Bearding: what a curtain of bees on the front means

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What a beard actually is

A beard is bees hanging on the outside of the hive, usually under the entrance, on a warm day. It is a heat and space response. The colony has more bees than it has indoor work for, and more heat than it wants, so part of the workforce moves out and hangs on the front.

That costs the colony nothing. It drops the temperature inside and leaves room for the fanning bees to move air across the comb. A strong colony bearding on a warm evening is a strong colony.

No official body publishes on any of this. Take the description as ours.

The tells that it is ordinary bearding:

• It builds through the afternoon and clears overnight.
• The bees hang still and evenly spread, rather than milling about.
• Flying carries on as normal, with pollen going in.
• It is warm, or the hive is in full sun, or both.

Four out of four and you can stop worrying. That list is ours as well.

Bearding is not swarming

The two get confused because both put bees outside a hive. They stop looking alike quickly.

Swarming bees are in the air, loud, and moving as a mass. A beard is still. A swarm is gone in minutes. A beard hangs there for hours and walks back in at dusk.

The season is the other half of it. Swarming has a cause and a time of year, and a beard in late summer is very rarely it. If you are unsure, the question to answer is whether there are charged queen cells in the box, and queen cells: what you are looking at covers the reading. No cells, no swarm.

Bearding is not robbing either

Robbing also puts bees on the front of a hive, and it matters more in August and September, once the forage stops.

The difference is behaviour. Robbers fight at the entrance. They hover and probe the corners and the joins instead of using the front door, and there are dead bees and flakes of wax on the floor below.

A beard is calm, and the ground under it is clean. If it is robbing, reduce the entrance and take away whatever is drawing them in, which wasps at the hive covers properly. That comparison is ours rather than anybody’s official guidance.

Bearding while a thymol treatment is on

This is the question we get most in August, and the manufacturer answers it directly. Vita say bees often form a beard when it is too hot inside the hive, and that they sometimes do it when Apiguard first goes on in hot conditions, because the vapour builds quickly and they are not used to it. The behaviour is usually temporary, and it is rare for bees to abscond. 3

The authorised literature sets the weather window. Do not use the product when the maximum daily temperature expected during the treatment is lower than 15 °C, or when the temperature is above 40 °C, or when colony activity is very low. 1

There is no 30 °C limit on using it. The 30 °C figure that circulates is the storage instruction: do not store above 30 °C. 1 Keeping the tub out of a hot car is a different rule from keeping the tray off the hive.

What to do, in order:

• Check the timing. A beard that began the day the tray went on, in warm weather, is almost certainly the tray. That inference is ours.
• Leave the treatment on. The course is two 50 g applications two weeks apart, and the label asks you to leave the product in the colony until the container is empty. 1 Pulling it early for bearding alone wastes the course.
• Take it out for brood on the ground. If bees are removing uncapped brood from around the product, the label says remove the product from the colony. 1 Vita add: feed the colony, and check the dose matched the size of the hive. 3 Putting the varroa treatment on has the doses.
• Do not add product. Above 25 °C Vita halve it, to two 25 g doses one week apart. 3 Heat means less product, not more.
• Leave the entrance wide. Vita ask for an unrestricted entrance so the vapour can get out, and call good ventilation essential in these conditions. 3 That runs against the wasp advice for the same weeks, so watch a colony you would normally narrow.
• Shade the hive. Ours, and the cheapest thing on the list.

The open mesh floor is not the free win it looks. Vita advise closing it, or slipping the varroa tray in, while the treatment is on, so the vapour is not lost out of the bottom. They are equally clear that the entrance is never closed. 3 Air comes from the front and from shade, not from the floor.

Some colonies go quiet on eggs while the trays are on. Vita say thymol can sometimes stop the queen laying for a short period, that this does not happen often, and that she resumes as the odour goes, after about three weeks. 3 The authorised literature lists a slight reduction in young brood at high temperature as very rare, transient, and with no effect on how the colony develops. 1

Where the extra room actually goes

A beard reads as congestion, so the instinct is to add a box. Put it in the wrong place and the bees cannot use it.

An empty super above the crown board is not space for the colony. That box is there to house a feeder, and the crown board under it is closed apart from the feed hole. Feeders and the empty super covers why every other gap gets taped over.

Usable room sits under the crown board, above the brood frames. While an Apiguard treatment is on, it is already there. The label asks for at least 0.5 cm of free space between the top of the tray and the cover board, and Vita ask for a spacer or preferably an empty super on top of the brood chamber. 13

So the room has been made. Shade, an open entrance and a little patience are what is left.

Bearding after oxalic acid

Oxalic acid raises the question far less often, and the label explains why.

It is a broodless-colony product. The literature says use it in winter, or after manipulating the colony into a broodless state in summer, for example by caging the queen. 2 Sublimation is not recommended in summer. 2 Oxalic acid does not penetrate wax, and mites are thought to receive the acid by contact. 2 It works on the mites it touches, not on the bees.

It also does not sit in the box. Trickling and vaporising are each a single administration. 2 A thymol tray is on the hive for weeks. So a beard in the week you trickle is far more likely to be the weather, which is our reading rather than the label’s.

Expect some dead bees afterwards. Slight agitation during treatment, and an increased adult bee mortality rate after it, are listed as very common, meaning more than one colony in ten treated. 2 Judge the colony on flying and behaviour instead.

One instruction gets missed: avoid disturbance to the hives in the days after the treatment. 2 Look from the outside. Oxalic acid and the broodless window has the doses and the timing.

When it is worth a second look

• It does not clear at night, in cool weather, day after day. That is congestion or a problem inside, not heat.
• The colony is bearding and barely flying. Something is wrong in the box.
• Brood on the ground while a thymol treatment is on. That is the one sign the label tells you to act on: take the product out. 1
• Crawling bees, or dead bees in numbers, with no treatment to explain them.
• A beard in April or May on a box that is full. Read that as a swarm warning and go to preventing swarming.
• A treatment put on outside the temperature window on the label. 1 The window is not decoration.

When the simple rule breaks down

• Poly hives in full sun. They hold heat. Ours beard earlier and harder than the cedar ones, so shade them first.
• Solid floors. Less air, so more bearding. Not a fault in itself.
• A colony just reduced to one box. You took the space away, so they took it back outside.
• A feeder on, with the empty super round it. Bees working in that box can look like a beard from the front and are not one.
• Nucs. A small colony bearding is unusual. Look inside.
• A treatment week in a heatwave. Agitation is on both labels. 12 Read the colony over days rather than minutes.

The short version

• Bearding is heat and space management. It is normal, and usually a sign of strength. That reading is ours, not official guidance.
• It clears overnight. Swarming does not hang about for hours, and robbing is a fight rather than a curtain.
• With Apiguard on in hot weather, a beard is expected, usually temporary, and absconding is rare. 3
• Do not use Apiguard when the expected maximum daily temperature is below 15 °C or the temperature is above 40 °C. The 30 °C figure is storage. 1
• Do not pull the treatment for bearding. Do pull it if uncapped brood is being removed. 13
• In heat, less product rather than more, and leave the entrance open. 3
• Extra room goes under the crown board, not above it. During a treatment it is already there. 13
• After oxalic acid, a rise in adult mortality is very common, and the label asks you to leave the hive alone for the days that follow. 2
• Worry if it does not clear overnight, if flying has stopped, or if brood is on the ground. 1