feeding bees

Why won’t my bees cap their syrup?

The syrup we feed bees in the fall is generally in the ratio of 2 parts sugar to 1 part water, either by weight or volume. That means the mixture is about 66% sugar and 34% water. But before the bees cap syrup (or honey) they dry it to roughly 17-18% water. Using round numbers, let’s call that 20%.

Now a solution of 80% sugar to 20% water is in the ratio of 4 to 1. So if you were making syrup this thick, you would have to put twice as much sugar into the water as you do for 2 to 1 syrup. That is really hard to do.

And remember we rounded up to 20%. If we wanted 18% moisture we would need 4.56 parts sugar to 1 part water, or 4.56 pounds of sugar to 1 pound of water. The 17% number requires 4.88 pounds of sugar to 1 pound of water—dangerously close to 5:1. As you can see, capped syrup (or honey) has very little water in it.

So the bees take their 2:1 syrup, store it in cells, and fan like crazy to drive off the extra water, of which there is a lot. Trouble is, as the ambient temperature gets colder in the fall, it becomes harder and harder to drive the water from the syrup. Not only is the liquid colder, but the cold air surrounding it can’t hold as much moisture as the warm air of summer. Add to that there are fewer bees doing the work. Everything slows down and capping takes forever if it happens at all.

Eventually, when the syrup itself reaches about 50° F (10° C), the bees give up and the syrup sits unattended in the feeder. You simply cannot feed liquid syrup to bees once the temperature of the syrup dips too low, which is why beekeepers use candy boards, fondant, or dry sugar for colonies that need a feed supplement in winter.




  • I’ve been feeding honey back to most of my hives instead of syrup. I learned from a Brushy Mountain video that the bees can convert 1 gallon (almost 4 litres) of thick syrup into a pound of stored syrup or fake honey.

    One of my hives took down six pounds of uncapped honey in about two days, or the equivalent of 23 litres of syrup.

    I know the bees still have to cap it, but if most of the raw honey I’ve fed them becomes stored honey without any extra work to evaporate it down to 17% water, feeding them honey seems much easier than mixing syrup and filling feeders, etc. And less work for the bees.

    Am I wrong about any of this?

    I’m tempted to empty a couple jars of honey for them to save them the trouble of evaporating sugar syrup.

    • Phillip,

      It’s always best to feed honey, if you have it. But that’s just the problem–we often have no honey of known origin, so we are stuck with feeding syrup. I always feed honey if I have the option.

      • “1 gallon of thick syrup into a pound of stored syrup or fake honey.”

        Is this correct? 1 Gallon of 2:1 Syrup has ~10lbs of sugar. How are the bees making ~1lb of honey?

  • I have read in several of your posts that it’s not advisable to feed the 2:1 syrup when the weather gets “too cold” because the bees won’t be able to evaporate the excess water. Can you give some temperature specifics on how cold is too cold?

    • Robert,

      The reason for not feeding syrup (any concentration) in cold weather is that honey bees refuse to drink it if the syrup (not the air) gets down to around 50 degrees F. In any case, most winter syrup is used as feed and is not generally stored. The honey bees have trouble driving the water out when the temperature is low because cold air doesn’t hold much moisture as warm air. If the bees store it at all, it may stay in a liquid form. Winter feed isn’t really intended for storing; it’s intended as feed.

  • Holy cow…now I’m really confused! We are first-year novices, and everything I’ve read suggested feeding 2:1 syrup in the fall, and that they would supplement their honey stores with this syrup. I assumed this meant that they would bring it down to the frames, de-humidify it and cap it. My original question was what is the threshold temperature below which they are unable to reduce water content, but your answer indicated that they won’t take syrup at all if it’s below 50 deg F and in any case won’t store it. Our local beekeeper group says in our area, the hives should have at least +/-70 lbs of honey for over-wintering. The bees only have around 30 lbs in the two deeps, most of which we moved to the upper deep. We have left a super on that has another 20-25 lbs. They never brought that honey down into the brood boxes. We are worried that we’re light – probably more like 50 lbs. What now: keep replenishing hard candy?

    • Robert,

      Yes, 2:1 syrup fed in the fall will be stored in the combs and used as winter stores. They will continue to store it until the syrup is too cold to drink, which is when the syrup (I’m repeating myself) reaches about 50 degrees F. Fall temperatures and humidity are not the same as winter temperatures and humidity, but it sounds like you’re thinking they are all the same.

      For this reason, if fall syrup is needed it should be fed in early fall before the temperature drops too much. You can usually tell by about August if you need to start supplemental feeding.

      There is no reason for the bees to bring stored syrup down lower, so that won’t happen. Instead the winter cluster moves up toward the food.

      About 70-90 pounds of stored food is about right for the colder areas of the US. If you don’t have that, you can keep them going on fondant or hard candy, but be sure not to let them run out.

  • We have a rather strange situation with a hive for which I seek your advice. We opened a hive that successfully overwintered in March to find a laying queen, eggs and larvae, but no capped brood. Food stores were low so we have been feeding and added frames with honey. At this point, the hive has adequate stores of honey and pollen; we have supplemented the hive three-four times with frames containing capped and open brood from other hives, but still the bees are not capping any newly laid eggs/larvae. The larvae appears normal. We have consulted with two other very experienced beekeepers, one of whom did a site visit, and neither has ever seen such a situation before.

    We also treated this hive with oxalic acid vaporizer in early December, and again with Api-Life-Var (as per application instructions) this spring. Since there has been no capped brood other than what I have added from other functioning hives (and these, too, have been treated similarly), we do not think there is a significant Varroa problem at this point.

    • Terri,

      You asked me this same question 10 days ago (May 17) in an email. As I explained then, eggs persist for three days. The eggs then hatch into larvae which persist for five-and-a-half days. After that, the cells are capped and the larvae pupate.

      In order to answer your question, I need to know what you are seeing after the larval period. You say the larva look normal, but they can’t exist for weeks on end in the larval form. So what is happening to them? Are they getting larger? Are they pupating without being capped? Are they dying? Are they getting removed from the cells by the workers? Are you finding larvae on the bottom board? Are they getting chewed? Are they turning yellow?

      You must notice something besides comb after comb of uncapped, over-aged larvae? If you pull some larvae out of the cells do they look normal? Do they have varroa attached? Do they smell odd? Do you have a photo?

    • Wilma,

      That is up to you and how much you want to feed them. They will probably empty it every day until the weather gets cold.

  • In preparing my 4 hives for winter I have installed 2 different types of candy boards. Two are the type that fit into the hive, and no cook sugar mixed with a small amount of water and pressed into a screen with vent areas on ends. The other two are a solid design made for cook and pour sugar mix.
    I used a candy thermometer and heated to 250°. I have heard that cooking sugar is bad for the bees. Should I remove those cooked candy boards? I’m doing my best to help my bees make it through the winter but I do not want to poison them with cooked candy boards.

    • Giselle,

      Beekeepers have been using cooked candy for decades. The feeling now is that you might have a higher mortality with cooked vs uncooked sugar, but the difference may be negligible. If it were me, I would go ahead and use the cooked boards since you already made them, but in the future I would stick to uncooked.

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