Tag Archives: mating flight

Sphere of influence

How far do honey bees fly? An easy enough question, but one that is not straightforward to answer.

The flight range of the honeybee ...

The flight range of the honeybee …

Does the question mean any honey bee i.e. workers, drones or the queen? As individuals, or as a swarm?

Is the question how far can they fly? Or how far do they usually fly?

Why does any of this matter anyway?

Ladies first …

Workers

The first definitive experiments were done by John Eckert in the 1930’s. He located apiaries in the Wyoming badlands at increasing distances from natural or artificial forage 1. Essentially the bees were forced to fly over a moonscape of rocks, sand, sagebrush and cacti to reach an irrigated area with good forage. He then recorded weight gain or loss of the hives located at various distances from the forage.

Wyoming badlands

Wyoming badlands …

The original paper can be found online here (PDF). The experiments are thorough, explained well and make entertaining reading. They involved multiple colonies and were conducted in three successive years.

Surprisingly, Eckert showed that bees would forage up to 8.5 miles from the colony. This means they’d be making a round trip of at least 17 miles – and probably significantly more – to collect pollen and nectar.

However, although colonies situated within 2 miles of the nectar source gained weight, those situated more than 5 miles away lost weight during the experiments.

Gain or loss in hive weight ...

Gain or loss in hive weight …

Therefore, bees can forage over surprisingly long distances, but in doing so they use more resources than they gain.

John Eckert was the co-author (with Harry Laidlaw) of one of the classic books on queen rearing 2. His studies were probably the first thorough analysis of the abilities of worker bees to forage over long distances. Much more recently, Beekman and Ratnieks interpreted the waggle dance (PDF) of bees to calculate foraging distances to heather. In these studies, only 10% of the bees foraged ~6 miles from the hive, although over 50% travelled over 3.5 miles.

Queens

Queens don’t get to do a lot of flying. They go on one or two matings flights, perhaps preceded by shorter orientation flights, and they might swarm.

Heading for a DCA near you ...

Heading for a DCA near you …

I’ll deal with swarms separately. I’ll also assume that the orientation flights are no greater than those of workers (I don’t think there’s any data on queen orientation flight distance or duration) at no more than ~300 metres 3.

On mating flights the queen flies to a drone congregation area (DCA), mates with multiple drones and returns to the colony. DCA’s justify a complete post of their own, but are geographically-defined features, often used year after year.

There are a number of studies on queen mating range using genetically-distinguishable virgin queens and drones in isolated or semi-isolated locations. They ‘do what they say on the tin’, drone congregate there and wait for a virgin queen

In the 1930’s Klatt conducted studies using colonies on an isolated peninsula and observed successful mating at distances up to 6.3 miles

Studies in the 1950’s by Peer demonstrated that matings could occur between queens and drones originally separated by 10.1 miles 4. These studies showed an inverse relationship between distance and successful mating.

More recently, Jensen et al., produced data that was in agreement with this, with drone and queen colonies separated by 9.3 miles still successfully mating 5.

However, this more recent study also demonstrated that more than 50% of matings occurred within 1.5 miles and 90% occurring within 4.6 miles.

Just because they can, doesn’t mean they do 🙂

Drones … it takes 17 to tango …

Seventeen of course, because that’s one queen and an average of 16 drones 😉

There’s a problem with the queen mating flight distances listed above. Did the queen fly 9 miles and the drone fly just a short distance to the DCA?

Or vice versa?

10 miles ... you must be joking!

10 miles … you must be joking!

Or do they meet in the middle?

Do queens choose 6 to fly shorter distances because it minimises the risk of predation and because they are less muscle-bound and presumably less strong flyers than drones?

Alternatively, perhaps drones have evolved to visit local DCAs to maximise the time they have aloft without exhausting themselves flying miles first?

Or getting eaten.

It turns out that – at least in these long-distance liaisons – it’s the queen that probably flies further. Drones do prefer local DCAs 7 and most DCAs are located less than 3 miles from the ‘drone’ apiary 8.

Swarms

I’ve discussed the relocation of swarms recently. Perhaps surprisingly (at least in terms of forage competition), swarms prefer to relocate relatively near the originating hive. Metres rather than miles.

The sphere of influence

Effective foraging – in terms of honey production (or, for that matter, brood rearing) – occurs within 2-3 miles of the hive. This distance is also the furthest that drones usually fly to occupy DCAs for mating.

Queens can fly further, but it’s the law of diminishing returns. Literally. The vast majority of matings occur within 5 miles of the hive.

