Category Archives: Miscellaneous

Biological control with Varroa

Synopsis : Honey bees were eradicated on Santa Cruz Island following the introduction of Varroa. This provides some useful lessons for beekeepers on the importance of controlling Varroa.

Introduction

Honey bees are not native to North America. They were first introduced in March 1622 at Jamestown, Virginia. The bees did well and spread west, following the settlers. They finally arrived on the west coast, in Santa Clara, California, 231 years later in 1853. Of a dozen hives ordered by Christopher Shelton, a Santa Clara botanist and rancher, only one survived the journey from New York via Panama.

Shelton barely had a chance to enjoy his bees 1 as he was unfortunately killed when the steamboat Jenny Lind exploded in mid-April 1853.

Explosion on the steamboat Jenny Lind near San Francisco, California

His bees survived 2 and three hives derived from the original stock were auctioned for $110 each. This was over 20 times the price of hives on the east coast at that time and equivalent to over $4200 today 3.

Californian Channel Islands map

Bees were in demand and they continued to spread – both as feral swarms and as farmers established apiaries to help pollination and for honey production. Having reached the California coast they were then spread to the nearby islands. Bees were transported to Santa Cruz, the largest of the eight Channel Islands near Los Angeles, in the 1880’s. They flourished, but did not spread to the other Channel Islands.

Field station, nature reserves, pigs and bees

Santa Cruz Island is 250 square kilometres in area and lies ~35 km south of Santa Barbara. It is one of the four Northern Channel islands. There is a long central valley lying approximately east-west and the rocky mountainous land reaches 740 m. It has a marine temperate climate; the average low and high temperatures are 9°C and 21°C respectively and it receives about 0.5 m of rain a year. It is a good environment for bees.

From the 1880’s to 1960’s Santa Cruz Island was farmed – primarily for wine and wool, and from the 1940’s for cattle – but, after period of university geology field trips and the establishment of a field station on the island, in 1973 it became part of the University of California’s Natural Reserve System (UC NRS).

In the late 1970’s the Stanton family sold their ranching business on the island to The Nature Conservancy who subsequently bought additional land on the eastern end of the island.

Santa Cruz Island is now jointly owned by The Nature Conservancy, National Parks Service, UC NRS and the Santa Cruz Island Foundation and much of the island is used for scientific research and education.

But what about the bees?

Good question.

As a nature reserve and research station, the presence of non-native species causes a potential problem. Why go to all the expense of managing a remote island research centre if all the same species are present as on the mainland?

The Nature Conservancy therefore initiated a programme of eradicating non-native species. It took 14 months to eliminate the feral pigs, using a combination of trapping, helicopter-based shooting and the release of sterilised radio-tagged pigs to locate the stragglers 4.

But getting rid of the bees took a bit longer …

Save the bees, or not

Why get rid of the bees? Surely they weren’t doing any harm?

The introduction of any non-native species upsets the balance (if there’s ever balance) in the ecosystem. The introduced species competes directly or indirectly with those native to the area and can lead to local extinctions.

Jonathan Rosen has described 5 how honey bee swarms, through occupying tree cavities previously used for nesting, probably played a major role in the extinction of the Carolina parakeet.

Pining for the fjords … a stuffed Carolina parakeet (nailed to its perch)

Competition between honey bees and native pollinators has been well studied. It is not always detrimental, but it certainly can be. Furthermore, it is probably more likely to be detrimental in a small, isolated, island ecosystem. For example, studies showed that the presence of honey bees dramatically reduced visitation of native pollinator to manzanita blossoms on Santa Cruz Island.

As part of the larger programme of non-native plant and animal eradication on Santa Cruz Island plans were drawn up in the late 1980’s to eliminate European honey bees. The expected benefits were to:

  • eliminate competition with native bee species (and presumably other non-bee pollinators, though these rarely get a mention 🙁 )
  • reduce pollination of weed species (some of which were also non-native to Santa Cruz Island)
  • facilitate recovery of native plant species that were reliant on native bee pollination
  • provide a ‘field laboratory’ free from ‘exotic’ honey bees in which comparative studies of native pollinators would be possible

Killer bees

After the plans to eradicate Apis mellifera were approved an additional potential benefit became apparent.

There were increasing concerns about the spread of Africanised honey bees which had recently reached Santa Barbara County. Although there was reasonably compelling evidence that swarms could not cross from the mainland (e.g. none of the other Northern Channel Islands had been colonised by bees) there were concerns that the Santa Ana winds might help blow drones from the mainland.

Had these drones arrived they might mate with the non-native but nevertheless local queens resulting in the spread of the dominant genes for defensiveness and absconding. The resulting swarmy, aggressive Africanised bees would cause problems for visitors and scientists working on the island (as they have for visitors to Joshua Tree National Park).

Aerial view of Santa Cruz Island

Although the introgression of African honey bee genes was used as further justification for the eradication it’s not clear whether drones could actually cross 30-40 km of open sea 6.

As an aside, there’s a current project – the amusingly named Game of Drones – running on the Isles of Scilly investigating whether drones can cross the sea between St Agnes, Tresco, Bryher, St Mary’s and St Martin’s. These are, at most, 11 km apart (northern most tip of St Martin’s to most southerly point of St Agnes) but the individual islands are only separated by 1-2 km. I would be surprised if drones could not cross that distance (at least with a strong following wind).

