Condensation: why insulation beats ventilation

I pulled the roof off a stack of wooden Langstroth nuc boxes this week and got soaked. A big swarm had moved into them a while back, I’d popped a metal roof on top and left them to it. Water everywhere. Puddles of it.

In August that costs you nothing. The bees were probably grateful for a drink, given how dry it’s been. Do the same thing in November and you’ll lose the colony.

So this week’s questions ran straight from that puddle into the jobs that actually matter right now. Getting the honey off, treating for varroa, and giving colonies enough space that they don’t swarm at the back end of the season.

What this episode covers

• Why condensation forms where it does, and where your insulation should go
• Taking the honey off early this year, and why that’s a health decision
• How many Apivar strips a colony actually needs
• Overwintering on double brood, then resetting to single brood in spring
• Getting the most colonies out of one strong hive next season

Damp does more damage than cold

A beehive makes huge amounts of moisture and huge amounts of heat. Warm air holds that moisture, so the humidity inside a hive is very high. All of it has to go somewhere, and it will condense on the least insulated surface you’ve given it.

On that nuc stack, the walls were wood and the roof was thin metal. Wood isn’t a proper insulator, but it beats metal easily. So I’d built the worst possible setup by accident. The coldest surface was the roof, directly above the cluster, and every bit of moisture in that box went up there and sat waiting to drop back down on the bees.

Get it the right way round and the problem solves itself. Insulation on top, crown board on, insulated roof on, and the mesh floor left open underneath. Now the roof is the warmest part of the hive, so moisture condenses on the side walls instead. Gravity takes it down and the open mesh lets it out.

This is why I keep recommending a poly rapid feeder. You can feed syrup, flip it over for fondant, and either way you’ve made the top of that hive better insulated than anything else on it. Even on a polyhive it helps.

If you’re overwintering in a poly nuc, do nothing clever. The insulation is already doing its job. Leave the mesh open, cover the top properly, and let the bees manage their own temperature and humidity.

Ventilation in winter isn’t about swapping stale air for fresh. It’s an exit route for water.

Get the honey off now, then treat

For most people the season is done. If you’re in Scotland you might have a few weeks left. Everywhere else, the bees are starting to eat into what they’ve stored.

I’m taking supers off and going in with Apivar on the 1st of August, then leaving it for eight weeks. Don’t drift into late August or early September with this. The whole point of harvesting early is to treat early, so the bees go into winter carrying less virus.

People on social media took that the wrong way and said I was only interested in the honey. I’m not. The honey comes off so the treatment can go on. The focus is the health of the colony.

On extracting, don’t be too precious about cappings. If the honey is ripe you can extract it. A fully capped frame is obviously good to go, and in the 14-Day Beekeeper we use roughly 80% capped as the rule. What people forget is that those 100% frames sit below optimum moisture, so they balance out the wetter ones in the extractor and the settling tank. Shake the frame, test the moisture, and aim for something around 16 to 18% in the bucket. Plenty of frames you’d normally reject can go in the mix.

And no, I wouldn’t bother with a blast of oxalic acid before the Apivar goes in. Whatever system you use, run two different approaches against the mites. Apivar does the work now. Save your single oxalic hit for a broodless period, which I’m aiming to trigger with the cold around the winter solstice. Done then it can take out up to 95% of the mites. Done now, when most mites are still under cappings, you might knock off 20%.

One strip per five frames of brood

Apivar dosing confuses people because they count boxes. Count frames of brood instead.

Seven or eight frames of brood gets two strips. Twelve frames gets three. Round up if you’re between, spread the strips evenly, and put them where the brood actually is. Single brood, double brood, empty frames, none of that changes the sum.

Late season nucs are easier still. There’s no honey crop to protect, so you can treat the day you make them up. Three frames of brood, two frames of stores, a good shake of bees and then another for luck. Put a strip slap bang in the middle of the brood nest. Take them to a different apiary if you can, keep the entrance small, and they’ll come out of winter in good shape.

Add a brood box, not a problem

One viewer asked what to do about space once the supers come off, and it’s the right question this year. The old advice of letting the bees compress down into a single brood box works in late August. In early August it doesn’t. You’ll have too many bees in one box, bearding at the entrance, hard to defend against wasps, and thinking about swarming.

So take the supers off and put a second brood box on top. Trickle feed if they need it, rather than pumping them full of syrup. They’ve still got foraging left in them.

Over winter the bees migrate up, leaving brood at the bottom and stores above. Come spring the bottom box is empty and you lift it away, which puts you back on single brood at exactly the right moment. That’s also the setup you need for a Demaree later on, and it means you never have to fiddle about with artificial swarms.

If you’re sat there post Demaree with a brood box, a stack of supers and another brood box on top, harvest the supers and stack what’s left as brood box at the bottom, stores on top. Two boxes, one floor, repeatable all season.

Squeeze more colonies out of your best hive

If you want numbers rather than honey, the Demaree is the wrong tool. It gives you enormous colonies, it eats resources, and they can still swarm on you.

Build up hard and early instead. Get a wintered colony onto double brood, feed 1:1 syrup, and let them turn most of it into brood. You might come back to 16 frames of brood by late April or early May with a prolific Buckfast queen. That’s the moment the brood nest stops expanding, and that’s the moment to split.

One frame of brood, one frame of stores, wait eight days, knock down the emergency cells, put a mated queen in, keep feeding. Sixteen frames becomes sixteen colonies, and most will be ready to split again later in the season. I stopped at 20 because it was too much work at that time of year, not because it stopped working.

One warning. Don’t feed a split you’ve left in the same apiary. The foragers fly back to the parent hive and carry the message that there’s a free buffet next door, and they’ll strip the new nuc bare. Leave it a few days and the nurse bees will hold the fort. Better still, move it to another apiary and you can feed from day one.

Spare frames of capped honey in the freezer are worth more next spring than they are as winter feed. Thaw them for splits and an eight frame colony gives you eight nucs instead of four.

A beehive creates huge amounts of moisture and huge amounts of heat, which means the air can hold the moisture.

What to do next

This week, in this order:

1. Walk your apiary and work out which part of each hive is least insulated. If it isn’t the roof, fix that before autumn.
2. Get the supers off, count frames of brood, and put the right number of Apivar strips in.
3. Add a second brood box to anything that will be crowded once the supers go, then trickle feed.
4. Making nucs now? Three frames of brood, two of stores, a generous shake of bees, strip in the middle, and move them to a different apiary.
5. Put spare capped frames in the freezer and label them for next spring’s splits.
6. If your bees are bad tempered, plan to requeen with calmer stock rather than putting up with another season of it. I was told for years that local bees were the only option, and it nearly finished me twice.