In fact, other than under exceptional circumstances, a radius of 5 miles from a colony probably represents its ‘sphere of influence’ … either things that can influence the colony, or that the colony can influence.

Why does this matter?

Worker flight distances are relevant if you want to know the nectar sources your bees are able to exploit, or the pollination services they can provide. In both cases, closer is better. It used to also be relevant in trying to track down the source of pesticide kills, though fortunately these are very much rarer these days.

Closer is better ...

Closer is better …

Workers not only fly to forage on plants and trees. They also fly to rob other colonies. I don’t think there are any studies on the distances over which robbing can occur, but I’ve followed bees the best part of a mile across fields from my apiary to find the source of the robbing 9.

All of these movements can also transport diseases about, either in the form of phoretic Varroa mites piggybacking and carrying a toxic viral payload, or as spores from the foulbroods.

Drone and queen flight distances are important if you’re interested in establishing isolated mating sites to maintain particular strains of bees. My friends in the Scottish Native Honey Bee Society have recently described their efforts to establish an isolated queen mating site in the Ochil Hills.

And I’m interested as I now have access to a site over 6 miles from the nearest honey bees in an area largely free of Varroa.

It’s not the Wyoming badlands, but it’s very remote 🙂


 

Keep Calm and Have Patience

Around this time of the season§ the discussion forums are awash with questions about virgin queens failing to emerge, or get out to mate, or return from mating flights, or start laying eggs, or any of a myriad of other possible things that can go wrong between a sealed queen cell and a nicely laying queen.

Or where to buy a new queen for a terminally queenless colony.

Followed a week later by a question about what to do with a recently purchased, and soon to be delivered, queen that is now surplus to requirement as – miraculously – a beautiful mated and laying queen is now obviously present and busy in the hive 😉

There she is ...

There she is …

Practice makes perfect

There’s good evidence from recent genetic studies that the honey bee (Apis mellifera) evolved about 300,000 years ago from Asian cavity-nesting bees. This was determined by analysing 140 bees sampled from around the world. The genetic differences between them (over 8.3 million in total) were identified and then – knowing the rate at which differences arise – it was possible to extrapolate backwards to define the approximate time the first honey bee (Eve?) evolved.

Early human ...

Early human …

For comparison, humans – modern man, Homo sapiens – have been around for about the same length of time.

Coincidence? Probably.

300,000 years is a long time when compared to the lifespan of a human, or a bee. However, it’s a mere blink of an eye in evolutionary terms. It also means that bees, and humans, are relatively recent arrivals when compared with fig wasps (34 million years), coelacanths (65 million years) or elephant sharks (420 million years).

Nevertheless, although bees might be evolutionary newcomers, they have been getting it right for about 300,000 years. Which means they’ve been superceding and swarming ever since modern man was recognisably modern man.

Which means they’re reasonably good at it … ‘it’ being reproduction, and more specifically getting the queen mated.

If they weren’t any good at it they’d be long gone by now.

Going by the book

The development of the queen takes 16 days from egg to eclosed (emerged) virgin. Three days as an egg, a further 6 days as a larva at which point the cell is sealed. Pupation then lasts for a further 7 days. The recently emerged queen needs to become sexually mature. This process takes a further 5 to 6 days before she goes on one (or more) matings flight(s). After mating she then returns to the hive and, after a further 2-3 days, starts laying eggs.

So, under optimal conditions, it takes a minimum of ~23-25 days to go from egg to mated and laying queen i.e. about three and a half weeks.

If a queen is removed from the hive, deliberately or by accident, there could be a new, mated laying queen present about three and a half weeks later.

There she goes ...

There she goes …

In fact, it’s possible the new queen could be mated and laying in less time than this. The queenless colony might start to rear young larvae as queens, so ‘saving’ a few days. It’s generally reckoned that larvae up to about three days old can be selected by the colony and reared as queens, though younger is better as they are better fed for longer.

Bees can’t read

However, things rarely go by the book. Although development time is pretty-much fixed at 16 days from newly laid egg to emerged virgin, there’s plenty of opportunity to lengthen (and rarely shorten, as outlined above) the time taken before the queen starts laying.

Chief amongst these is getting conditions suitable for queen mating. Typically this needs to be warm and settled weather. High teens centigrade, sunny and light winds between late morning and mid/late afternoon. If this doesn’t occur the queen stays put in the hive.

