11 May 2013

A Swarm ... of Honey Bees

Is this a swarm?
If you're reading this page because you have discovered what you think is a swarm of honey bees in a tree, on a post, a car bumper or the outside of a building, you need to be sure it is swarm of honey bees. Check first by doing an image search and/or visiting the BBKA site, which has several pictures of swarms.

Is this a colony of Honey Bees?
If you have bees living in a building, a tree or in the ground then they might not be honey bees.
  • Insects with yellow and black stripes and an almost hairless body, living in a papery-looking nest in a shed, an attic, or in a tree or hedge, are probably wasps or hornets (Vespa crabro - friendly giants).
  • If the bees you can see are large and very hairy, maybe thumbnail sized and living in a bird box or a hole in the ground, they are more likely to be bumble bees.
  • If there are only a few smallish bees, entering and leaving a pencil-sized entrance in a wall or a bank, they could be solitary bees - mason bees etc. (There are over 200 species of solitary bees in the British Isles).
  • If the bees are not bumble bees, and there are a lot of smallish (little fingernail sized) bees coming and going through a hole of about an inch diameter (2.5cm) in a tree, in brickwork, near a window frame, in a roof or a chimney and some of them (not all of them) are arriving at the nest entrance carrying something yellow or orange (pollen or propolis) on their back legs, they could be honey bees.
Bumble bees and solitary bees are unlikely to sting. They will build up small colonies during a season, but do not make large permanent nests. Towards the end of their season, which may be July or August, the colony raises a number of fertile queens. These are the individual bees that overwinter, on their own. These not-honey-bees are unlikely to return to the same nest site the following year.

If you are sure you have honey bees, and would like them collected or removed you can find contact details your nearest swarm collector via the BBKA site, and on Honey Bee Swarm Collectors UK.

Swarming is the honey bees' means of reproduction. Individual honey bees cannot go off and start a new colony on their own - they have to work together, have to stay together, and have to keep the queen healthy and safe from predators. Seeley calls a colony of bees a 'superorganism' - a single organism comprising many individuals, much the same principle as corals or sponges, with honeycomb being the framework of their home.

What is a swarm.
A swarm of honey bees contains a number of flying worker bees, drones, and a queen. She could be a newly-emerged, unmated, virgin queen or an older, mated queen.

There are various sizes of swarms. The largest is a 'Prime Swarm', and will include almost all the flying bees from a colony and the existing queen - maybe 30,000+ bees. A prime swarm can be big enough to fill a family-sized coolbox, whilst a later cast swarm might only be big enough to fill a coffee cup.

Swarming bees first fill themselves up with honey and then go - all at once, from their home colony. They fly some distance away and then land, clustering around the queen until they have chosen a new home.

What happens next
... to the swarm.
Swarming bees don't always plan ahead. The most important thing, at first, is just to go - to leave their or no-longer-suitable, overcrowded, home. It's only afterwards that they start looking for somewhere to live. Scout bees will search up to a mile in any direction for a new nesting site whilst the main body of the swarm will hang quietly (very quietly) from a tree, or anything else they can find. Their search could last anything from an hour or so to several days.

Their new home could be an out-of-use chimney capped with a nice terracotta pot that has bee-preferred entrances of about 2.5cm (a inch) in diameter. They will also choose cavities in old trees, beneath broken slates, behind weatherboarding, in stone walls and buildings - anywhere that is weatherproof, has an easily-defensible entrance, and a large enough space for a developing colony - Seeley's research suggests around 40 litres is optimum.

Once they've chosen their preferred site they will move in. They will take off from their temporary roost and sly in a straight line to their new home - in a bee line! They might make a lot of noise (think several Harleys for a Prime Swarm) while in the air - it's their wings - but once they land they will be very quiet because there's no sense in advertising the exact location of their new nest site. I have seen an good-sized prime swarm move into a chimney in a little more than ten minutes, but it will of course take longer for a swarm to pass through a single small hole into a tree cavity.