Killing bees

Adrian Wenner and colleagues set about exterminating the honey bees on Santa Cruz Island (Wenner et al., 2009). The process started in 1988 and ended in 2007, and was divided into four phases:

  1. 1988-1993 – location and elimination of feral colonies
  2. 1994-1997 – biological control and colony demise
  3. 1998-2004 – monitoring residual honey bee activity
  4. 2005-2007 – confirmation of the absence of honey bees

None of this is ’beekeeping’ – actually it’s the exact opposite – so I don’t intend to dwell in much detail on the work that was conducted. However, the ’94-’97 phase includes some sobering lessons for beekeepers which are worth discussing.

By the end of phase 1 the team had identified the existence (if not the location) of at least 200 colonies and eliminated 153 of them.

Remember, none of these were managed colonies in hives. They were all feral colonies occupying natural cavities in trees or rocks etc. Each colony was found using painstaking bee lining techniques similar to those described in Thomas Seeley’s book Following the Wild Bees.

Once located, nests were destroyed with methyl chloroform and the cavity sealed to prevent it being reoccupied.

Some colonies could not be accessed; in these cases acephate-laced sucrose-honey syrup baits were used. This organophosphate has delayed toxicity for bees, allowing foragers to return to the colony which in due course dies. This approach had been partially successful in eliminating Africanised bees on the mainland (Williams et al., 1989), but baits needed to be be monitored to avoid killing the other insects they attracted.

The scientists also deployed swarm traps (aka bait hives) and destroyed any swarms that moved in.

Together these interventions reduced honey bee numbers significantly – as monitored by regular observations at pollen- or nectar-rich plants – but did not eradicate them.

Let there be mite

Heavy rains in January ’93 washed out roads on Santa Cruz Island, thereby severely limiting travel around the island. In addition, the previous removal of cattle had resulted in the near-uncontrolled growth of fennel which now formed dense, impenetrable thickets.

Bee lining became impossible and the scientists had to invent more devious strategies to eliminate the residual feral colonies.

The approach they chose involved the introduction of Varroa.

Varroa was first detected in the USA in 1987 (in Florida) and became widespread over the next 5-8 years. Up until 1994 the honey bees on Santa Cruz Island were free of the ectoparasitic mite.

It was likely that they would have remained that way … there was no beekeeping on Santa Cruz Island and the location was too remote for bees to cross from the mainland (see above).

Varroa was already known to have a devastating impact on the health of honey bee colonies (Kraus and Page, 1995). It was also known that, other than its native host Apis cerana (the Eastern honey bee), Varroa did not parasitise other bee or wasp species (Kevan et al., 1991).

These two facts – host specificity and damage inflicted – suggested that Varroa could be used for biological control (‘biocontrol’) on Santa Cruz Island.

Biological control

Biological control or biocontrol is a method of controlling pests using natural mechanisms such as predation or parasitism.

The pest could be any living thing – from animals to bacterial plant diseases – present where it’s unwanted.

On Santa Cruz Island the pest was the honey bee.

In other studies (covered in a previous post entitled More from the fungi 7 ) biocontrol of Varroa has been investigated.

Control of the pest involves the introduction or application of a biological control agent. The key requirements of the latter have already been highlighted – specificity and damage.

Biological control works well when the specificity is high and the damage is therefore tightly targeted. It can be an abject failure – or worse, it can damage the ecosystem – if the specificity is low and/or the damage is widespread.

The cane toad was introduced to Australia to control infestations of greenback cane beetle (a pest of sugar cane). Cane toads were introduced in 1935 and rapidly spread. Unfortunately, cane toads can’t jump very high and so singularly failed to control the greenback cane beetle which tends to 8 stay high up the cane stems.

Female cane toad (not jumping)

But it gets worse; cane toads have a very catholic diet and so outcompeted other amphibians. They introduced foreign diseases to the native frogs and toads and – because of the poisons secreted from their skin – harmed or killed predators that attempted to eat them.

Oops.

Vertebrates are usually poor biological control agents as they tend to be generalist feeders i.e. no specificity.

But Varroa is specific and so the damage it causes is focused. The likelihood of ecosystem damage was considered low and so the mite was introduced to the island.

Introduction of Varroa

In late 1993 Adrian Wenner caught 85 foraging bees and, to each one, added a single Varroa mite. The bees were then released and presumably flew back to their colonies … taking the hitchhiking mite with them.

Adult mites – the dark red ones you see littering the Varroa tray after you treat with Apivar – are mated females.

Due to their incestuous lifestyle a single mite is sufficient to initiate a new infestation.

The mated adult female mite parasitises a honey bee pupa and produces a series of young; the first is male, the remainder are female. You’re probably reading this before the 9 pm watershed so I’ll leave it to your lurid imagination to work out what happens next (or you can read all the sordid details in Know your enemy).

The presence of honey bees – determined by successful swarm trapping or field observation at likely sites – was then regularly monitored over the next four years.

Swarm numbers remained largely unchanged until 1996 and then dramatically decreased.

Numbers of new swarms on Santa Cruz Island 1991 – 2005. Varroa introduction indicated.

It’s worth noting that during ’94-’96 over 70 swarms were found in natural sites or bait hives. There must have been a significant number of established colonies in 1993 to produce this number of swarms.

But, from 1997 it all stopped … only a single swarm was subsequently found, in a natural cavity in 2002.

Monitoring and confirmation of eradication

From 1998 to 2004 the scientists continued to actively monitor the island for honey bees, focusing on 19 areas rich in natural forage. Although honey bees were found – in decreasing numbers – there were too few to attempt bee lining to locate their colonies.

At the sites being monitored, bees were detected 9, 7, 4, 2 and 1 times respectively in the 5 years from 2000 to 2004. After that, despite continued monitoring, no more honey bees were detected.

The final phase of the project (’05-’07) confirmed the absence of honey bees on Santa Cruz Island.

