A warm autumn in the apiary: loose reflections and real threats

I am writing this in October, and outside the window is weather that a decade ago would have been an abstraction: sun, a dozen-odd degrees above zero, bees flying as if it were May and coming back with pollen loads. Warm autumns have become the norm here, not the exception, and every year the same questions come back from beginners: if it is this warm, do I look into the colonies or not? Feed still, or is it too late? Or maybe just leave the bees in peace? Treat this text as loose reflections from the apiary about what a warm autumn does to a colony and what threats it brings, not as a rigid set of instructions.

I will say it straight away, because this is my stance after years: in this period I do not open the hive without need. It is not a hard rule, because sometimes you have to look inside to judge what is going on, and then you do it, better to react than to lose a colony. But I do not rummage in the nest for the sake of looking, because at this stage every needless opening does more harm than good. My standard move, if I do anything at all, is putting white candy on top, as insurance. Below I share what a warm autumn really does to a colony, what threats lie in wait for it, and what to avoid.

What a warm autumn does to a colony

Let us start with what is happening in the hive, because without that the rest is guesswork. In autumn key changes take place in the colony: the winter bee is raised, a long-lived generation meant to carry the colony through to spring, the queen gradually limits laying, and the drones are driven out of the hive still in late summer and early autumn, usually in August and September, so by October it is normally over for them. As the temperature drops, the bees form a cluster, in the centre of which they hold about twenty-five degrees, and up to thirty-five with brood. On warm days they still come out for cleansing flights.

A warm autumn stretches and disrupts all these processes. The queen, instead of calmly winding laying down, can lay much longer, sometimes into late autumn. On the face of it nice, because the colony looks alive and strong, but it comes at a price. First, keeping brood and staying active costs stores, so a colony in a warm autumn eats more than in a cold one, and what was meant to last the winter melts away faster. Second, a bee raised very late will wear out anyway before it is really needed in spring. There is also a greater risk of varroa reinvasion with the long flights and robbing, but that is a subject for a separate post.

From this comes a simple conclusion: a warm autumn is not a reason to rejoice that the colony is so lively, but a signal to watch the stores above all and not to get in the bees' way as they prepare for winter.

Should you look into the hives in warm weather

And here we come to my stance. In this period I no longer open nests or shift frames, because there is nothing to gain and plenty to lose. By now the bees have put their house in order: they have sealed the gaps with propolis, arranged the stores above and around the cluster, built the nest the way that suits them for winter. Every opening of the hive destroys those seals, breaks up the nest arrangement and chills the centre that the bees are keeping warm with such effort. After such an inspection the colony has to seal and rebuild from scratch what I have wrecked, spending on it energy and stores it does not have to spare in autumn.

The rule that the less we look in, the better, holds most strongly of all in autumn. The most important jobs, that is wintering on the right number of frames, making and ripening the stores and arranging the nest, should essentially be sorted before this period. I will say honestly, though, that you cannot hold the calendar to a ruler, because much depends on the forage. Late forage can stir things up a good deal: goldenrod or heather can draw a flow long into autumn and a strong colony still brings it in. So it is not that everything ends rigidly in August, rather that the closer to the real cold, the less there is left to do in the nest, and if someone badly neglected the stores, they will not make up much in late autumn. At this stage you mainly observe the colony, you do not take it apart.

That does not mean you leave the apiary to itself and vanish until spring. You can and should observe, just from the outside. Look at the entrance: whether there is a calm orientation flight on warm days, whether there are no clustering, clearly foreign bees at the entrance, which heralds robbing. Glance at the front wall of the hive and the landing board: brown, dysentery streaks, a heap of dead bees, or deformed, twisted individuals are signals that something bad is going on inside. Finally check whether the entrance is narrowed and protected against mice. All this tells you plenty about the colony's condition without opening the nest.

There is one more old, non-invasive way to assess the most important thing, that is the stores: lever the hive up at the back, or lift it slightly, and judge the weight by hand. Beekeepers call it the heft test, and after a few seasons you develop a feel for when a hive is decently heavy and when it is suspiciously light. A light hive in late autumn is a warning that the stores may not last to spring, and that is exactly when the candy on top comes into play, which I come to shortly. A heavy, well-stocked hive is better simply left in peace.

Varroa monitoring, or how I know it is time to act

There is one more thing you can check without taking the nest apart, and which says the most about the threat to the colony: the daily varroa mite drop. My floor is a solid one, with a groove into which you slide a sheet of paper or a thin board, ideally smeared with something sticky or greasy so the mites adhere. You leave the insert for a few days, then count the dead mites and divide by the number of days, and out comes the average drop per day, a real signal rather than a hunch. A mesh floor is a different construction, but the principle of counting the drop stays the same.

