ApiLifeVar medication.
There continue to be many dead bees around the entrance, and I still can’t figure out why. I removed the burlap due to it being damp, and replaced it with new burlap. Before I did, however, I took a flashlight to shine into the hive real quick to see if they needed any more fondant. They were all in there, moving slowly and clustered together, and working on that fondant. I’m having a really good feeling about the bees making it this winter… :slight_smile:


That is an excellent result in mite control Kat, excellent hive management of the issue.

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