Whilst, as a scientist, I’m a firm believer that ’absence of evidence does not mean evidence of absence’, as a beekeeper I’m well aware that if there are no scout bees, no swarms and no foragers (when I search in likely places) then there are no honey bee colonies.

Lessons for beekeepers

I wouldn’t have recounted this sorry tale – at least from a beekeeping perspective – unless I thought there were some useful lessons for beekeepers.

There are (at least) three.

The first relates to Varroa resistance, the second to Varroa transmission in the environment and the last to ‘safe’ levels of Varroa. All require some ‘arm waving guesstimates’ 9, but have a good grounding in other scientific studies.

Varroa resistance

There wasn’t any.

At a very conservative estimate there were at least 20 colonies remaining on Santa Cruz Island in 1995. I say ‘conservative’ because that assumes each colony generated two swarms that season (see graph above). In studies of other natural colonies only about 75% swarm annually, meaning the actual number of colonies could have been over 50.

The numbers – 20 or 50 – matter as they’re both much higher than the number of colonies most beekeepers manage (which, based upon BBKA quoted statistics, is about 5).

Whether it was 20 or 50, they were all eliminated following the introduction of 85 mites. Colonies did not become resistant to Varroa.

This all took a few years, but – inferring from the swarm numbers above – the vast majority of colonies were killed in just two years, 1994 and 1995. This timing would fit with numerous other studies of colony demise due to mites.

Wenner estimates that only 3 colonies survived until 2001.

Leaving small numbers of colonies 10 untreated with an expectation that resistance – or even tolerance (which is both more likely and not necessarily beneficial) – will arise is a futile exercise.

I’ve discussed this before … it’s a numbers game, and a handful of colonies isn’t enough.

Varroa spread

Wenner doesn’t elaborate on where the foragers were captured before he added the mites. If I was going to attempt this I’d have chosen several sites around the island to ensure as many feral colonies as possible acquired mites … let us assume that’s what he did.

However, with 85 mites piggybacking on returning workers, and somewhere between (my guesstimated) 20 to 50 colonies, I think it’s highly likely that at least some colonies received none of this ’founding’ mite population.

Yet almost all the colonies died within two years, and those that did not subsequently died with no further intervention from the scientists. We don’t know what killed off the last surviving colonies but — and I know I’m sticking my neck out here – I bet it was the mites.

This is compelling evidence for the spread of Varroa throughout the island environment, a process that occurs due to the activities of drifting and robbing.

If a neighbouring apiary to yours has mites some will end up in your hives … unless you are separated by several kilometres 11.

The transmission of mites in the environment is a very good reason to practice coordinated Varroa control.

One mite is all it takes

But, just as I’ve argued that some colonies may have received none of the founding mites, I’m equally sure that others will have acquired very small numbers of mites, perhaps just one.

And one mite is all it takes.

Without exceptional beekeeping skills, resistance in the bee population or rational Varroa control 12 there is no safe level of mites in a colony.

The more you prevent mites entering the colony in the first place, and the more of those that are present you eradicate, the better it is for your bees.

Here endeth the lesson 😉


Note

It’s worth noting that island populations do offer opportunities for the development of Varroa resistant (or tolerant) traits … if you start with enough colonies. Fries et al., (2006) describes the characteristics of the 13 surviving colonies on Gotland after leaving about 180 colonies untreated for several years. I’ve mentioned this previously and will return to it again to cover some related recent studies.

References

Fries, I., Imdorf, A. and Rosenkranz, P. (2006) ‘Survival of mite infested (Varroa destructor) honey bee (Apis mellifera) colonies in a Nordic climate’, Apidologie, 37(5), pp. 564–570. Available at: https://doi.org/10.1051/apido:2006031.

Kevan, P.G., Laverty, T.M. and Denmark, H.A. (1990) ‘Association of Varroa Jacobsoni with Organisms other than Honeybees and Implications for its Dispersal’, Bee World, 71(3), pp. 119–121. Available at: https://doi.org/10.1080/0005772X.1990.11099048.

Kraus, B. and Page, R.E. (1995) ‘Effect of Varroa jacobsoni (Mesostigmata: Varroidae) on feral Apis mellifera (Hymenoptera: Apidae) in California’, Environmental Entomology, 24(6), pp. 1473–1480. Available at: https://doi.org/10.1093/ee/24.6.1473.

Wenner, A.M., Thorp, R.W., and Barthell, J.F. (2009) ‘Biological control and eradication of feral honey bee colonies on Santa Cruz Island, California: A summary’, Proceedings of the 7th California Islands Symposium, pp. 327–335. Available as a PDF.

Williams, J.L., Danka, R.G. and Rinderer, T.E. (1989) ‘Baiting system for selective abatement of undesirable honey bees’, Apidologie, 20(2), pp. 175–179. Available at: https://doi.org/10.1051/apido:19890208.

 

Mellow fruitfulness

Synopsis : Final colony inspections and some thoughts on Apivar-contaminated supers, clearing dried supers, feeding fondant and John Keats’ beekeeping.

Introduction

The title of today’s post comes from the first line of the poem ’To Autumn’ by John Keats:

Season of mists and mellow fruitfulness

The poem was written just over 200 years ago and was the last major work by Keats (1795-1821) before he died of tuberculosis. Although it wasn’t received enthusiastically at the time, To Autumn is now one of the most highly regarded English poems.

The poem praises autumn, using the typically sensuous imagery of the Romantic poets, and describes the abundance of the season and the harvest as it transitions to winter.

That’s as maybe … the last few lines of the first verse raises some doubts about Keats’ beekeeping skills:

And still more, later flowers for the bees,
Until they think warm days will never cease,
 For summer has o’er-brimm’d their clammy cells.