There’s also a time window within which successful mating must occur. This starts when the queen reaches sexual maturity (~5-6 days after emergence) and ends three to four weeks later (~26-33 days after emergence). A few days of poor weather during this period may well delay mating. Three weeks of lousy weather can be catastrophic – she may well turn out to be poorly mated or, if she doesn’t mate, a drone laying queen.

Depending on where you live, it’s rare to get three continuous weeks of terrible weather during the predominant swarming period (late April to late-July perhaps). However, it’s not uncommon to get a week or so of ‘unseasonable’ weather. In 2017, June was the wettest on record in Fife – precisely when I expected my virgins to be going out to mate.

Keep calm and Have Patience

Keep Calm ...

Keep Calm …

All this means is that you need patience when waiting for newly mated and laying queens in your colonies. In my experience it usually takes longer than it could, and it’s almost always longer than I want.

You should be able to calculate when the virgin queen will emerge to within a day or so of the colony becoming queenless. Better still, judge the development of queen cells and add 7 days to the date on which the cell become capped.

I usually check to make sure there’s a virgin queen in the hive. They’re small, skittish and often tricky to spot. They don’t get the same sort of attention from the workers as a mated queen gets. They can fly, and do if you disturb them too much. It’s reassuring to know there’s an emerged virgin present, but don’t keep checking. I try and check on the day after emergence. If you check too late and the weather is good there’s a chance you’ll interrupt her returning from a mating flight, with possibly disastrous consequences.

Then wait.

Observe the bees at the hive entrance and look for them returning laden with pollen. If you must inspect the colony (why?) do so early or late in the day. Don’t bother looking for the queen. Instead look for polished cells in the middle of the central frames … and eggs of course.

Dates from my diary

In June 2017 new queens should have emerged from my vertical splits on or shortly after the 2nd. Under optimal conditions I could hope these virgins would be mated and laying by the 12th at the latest. The splits were all set up on the same day. I didn’t check every hive for the presence of a virgin, and didn’t find one in every hive I checked, but I did find the expected vacated queen cell.

It then started raining. Lots. One of my apiaries flooded.

I had a quick look on the 12th in a couple of hives – no eggs. I checked again around the 22nd. The 18th had near-perfect weather for queen mating – sunny, 20+°C, light winds – and found mated, laying queens in a couple of boxes. But not in all of them. It wasn’t until the 27th that I found evidence that the latest queen was mated and laying well. She’d obviously started a day or so earlier as there were already eggs across two full frames.

All but two splits appears to have been successful – defined by presence of a laying queen. None were mated and laying anywhere near the minimal possible 9-10 days after emergence. One developed laying workers and I suspect the queen got lost on a mating flight quite early on. The second looks promising and I’ve not yet given up hope on this remaining colony.

I don’t keep records of the time it takes for new queens to get mated. However, from emergence (the date of which I usually do know) I wouldn’t be surprised if the average was a little over 21 days.

The shortest mating times I’ve seen occur in ideal weather conditions when using mini-nucs for queen rearing – under these circumstances ~11-12 days is not uncommon. But that’s a post for the future …

Keep Calm and Carry On


§ This was written in mid/late June in Fife, Scotland … about two weeks after the peak of the swarm season.

Wallberg  et al., A worldwide survey of genome sequence variation provides insight into the evolutionary history of the honeybee Apis mellifera. Nature Genetics, 2014; DOI: 10.1038/NG.3077

‡ Huber et al., New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens. Nature, 2017; DOI:10.1038/nature22336

∞ OK … formally, I know that supercedure might not be considered as ‘reproduction’.

∑ Though how it can be considered unseasonable when it’s not uncommon is a mystery 😉

∏ Of course, the true measure of success when rearing new queens is much more rigorous than this. They need to primarily lay fertilised worker eggs, have a tight laying pattern, mother well-behaved, calm bees that work well in the local environment, do not have a tendency to swarm, are frugal with winter stores and build up well in early Spring. And the rest …

Colophon

Keep Calm and Carry On was the text on a motivational poster produced in 1939 in the run up to World War II. Millions of copies were printed but few were ever displayed … in fact, many were pulped in 1940 to help overcome a serious paper shortage.

There’s an excellent account of the history and (many) compromises made during the design and preparation of the poster (almost 78 years to the day I’m writing this) on the Government history blog – highly recommended.

The poster was largely forgotten until 2000 when it was re-discovered. The rest, as they say, is history … it’s now ubiquitous, corrupted in a load of different ways and used on all sorts of novelty and decorative products.

You can even design your own …