There is no point taking the thresholds apart to the last detail, it is enough to know roughly: in summer it is a few mites a day, and in autumn a drop of several, let alone a dozen or more a day, is already a sign that there is no point waiting. The exact thresholds and what to react with I have laid out in a separate post on varroa treatment. Here one thing matters: the insert lets you make the decision without opening the cluster, which fits perfectly with the autumn rule of as little rummaging in the nest as possible.

Feeding, or why not syrup but candy

The second great temptation of a warm autumn is feeding. Here you have to separate two things. The main winter stores, that is processed and capped feed, are made earlier, in summer and early autumn, with syrup or invert, while it is still warm enough for the bees to process and cap it. If you are reading this in late, warm autumn, that train has usually left. Giving syrup now misses the point, because with cooler nights the bees will not process it properly, and spilt, uncapped feed raises the humidity in the hive and can ferment.

That is why my standard move at this stage is putting white sugar candy on top of the nest. Candy is a solid feed that the bees take only when they really need it, dissolving it with the moisture from their own bodies and the hive. It forces nothing on the colony, does not raise humidity the way poured syrup does and does not require taking the nest apart. It is insurance: if the stores run short or the cluster moves away from them in the frost, the bees have emergency feed over their heads and will not starve. If they do not need it, the candy simply stays untouched.

In practice it is dead simple. Ready candy from the beekeeping shop comes in packs of a kilo or two, and you lay the slab on top of the nest, right over the cluster, so the bees can reach it moving upwards. The whole thing comes down to opening just the top of the hive, that is lifting the inner cover or crown board, and setting down the candy, without pulling out frames or taking the nest apart. It is a matter of a dozen seconds, not an inspection.

But there is one absolutely crucial condition: this candy must be clean, with no additives. Pure sugar and that is all. I explain why it is so important, because this is where beginners make dangerous mistakes.

First, no honey from an uncertain source. Honey of unknown origin can contain American foulbrood spores, and with that candy you would be introducing them straight into the nest. It is the simplest way to bring in a disease subject to official control. Second, and few think of this, no pollen or pollen substitutes in the candy for this period. Candy with added protein stimulates the queen to lay, and that is exactly what you do not want now. A colony stimulated to lay in late autumn means more brood, more food for varroa, greater use of stores and bees that wear themselves out rearing when they should be saving their strength for winter. Protein candy has its place, but in spring, to stimulate development, not in autumn. Third, drop all the herbal and other miracle additives. For winter the bees need clean energy, not experiments.

In short, white candy with no additives is quiet insurance that does not mess with the colony's plans. Candy with additives is asking for trouble.

A word on insulation

Since we are putting something on top, a quick word on insulation. At my place it stays on the crown board all year round and in my view it does the colonies good: it helps hold the warmth over the cluster and limits condensation under the crown board, that cold, dripping ceiling that does more harm than the frost itself. In a warm autumn it does not overheat the bees, because the colony regulates its temperature itself, it just matters that it is dry and breathable, not stewing. If you put down candy, it ends up right under that insulation. More on what to insulate with and how is in a separate post on hive insulation.

The threats of a warm autumn

A warm autumn is not just longer flights and pretty photos of bees on asters. It is also a time when several things threaten the colony at once, and it is worth keeping them in mind.

Robbing. When it is warm and forage is scarce, bees start looking around for someone else's honey. Weaker colonies fall prey to stronger ones, and the whole apiary can slip into a nervous, aggressive mood that feeds itself. The simplest defence is narrowed entrances, which a weak colony can guard, and not tempting the bees with spilt syrup or exposed honey near the hives. Clustering, clearly foreign bees at the entrance and fights on the landing board are a sign that robbing is already under way.

Wasps and hornets. A warm autumn prolongs the activity of wasps and hornets, and at this time of year they are especially persistent and hungry. They patrol the entrances, snatch individual bees and get at the stores, and the worst hit are weak colonies that have no one to guard the entrance. What helps most is a narrowed entrance and a strong colony that drives the intruders off itself. Traps for wasps and hornets help too, but that is something you set out from summer on, not something you dream up only in autumn. And make no mistake: killing a few wasps will not solve the problem, because the source is a nest somewhere nearby, so put your bets above all on defending the entrance and on strong colonies.