It’s certainly true that there are late summer flowers that the bees can forage on 1. However, he’s probably mistaken in suggesting that the bees think in any sense that involves an appreciation of the future.

And what’s all this about clammy cells?

If there’s damp in the hive in late summer then it certainly doesn’t bode well for the winter ahead.

Clammy is now used mean damp; like vapour, perspiration or mist. The word was first used in this context in the mid-17th Century.

‘Clammy’ honey

But Keats is using an earlier meaning of ’clammy’ … in this case ’soft, moist and sticky; viscous, tenacious, adhesive’, which dates back to the late 14th-Century.

And anyone who has recently completed the honey harvest will be well aware of how apt that definition is 😉 … so maybe Keats was a beekeeper (with a broad vocabulary).

And gathering swallows twitter in the skies

That’s the last line of ’To Autumn’ (don’t worry … you’ve not inadvertently accessed the Poetry Please website). The swallows are gathering and, like most summer migrants, already moving south. Skeins of pink-footed geese have started arriving from Iceland and Greenland.

Skein of geese over Fife

My beekeeping over the last fortnight has been accompanied by the incessant, plaintive mewing of buzzards. These nest near my apiaries and the calling birds are almost certainly the young from this season.

A few nights ago, while hosing the extractor out in the bee-free-but-midge-filled late evening, I was serenaded by tawny owls as the adults evicted their young from the breeding territory in preparation for next season.

These are all signs, together with the early morning mists, that summer is slipping away and the autumn is gently arriving.

Morning mist clearing over the loch

The beekeeping season is effectively over and all that remains is preparing the colonies for winter.

Supers

All the supers were off by the 22nd of August. There was still a little bit of nectar being taken in but the majority was ripe and ready. As it turns out there was fresh nectar in all the colonies when I checked on the 10th of September, but in such small amounts – no more than half a frame – that it wouldn’t have been worth waiting for.

At some point you have to say … enough!

Or, this year, more than enough 🙂 .

Most of the honey was extracted by the end of August. It was a bonanza season with a very good spring, and an outstanding summer, crop. By some distance the best year I’ve had since returning to Scotland in 2015.

Of course, that also meant that there were more supers to extract and return and store for the winter ahead.

Lots of lifting, lots of extracting and lots of buckets … and in due course, lots of jarring.

Storing supers wet or dry?

In response to some recent questions on storing supers wet or dry I tested ‘drying’ some.

I’ve stored supers wet for several seasons. I think the bees ‘like’ the heady smell of honey when they are added back to the hives for the spring nectar flow. The supers store well and I’ve not had any problems with wax moth.

However, this year I have over two full carloads of supers, so – not having a trailer or a Toyota Hilux 2 – I have to make multiple trips back to put them in storage 3. These trips were a few days apart.

I added a stack of wet supers to a few hives on the 1st of September and cleared them on the 9th. All these supers were added over an empty super (being used as an eke to accommodate a half block of fondant – see below) topped with a crownboard with a small hole in it (no more than 2.5 cm in diameter, usually less).

Converting wet supers to dry supers – note the crownboard with a small central hole

When I removed the supers on the 10th they had been pretty well cleaned out by the bees. In one case the bottom super had a very small amount of fresh nectar in it.

So, 7-8 days should be sufficient for a strong colony to clean out 3-4 supers and it appears as though you can do it at the same time as feeding fondant … result 🙂 .

Feeding fondant

I only feed my colonies Baker’s fondant. I add this on the same day I remove the honey-laden supers. I’ve discussed fondant extensively here before and don’t intend to rehash the case for its use again.

Oh well, if you insist 😉 .

I can feed a colony in less than two minutes; unpacking the block, slicing it in half and placing it face down over a queen excluder (with an empty super as an eke) takes almost as much time to write as it does to do.

Take care with sharp knives … much easier with a slightly warm block of fondant

But speed isn’t the only advantage; I don’t need to purchase or store any special feeders (an Ashforth feeder costs £66 and will sit unused for 49 weeks of the year). I’ve also not risked slopping syrup about and so have avoided encouraging robbing bees or wasps.

I buy the fondant through my association. We paid £13 a block this year (up from about £11 last year). That’s more expensive than making or buying syrup (though not by much) and I don’t need to have buckets or whatever people use to store, transport and distribute syrup. Fondant has a long shelf life so I buy a quarter of a ton at a time and store what I don’t use.

All gone! 12.5 kg of fondant added on 22/8/22 and photographed on 9/9/22

And, contrary to what the naysayers claim, the bees take it down and store it very well.

What’s the biggest problem I’ve had using fondant?

The grief I get when I forget to return the breadknife I stole from the kitchen … 😉 .

Apivar-contaminated honey and supers

Last season I had to treat a colony with Apivar before the supers came off. This was one of our research colonies and we had to minimise mite levels before harvesting brood.

I’ve had a couple of questions recently on what to do with supers exposed to Apivar … this is what I’ve done/will do.

Apivar

The Apivar instructions state something like ’do not use when supers are present’ … I don’t have a set of instructions to check the precise wording (and can’t be bothered to search the labyrinthine VMD database).

Of course, you’re free to use Apivar whenever you want.

What those instructions mean is that honey collected if Apivar is in the hive will be ’tainted’ and must not be used for human consumption.

But, it’s OK for the bees 🙂 .

So, I didn’t extract my Apivar-exposed supers but instead I stored them – clearly labelled – protected from wasps, bees and mice.

This August, after removing the honey supers I added fondant to the colonies. In addition, I added an Apivar-exposed super underneath the very strongest colonies – between the floor and the lower brood box.