As soon as the new colony is in its' new home the wax-makers will begin to secrete wax plates, which will be collected by other workers that will chew and mould it to build comb. As soon as the first cells are completed a good, fertile, queen will start laying - this can be within hours. Whilst this is happening foragers will be searching for nectar sources - they only have the food they carried in their honey stomach (about the size of a pin head) so finding fresh nectar is urgent.

It will take only a couple of days for the new nest to be fully established, but will take much longer for the colony to build up a large enough store of food and a enough bees to over winter successfully.

What happens next ...
... in their original home.
The swarming bees have left behind a colony comprising mostly 'house bees' (those that have not yet taken their first orientation flights), brood in all stages of development, and at least one freshly capped queen cell - ensuring that a new queen will emerge within 8 days. They also leave behind all the food they can't carry in their stomachs, which means the 'home' colony has plenty of stored food.

After the new queen emerges (she is not born - no other bee gives birth to her) she will spend up to a week being fed and getting strong enough to fly, then a group of workers will take her on her first orientation flight.

Once she knows the location of her home a group of workers will take her for several mating flights - to drone congregation areas - where she will be inseminated by, hopefully for her and her colony, the healthiest, strongest and fastest drones in the area. Mating flights will continue until she has been mated by 15 - 20 drones. In good weather this could be just one or two flights, but if it is damp or wet and only a few drones are flying, she will need to make several flights which can take a week or more to complete - and each one carries the risk of being eaten by birds, such as swallows or swifts.

It's worth remembering that the workers control the queen's behaviour, guided by her pheromones - a poor queen, with low pheromone levels, will be replaced.

By the time the new queen is mated, if all goes according to plan, a lot of the brood laid by the old queen will have emerged (21 days from egg-laying to worker bee) and the previous house bees will have developed their foraging skills, so will be collecting stores. This mated queen will stay with, and within, the colony and will be committed to egg laying for the whole of her productive life. (Until she is either superseded or it is her turn to leave with a swarm.) To begin with her egg-laying may be erratic, with more than one egg per cell, but the workers will sort them out - either eating the spare eggs (protein) or moving them to unoccupied cells. Her freshly laid eggs will hatch in 3 days, new worker bees will start emerging about 21 days after laying.

The first queen to emerge from a group of several swarm cells will, almost always, kill all the other developing queens by stinging them through the walls of their cells - but sometimes she won't be allowed to. Sometimes the new virgin (unmated) queens will be taken from the hive by a small group of workers, sometimes this will continue with each new queen until there is only one left within the colony. These smaller swarms are called "Cast Swarms", and may be as small as a grapefruit or a coffee cup when seen clustering on a tree or bush, so could easily pass unnoticed - it would be rare for one of these tiny swarms to survive to the next season.

A colony that loses a prime swarm and several cast swarms will be significantly reduced in size, and may have problems building up sufficient numbers, and storing sufficient food, to survive a winter. This is the main reason why beekeepers make efforts to control swarming, and also why some will do their best to perpetuate the genes of their less-swarmy bees.

When does all this happen?
A swarm in May is worth a load of hay*,
A swarm in June is worth a silver spoon,
A swarm in July ain't worth a fly.

In a normal year a healthy colony will prepare to swarm as early as possible, with swarms being seen from April or May onwards - depending on local conditions. The earlier in the year that a swarm leaves, the longer the bees have to prepare for the next winter and so stand a greater chance of surviving into the following year, and forming more swarms - thus carrying their genes down the generations.

In nature, honey bees can only reproduce by swarming. In the apiary the beekeeper will split a colony to mimic swarming behaviour.

Swarms in July and later are likely to be small, more likely to contain unmated virgin queens. They are unlikely - without a beekeeper's help - to survive a winter, simply because there will not be enough bees to keep the colony warm, and there will not have been enough time for them to forage and store sufficient food to last until bud-burst the next Spring.

* Don't be fooled by visions of expensive silver cutlery. A 'load' of hay converted into cash will pay for more than one silver spoon, even in today's money.


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