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Bumble Bees

There have been quite a few posts around the gardening and beekeeping groups on Facebook over the last couple of weeks, where people are concerned at seeing dying bumble bees around lately, sometimes in large numbers. They are wondering whether the bees are starving and need to be fed, or whether they have been poisoned.

I’ve worked with honeybees for over a decade, but in the last couple of years I’ve really enjoyed getting to work with bumble bees too, raising several hundred colonies, so I thought I’d weigh in and hopefully put some minds to rest.

To make a long story short: don’t panic, there’s no bee-pocalypse going on. Bumble bee nests are a short lived entity, and right now.. late summer/early autumn.. the last of the bumble bee nests are dying off because they’ve reached the end of their life cycle and it is, quite simply, their time to die.

Please do not feed them – check out my previous post on why it’s a bad idea to feed bees for more info on that: https://www.facebook.com/…/a.423002691452…/707077053045555/… . It is always possible that someone may have found a bee or bees that have been poisoned, either inadvertently or deliberately, but the probability is that this is just their natural die off.

That’s it in a nutshell.
If you’d like a bit of a fuller explanation, read on. 😊
(Bit of a disclaimer – I’m generally talking about bombus terrestris, which is our most common bumble bee here. There are about three other species here in NZ, but they all follow similar enough life cycles to terrestris).

Ok, first things first – what’s the difference between honey bees and bumble bees?

Well, aside from the obvious visual differences…. Heaps!

Honey bees form enormous colonies with seasonal populations that range from maybe 10,000 bees in winter, through to 60,000 bees or more in summer. Barring disaster, they are a perennial colony that can occupy the same hive for generations, and years on end. In fact, some of our earliest hives are still going strong over a decade later, and led by great, great, great granddaughter queens of the original queen. It’s a massive and highly ordered society, with just one egg laying female and although we call her a ‘queen’, she is royal in name only – she’s more of an egg laying slave with the narrowest experience of the world, completely incapable of taking care of herself without her hive, or of starting a hive on her own.

A bumble bee nest is an entirely different thing, started by just one young mated queen after she emerges from solo hibernation in late winter, and the nest has a normal total lifespan of only a few months.

After emerging from hibernation, the young queen will forage for pollen and nectar to feed herself, while looking for a suitable hole in the ground – old mouse nests are ideal – to start her nest. Once she’s found a home, she’ll build a simple wax cup, smaller than a thimble, to store nectar in and she’ll lay her first egg in a small wax casing, about the size of a small dry lentil. She’ll leave a pinhead sized hole in the wax shell, through which she’ll feed the developing larvae. The wax casings grow as the larval bee does, from a lentil to a large pea sized cell, and then about three weeks after the egg was laid her first worker daughter will emerge.

All through this first stage, the queen has worked alone to raise her first daughters – heading out foraging for pollen and nectar every day as the weather allows, storing food, producing wax, incubating, feeding babies. No honey bee queen could do what this bumble bee queen has done – a honey bee queen never forages, never builds wax combs, never even feeds her young – she’s just there to lay the eggs.

It fascinated me when I first started working with the bumble bees and I was catching them in the wild while they were foraging for nectar. If I missed a bumble queen with my net, the reaction was completely different than if I took the same swing at a honey bee. The worker honey bee would fly off their flower, shrug, and go straight back to work as if I was completely irrelevant, or as if they had very little sense of self-preservation…. It actually took quite a bit of effort to annoy them enough to go away. A bumble queen, on the other hand, would fly off her flower, immediately go into a zig zag evasive flight pattern, and after a moment when she’d collected her thoughts, would often come and fly straight up to me, clearly indignant and intent on getting a good look at this annoying creature… and, just maybe, trying to give me a warning…. and then she would fly away completely, presumably not to return while I was still there.

I can’t describe it as anything less than an ‘intelligent’ response to a threat. The first time I saw it I had to giggle.. the second time I was hooked.

Anyways, I digress. 😊 Good at that, me.

So our bumble bee queen has raised her first, say, half dozen daughters, which could all emerge within a day or two of each other, and there may be another couple of dozen young bees incubating away. These first daughters will be physically small – it takes a lot of resources to feed young bees, and how well the queen has been able to forage and feed them will have a big influence here – they may be smaller than a house fly, or closer to a blue bottle fly in size if really well fed. In a fairly short time, these daughters will take over a lot of the house keeping jobs from their queen mother, and eventually they’ll take over the foraging outside the nest so she can stay home and concentrate on laying more eggs.

There’s a great photo of a bumble bee nest here: https://teara.govt.nz/en/photograph/11164/bumblebee-nest

With a workforce to support her, the queen can now lay many more eggs and the nest will grow dramatically, perhaps expanding to a couple of hundred bees in the next month or two. Each successive round of worker daughters tends to be a bit bigger than the last, having been raised by more sisters and better fed, and she will be able to live longer, forage further, and carry more food as a result.

This is about the time when we humans tend to start noticing that we have a bumble bee nest under our front door step, or in the insulation of a shed wall or in a dry compost heap. Foraging flights increase and a bee might leave or arrive at the nest entrance every minute or so. In New Zealand, this could be any time from about October onwards, but I usually get phone calls asking for bumble bee nests to be removed around December.

Here’s where it gets a bit wild. At some point, and the hard part with bumble bees is there is no particular rule for when or at what nest size this will happen… but, at some point, the queen will produce queen daughters. Physically larger and different from the worker daughter the queen has produced until that point, she will not stay home and tend the nest; she’ll fly out and find a drone – a male bumble bee – to mate with. She (and her sisters) will probably return home to the nest for a while, and the nest may continue to live together happily for some extended time.

But then, and, again, we don’t know exactly when or why, things turn to custard. The social nature of the nest starts to break down… workers will start to attack the old queen, try to lay eggs themselves, and generally start behaving like a bunch of lager louts after a home team loss.

Not pretty.

Eventually the nest will fall apart completely – the old queen and many of the workers and any drones will die. Young mated queens who have not already left home for good will fly out again, and may forage around a while, fattening themselves up and looking for a dry spot to hibernate until next spring.

Some surviving workers and drones will also fly out, foraging until they reach the end of their short lifespan, and these are quite probably the bees that people are noting around recently.

In fact, most of these nests have already died out by Christmas, so those that are still around by now may well be very large nests that might fill a shoebox and number perhaps 400 bees that have survived well beyond their time.

So that’s it for our bumble bees… a short, but impressive and important life cycle.

And at the end of next winter hundreds and thousands of young, already mated queen bumble bees will emerge from their hibernation chambers that they’re already sleeping in as I write, and start the whole wonderful cycle all over again.

(If you made it this far.. well done!.. and for the record, that girl in my hand is just sleeping, not dead 😊 )

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