I’ll leave this super throughout the winter. The bees will either use the honey in situ or will move it up adjacent to the cluster.

In spring – if I get there early enough – the super will be empty.

If I’m late they may already be rearing brood in it 🙁 … not in itself a problem, other than it means I’m flirting with a ridiculous ’double brood and a half’.

Which, of course, is why I added it to the strongest double brood colonies. It’s very unlikely the queen will have laid up two complete boxes (above the nadired super) before I conduct the first inspection.

But what to do with the now-empty-but-Apivar-exposed supers?

It’s not clear from my interpretation of the Apivar instructions (that I currently can’t find) whether empty supers previously exposed to Apivar can be reused.

WARNING … my reading might be wrong. It states Apivar isn’t to be used when honey supers are on but, by inference, you can use and reuse brood frames that have been exposed to Apivar.

Could you extract honey from brood frames that have previously (i.e. distant, not immediate, past) been Apivar-exposed?

Some beekeepers might do this 4.

It’s at this point that some common sense it needed.

Just because re-using the miticide-exposed supers is not specifically outlawed 5 is it a good idea?

I don’t think it is.

Once the bees have emptied those supers I’ll melt the wax out and add fresh foundation before reusing them.

My justification goes something like this:

  • Although amitraz 6 isn’t wax-soluble a formamidine breakdown product of the miticide is. I have assumed that this contaminates the wax in the super.
  • I want to produce the highest quality honey. Of course this means great tasting. It also means things like wings, legs, dog hairs and miticides are excluded. I filter the honey to remove the bee bits, I don’t allow the puppies in the extracting room and I do not reuse supers exposed to miticides.
  • During a strong nectar flow bees draw fresh comb ‘for fun’. They’re desperate to have somewhere to store the stuff, so they’ll draw out comb in a new super very quickly. Yes, drawn comb is precious, but it’s also easy to replace.

Final inspections

I conducted final inspections of all my colonies in Fife last weekend 7.

For many of these colonies this was the first time they’d been opened since late July. By then most had had swarm control, many had been requeened and all were busy piling in the summer nectar.

Why disturb them?

The queen had space to lay, they weren’t likely to think about swarming again 8 and they were strong and healthy.

Midsummer inspections are hard work … lots of supers to lift.

If there’s no need then why do it?

Of course, some colonies were still busy requeening, or were being united or had some other reason that did necessitate a proper inspection … I don’t just abandon them 😉 .

I don’t just abandon them … introducing a queen to a nucleus colony

But now the supers were off it was important to check that the colonies were in a suitable state to go into the winter.

I take a lot of care over these final inspections as I want to be sure that the colony has the very best chance of surviving the winter. 

I check for overt disease, the amount of brood in all stages (BIAS; so determining if they are queenright) and the level of stores.

And, while I’m at it, I also try and avoid crushing the queen 🙁 .

Queenright?

I don’t have to see the queen. In fact, in most hives it’s almost impossible to see the queen because the box is packed with bees. If there are eggs present then the queen is present 9.

But, there might not be a whole lot of eggs to find.

Firstly, the queen is rapidly slowing down her egg laying rate. She’s not producing anything like 1500-2000 eggs per day by early autumn.

A National brood frame has ~3000 cells per side. If you find eggs equivalent in area to one side of a brood frame she’s laying at ~1000/day. By now it’s likely to be much less. At 500 eggs/day you can expect to find no more than half a frame of eggs in the hive.

Remember the steady-state 3:5:13 (or easier 1:2:4) ratio of eggs to larvae to pupae? 10

Several of my colonies had about half a frame of eggs but significantly more than four times that amount of sealed brood … clear evidence that the laying rate is slowing dramatically.

The shrinking brood nest – note the capped stores and a little space to lay in the centre of the frame

Secondly, the colony is rapidly filling the box with stores, so reducing the space she has to lay. They’re busy backfilling brood cells with nectar.

Look and ye shall find …

So I focus carefully on finding eggs. I gently blow onto the centre of the frames to move the bees aside and search for eggs.

In a couple of hives I was so focused on finding eggs that – as I prepared to return the frame to the colony – I only then saw the queen ambling around on the frame. D’oh!

Some colonies had only 3-4 frames of BIAS, others had lots more though guesstimating the precise area of brood is tricky because of the amount of backfilling taking place.

I still need to check my notes to determine whether it’s the younger queens that are still laying most eggs … I’d not be surprised.

Stores

Boxes are now heavy but not full. All received (at least) half a block of fondant in late August and more last weekend. There’s also a bit of late nectar. The initial half block was almost finished in a week.

Once the bag is empty I simply peel it away from the queen excluder. If you’re doing this, leave the surrounding super in place. It acts as a ‘funnel’ to keep the thousands of displaced bees in the hive rather than down your boots and all over the floor.

Although the bees were flying well, the bees in and around the super were pretty lethargic. I’ve seen this before and am not concerned. I don’t know whether these are bees gorged with stores, having a kip or perhaps young bees that don’t know their way about yet. However, it does mean that any bees dropped while removing the bag tend to wander aimlessly around on the ground.

I’d prefer they were in the hive, out of the way of my size 10’s.

If you look at many of the frames in the hive they will be partially or completely filled with stores. The outer frames are likely to be capped already. 

An outer frame of capped stores

These frames of stores are heavy. There’s no need to look through the entire box. I simply judge the weight of each frame and inspect any that are lighter than a full frame of stores.

Closer to the brood nest you’ll probably find a frame or two stuffed, wall-to-wall, with pollen. Again, a good sign of a healthy hive with the provisions it needs to rear the winter bees and make it to spring.