The Asian hornet on the horizon. It is worth knowing that the Asian hornet, Vespa velutina, is spreading across Europe, hunting at hive entrances and able to harass apiaries badly. It is already in Germany, the Czech Republic and Slovakia, so it is knocking on our door, though in Poland it has not been confirmed for now. It is smaller than our native European hornet, darker, with an orange band on the abdomen and yellow leg tips. If one day you think you are looking at it, do not destroy the nest on your own, just take a photo from a safe distance, note the place and time and report it to the proper services. For now it is a subject to watch, not to panic over.

Mice. Warmth in autumn lulls your vigilance, and it is precisely now that rodents start looking for a warm, dry corner for the winter, and a hive suits that perfectly. A mouse that gets inside destroys combs, eats the stores and the colony's peace, and the stench it leaves can spoil the nest for a long time. So before the first frosts come, narrow the entrances or fit mouse guards. It is one of those things easy to put off on a warm day and bitterly regret later.

What to actually do in a warm autumn

Pulling it into a practical list, in a warm autumn my actions look like this:

• I do not open nests without clear need. The bees have everything arranged and sealed, I do not wreck it for them.

• I put white sugar candy on top. Clean, no additives, as emergency stores. They take it if they need it.

• I observe from the outside. A calm orientation flight on warm days, movement at the entrance, no dysentery and no foreign bees in front of the hive.

• I assess the stores by hand. The heft test, that is a slight lift of the hive at the back, instead of opening the nest. A light hive is a signal, a heavy one I leave in peace.

• I monitor the drop on the insert. The daily varroa drop from the floor insert tells me whether I need to act, without opening the nest.

• I keep an eye on the entrances. Narrowed entrances and protection against mice, before the cold comes and the search for a warm corner begins. A narrowed entrance is also a defence against robbing, wasps and hornets.

• I do not feed syrup or shift frames. The main stores and nest arrangement were to be done earlier, now I leave it to the bees.

Curiosities and controversies

A warm autumn is not a gift but a challenge. Intuition suggests that the longer it stays warm, the better for the bees. In practice it is the opposite: prolonged activity and laying eat the stores, wear out the bees and extend the season for varroa. A mild but shorter autumn is often healthier for the colony than one dragging on for weeks in the warmth.

Less looking in, more trust. Among beginners there persists a belief that a good beekeeper is one who looks in often. In autumn it is exactly the other way round. A colony that is not broken open every few moments by an inspection holds its warmth and seals better, and goes into winter calmer. Sometimes the best thing you can do for the bees is leave them alone.

Candy the bees take themselves. What is interesting about sugar candy is that the bees take it as they need it. They will not touch dry candy by force, only the moisture from the hive and their own bodies dissolves the sugar enough for them to take it. That is why well-placed, clean candy will not harm, and in a crisis will save the colony from starvation.

The winter bee is a different model from the summer one. A summer worker lives a few weeks, while a winter bee lives a few months, because it is born with an enlarged fat body that acts as a store of protein and energy for the whole winter. That is why we care so much that in autumn it emerges healthy and unworn, not exhausted by late laying. More on what the fat body is and why it decides wintering I have written in a separate post.

The most common mistakes

Feeding syrup too late. Poured feed given in late, cold autumn will not be processed and capped, raises humidity and can ferment. The stores are made earlier.

Candy with additives. Honey from an uncertain source is a foulbrood risk, and pollen or protein substitutes stimulate unwanted autumn laying. For this period, only pure sugar.

Forgetting to protect against mice. Warmth lulls your vigilance, and rodents are looking for a warm corner right now. Narrowed, protected entrances are an autumn duty.

Sources and further reading

• Materials on the autumn changes in the bee colony (winter bee, limiting of laying, cluster formation, cleansing flights) and on the influence of warm autumns and winters on colonies. Basis for the section on what warm weather does to the colony.

• Lyson and beekeeping portals, materials on sugar candy and solid feeds for bees. The use of candy as a supplementary and emergency feed and the risks of additives.

• The posts "Good wintering", "Arranging the nest for winter" and "Hive insulation" on the Beehive Hub blog. Preparing the stores, nest and insulation before winter, which this text refers to.

• The post "The bee's fat body" on the Beehive Hub blog. The role of the fat body in the winter bee and its importance for wintering.

• Materials on the Asian hornet (Vespa velutina), incl. Lyson and veterinary and agricultural services. The spread of the species in Europe (Germany, the Czech Republic, Slovakia), the lack of confirmation in Poland, hunting at hive entrances and the rules for reporting. Basis for the section on wasps and hornets.

• Materials on varroa monitoring by the daily mite drop method (incl. infowet.pl, Pasieka24, beekeeping portals). The floor insert method and the rough daily drop thresholds through the season. Basis for the section on when you need to act.