Disease

The only sign of disease I saw was a small amount of chalkbrood in one or two colonies. This is a perennial situation (it’s not really a problem) with some of my bees. Quite a few of my stocks have some (or a lot of) native Apis mellifera mellifera genes and these often have a bit of chalkbrood.

I also look for signs of overt deformed wing virus (DWV) damage to recently emerged workers. This is the most likely time of the year to see it as mite levels have been building all season and brood levels are decreasing fast. Therefore, developing brood is more likely to become infested and consequently develop symptoms.

Fortunately I didn’t see any signs of DWV damage and the initial impression following the first week or so of miticide treatment is that mite levels are very low this season. I’ll return to this topic once I’ve had a chance to do some proper counts after treating for at least 8-10 weeks (I use Apivar and, since my colonies all have medium to good levels of brood, the strips need to be present for more than the minimum recommended 6 weeks).

Closing up

Although these were the last hive inspections, they weren’t the last time I’ll be rummaging about in the brood box.

At some point during the period of miticide treatment I’ll reposition the strips (adjacent to the ever-shrinking brood nest) having scraped them to maximise their effectiveness.

Apivar scratch and sniff repositioning studies

However, all that will happen in a month or so when I can be reasonably sure the weather will be a lot less benign. Far better to get the inspections out of the way now, just in case.

So, having added the additional fondant (typically half a block) I closed the hives, strapped them up securely and let them get on with making their preparations for the coming winter.

Goodbye and thanks for the memories

There’s a poignancy about the last hive inspections of the season.

The weather was lovely, the colonies were strong and flying well, and the bees were wonderfully placid. It’s been a great season for honey, disease levels are low to negligible and queen rearing has gone well 11.

But it’s all over so soon 🙁 .

Hive #5 (pictured somewhere above … with the empty bag of fondant) was from a swarm control nuc made up on the last day of May (i.e. a 2021 queen). It was promoted to a full hive in mid-June. At the same time, while the hive they came from (#28) was requeening I’d taken more than 20 kg of spring honey from it. The requeening of #28 took longer than expected as the first was almost immediately superseded. Nevertheless, the two hives also produced almost 4 full supers (conservatively at least 40 kg) of summer honey.

Good times 🙂 .

My notes – for once – are comprehensive. Over the long, dark months ahead I’ll be able to sift through them to try and understand better 12 what went wrong.

That’s because – despite what I said in the opening paragraph of this section – there were inevitably any number of minor calamities and a couple of major snafu’s.

Or ’learning opportunities’ as I prefer to call them.

Last light over Rum and Eigg … not a bad view when visiting an out apiary

But that’s all for the future.

For the moment I have a sore back and aching fingers from extracting for days and the memory of a near-perfect final day of proper beekeeping.

It’s probably time I started building some frames 🙁


 

Making a beeline

Synopsis : Honey bees use a range of navigation skills including path integration – to shorten return flights – combined with map-like spatial memories to relocate the hive.

Introduction

Regular readers will be aware that I’m interested in the origins of words. The Oxford English Dictionary (OED) is a fantastic source of information and produces a free Word of the Day email 1. This includes both the meaning and etymology of one word each day.

Since the complete dictionary includes over 600,000 words it will take a few years to collate the 20 volumes that comprise the entire dictionary 2.

At the beginning of this week the word of the day was beeline.

The word beeline of course means:

A straight line or course, such as a bee follows in returning to its hive after having collected a full load of nectar; (occasionally) the course taken by a bee.

The word originated in the US almost 200 years ago. It was first recorded in the American Quarterly Review in June 1828. Anyone who has read Tom Seeley’s Following the Wild Bees will appreciate the context in which the word beeline was used:

The bee-hunter..encloses them [sc. bees] in a tube, and letting one fly, marks its course, by a pocket compass. Departing to some distance, at right angles to the bee-line just ascertained, he liberates another, observes its course, and thus determines the position of the hive, which lies in the angle made by the intersection of the bee-lines.

Beelining is the art of finding feral or wild colonies by following the returning flight of bees. The book has a companion website with some interesting videos if you’d like to know more.

Find and tell

Beelining ‘works’ because bees fly in a straight line back to the nest 3.

The basics of beelining

Assume the blue flowers above are nectar-rich and favoured by the bees. You capture a couple of bees feeding on the blue flowers and give them some additional syrup so that they are replete and need to return to the colony to unload.

When you release the bees at ‘A’ they fly at a particular bearing back to the colony. However, if you instead release them at ‘B’ they fly at a different compass bearing back to the colony.4  .

How did the bees find the nectar-rich blue flowers in the first place?

Perhaps they observed another worker in the colony performing the waggle dance which informed them of the angle (from the sun) and distance to the blue flowers?

Alternatively, they might have just been searching around and chanced upon the blue flowers … they didn’t know they were there in the first place.

If they found the blue flowers by interpreting the waggle dance then you should be thinking how the waggle dancing bee found the blue flowers.

Alternatively, if they found the blue flowers by chance then you should be wondering how they will communicate their location to other foragers in the colony.

Transient nectar sources

Nectar sources are transient. They yield at particular times of the year … and of the day. The nectar may be dependent on recent rainfall or a variety of other environmental conditions.

All this means is that foragers may have to search widely to find a good source of nectar. If the source is really good – ample sugar-rich nectar and with lots of flowers producing it – then it’s important that the forager that found it tells her half-sisters how to also quickly find the same source.

Foraging and finding

On the left the blue flowers have been yielding for days. The workers fly there in a straight line and return along the same path. Newly orientated workers observe the returning foragers waggle dancing and follow the same route to quickly and efficiently exploit the source.

But all good things come to an end …

On the right is what happens when blue flowers stop yielding. The foragers that arrive at the blue flowers find slim pickings and start casting about looking for a better source of nectar. They first find the marginally better yellow flowers, then the similar (but far from outstanding) purple flowers … so they keep looking.

And eventually, they find the red flowers. Lots of nectar and lots of flowers. They load up and return directly to the colony (black dotted line).

There are two striking things about this return flight. The first is that it does not follow (in reverse) the route by which they reached the red flowers. The second is that when these returning foragers perform the waggle dance they ‘instruct’ the observing bees to fly in the direction of the red dotted line … rather than to the blue, then yellow, then purple and then red flowers.

Path integration

The foragers who find the red flowers perform a process termed path integration to return:

Path integration is the process by which an animal, when moving away from a start point, often its nest, cumulatively sums its path, generating an internal vector that specifies the line from the animal’s current position back to the start point, however circuitous the outward trip (Collet, 2019).

This is a skill I singularly lack when trying to relocate my vehicle in the multi-storey car park.

Path integration is seen in other insects … Drosophila fruit flies can do it (over a range of centimetres), walking ants can do it over a range of hundreds of metres, and honey bees can do it over at least 5 kilometres (and probably more).

Path integration requires two pieces of information – the direction and the distance of travel.

Path integration – individual parts of the flight are in different directions and of different lengths

Clearly, the very existence of the waggle dance provides compelling evidence that bees are aware of both. The dancing forager reports the angle (relative to the sun) of the nectar source and the distance at that angle that must be covered before the nectar source is located.

But for path integration, not only must the angle and distances be determined, they must also be cumulatively summed.

Neurophysiology and evolutionary conservation

Detailed neurophysiological experiments – recording the firing of individual neurones in the bee’s brain – have identified that these events occur in a region called the central complex (CX).

Two types of neurones are involved; the first is a set of polarised-light-based compass neurones and the second are optic-flow-based speed neurones. The former use celestial cues to create a visual compass. The latter provide a visual odometer (Stone et al., 2017).

Together – and there are additional integrator cells that link these functions – this relatively simple 5 neuronal circuitry allows path integration, enabling the bee to return ‘home’ directly after a convoluted outward flight.

Many of these studies were conducted on the nocturnal sweat bee Megalopta genalis. This forages at night when polarised skylight provides the directional cues in its rainforest habitat.

Importantly, similar neuronal organisation is found in the CX’s of locusts, some butterflies and dung beetles. The visual odometer neurones were analysed in Megalopta genalis, but are physically and likely functionally similar to structures found in Bombus terrestris (a bumble bee).

You may have noticed that none of these studies used our favourite, Apis mellifera, the honey bee.

The evolution of termites, ants, wasps and bees

Nevertheless, there’s every reason to think that honey bee path integration involves very similar neuronal activity. Megalopta (belonging to the family Halictidae) and Bombus (a member of the Apidae family) are very distantly related and evolved from a common ancestor over 100 million years ago (Cardinal and Danforth, 2011). It’s therefore likely that all bees derived from this common ancestor – including honey bees – share similar neuronal activity underpinning their path integration ability.

Food vectors

Before considering another point about honey bee flight I wanted to to briefly mention features of the outbound trip back to the high quality food source (the red dotted line in diagram above). This is termed the food vector and is essentially the reverse of the path integrated return flight back to the colony i.e. the same length, but pointing in the opposite direction.

The waggle dance communicates this food vector to nest mates of the successful returning forager.

But what happens if bees are displaced when starting, or while following this food vector?

For example, if a huge gust of wind blew them off course by tens or hundreds of metres, or an evil eager scientist captured them as they left the hive and transported them in a dark box across a couple of fields and then released them?

Where do displaced foragers go?

Do the bees fly a corrected route to the food source (the blue dotted arrow), or do they continue flying the same vector (angle and distance – the green dotted arrow) they would have done when they left the hive?

I’m not sure this exact experiment has been done with bees (but see below), but it has been done with ants (Cataglyphis fortis). In these studies the ’displaced’ ants did alter their direction of travel (Collett et al., 1999). The food vector is more than just an angle and distance, it also points to a position relative to the nest. The redirection exhibited by the ants was not perfect, but it clearly showed they were able to integrate the path to a location other than the nest after displacement.

Gusts of wind are not the same as eager scientists

However, back to the bees.

The gust of wind and eager scientist are not equivalent. Bees cope with gusts of wind every day. It always amazes me how well bees cope on windy days.

When blown off course they will get lots of visual cues – not least changes in optic flow and their angle to the sun – both of which should be readily corrected. If they didn’t then foragers would be lost in droves on windy days … or fail to find the food source.

In contrast, the eager scientist took care to place the bees in a darkened box, thereby immediately removing visual cues such as the angle of the sun and the optic flow.

In the studies conducted with the ants the scientists made sure the ants could see the sky but not the surrounding landscape (they trained them in open topped channels). This is because ants can also use landmarks in the surrounding landscape for orientation 6.

And bees can do the same, which is the final sub-topic for this post on bee flight and orientation.

The map-like spatial memory of bees

Path integration is both useful and necessary. It means that foragers can return – fully laden – with minimum delay to the hive. They can therefore tell other foragers (via waggle dancing) promptly, and – in the case of elite foragers – they can set off again on another trip.

By reducing the distance flown – by integrating the path – they save not only time but ‘fuel’ as well i.e. path integration allows bees to maximise the nectar returned at the end of the foraging trip.

But, if all flights were a combination of random searches and path-integrated returns, why do bees go on orientation flights?

Orientation flights are short range (10’s to 100’s of metres) flights around the hive. These are taken by workers around 3 weeks after emergence as they transition form hive bees to foragers. They are also taken by older foragers if the hive is moved.

The very existence of orientation flights is compelling evidence that honey bees also use learned environmental landmarks for route finding, or at least for mapping the area around the hive to aid efficient return trips.

What evidence is there that these landmarks are used for this purpose?

Harmonic radar tracking of displaced foragers

I’ve previously discussed the use of short range harmonic radar to track bees ‘tagged’ with a small transponder. The key point is that it allows relatively accurate mapping of the entire flight of a bee up to 900 metres away. The resolution is, at best, about 3 metres.

Menzel and colleagues (Menzel et al., 2004) tracked the flights of three types of ‘displaced’ foragers:

  • SF-bees trained to a stationary feeder a few hundred metres from the hive; these have ‘route memory’ and have traversed the route from the hive to the feeder multiple times
  • VF-bees trained to a regularly moved feeder within 10 metres of the hive; these bees have no route memory
  • R-bees which were recruited by a waggle dancing forager and have only secondhand route information of the position of the feeder i.e. they have never made the trip themselves

These are not trivial experiments. To ensure the environment was as uniform as possible they conducted the experiments in a large, flat mown field approximately 800 metres square. There was no forage within the field other than the experimental feeders. The field was surrounded on all sides by uniform coniferous woodland with insufficient variation in elevation (<1.5°) above the horizontal to provide any visual clues to the bees.

The field itself was not uniform. There were differences due to different mowing times and soil conditions. In addition, the scientists erected a number of radar-transparent coloured tents around the hive to provide additional landmarks.

Common features of flight paths determined by harmonic radar studies

Bees were allowed to orientate to the new hive position and then SF- and VF-bees were collected at a feeder and R-bees were captured as they left the observation hive (having ‘watched’ a waggle dance). The bees were fitted with a transponder, released some distance away from the feeder or the hive and then tracked by radar.

SF- and VF-bees were stuffed full of syrup and so – although they could fly for a long time – were motivated to return to the hive to unload their cargo. R-bees, whilst ‘primed’ to seek the feeder, had limited range and so would have to return to the hive to refuel.

Return flights of SF-, VF- and R-bees show some common features.

The SF- and R-bees exhibited three broadly conserved flight patterns during their return trip to the hive:

  1. A fast (20 m/s) straight line flight in the direction they would have taken back to the hive (for the SF-bees) or out to the feeder (for the R-bees). The length of this part of the flight was approximately the distance between the hive and the feeder.
  2. A slow (13 m/s) curved search flight.
  3. A fast homing flight back to the hive.

The VF-bees only exhibited the slow curved search flight and the final fast homing flight. This was unsurprising as they had never learned (or been told) to follow the route between the hive and distant feeder.

Food vectors and von Frisch

We therefore have the answer to the question I posed earlier (in the Food vector section above). A bee displaced when about to embark for the first time on a trip to a distant feeder – learnt from following a waggle dance – initially flies at the angle and to the approximate distance they would have taken from the hive (stage 1 of the flight).

Remember, unlike the ants, these foragers are ‘in the dark’ while being displaced, so have no visual clues about the displacement.

This is a really nice result and supports the contention made by von Frisch that the waggle dance communicates only distance and direction (relative to the sun) information, rather than positional information (von Frisch, 1967) 7.

Homeward bound

After a period of slow curved flights the returning forager switches to a direct, fast homing flight. These started at positions – starred in the figure above – from which the bee could not see the hive (based upon distance and the known resolution of honey bee vision).

Homing flights of displaced SF-, VF- and R-bees (A, B, C respectively). H indicates the position of the hive.

Individual bees were randomly displaced around the study field. The homing flights were in a straight(ish) line and bees approached the hive from a range of different points of the compass. This argues strongly against the bees following a particular feature on the ground that led them back to the hive.

Instead, the authors argue that, since all the bees exhibit these direct homing flights, it must be based upon previous exploratory memory i.e. from orientation flights.

The tents were not critical landmarks. If they were moved some distance away the bees still returned using the same three flight phases (in the case of SF- and R-bees) and with similar navigational performance. Clearly there was sufficient information in the ground structure alone (mowing patterns, soil differences) acquired during the orientation flights.

In support of this, some of the harmonic radar data showed bees flying along boundaries between mown areas (in a similar way to homing pigeons follow rivers or motorways; Guilford and Biro, 2014.).

These experiments indicate that during orientation flights the bee develops a local spatial memory of landmarks that provide a ‘memory map’. This enables the bee to return to the nest once it recognises some of these familiar landmarks.

Repeated displacement flights of the same bee further indicated that the landmarks recognised (whatever they were) could be approached from different angles.

Final inspections

My bees are still out foraging despite the large blocks of fondant most hives are now topped with. I’m not sure what they’re collecting but it’s clearly worth the trip … and going to the initial trouble of finding it and telling other foragers about it.

Returning foragers

We usually take the amazing navigational abilities of our bees for granted. Those returning foragers are using navigational skills that evolved at least 100 million years ago while dinosaurs roamed the earth.

100 million years is a long time to develop a range of skills and subtleties; it’s no wonder we still only partially understand honey bee navigation. Of course, we don’t have to understand it to still marvel at their ability to find the way back.

And it’s worth also remembering that these navigation skills – many of which are based upon the angle of travel relative to the direction of the sun – also operate on dull, overcast days. But that’s a topic for another post …


References

  • Cardinal, S. and Danforth, B.N. (2011) ‘The Antiquity and Evolutionary History of Social Behavior in Bees’, PLOS ONE, 6(6), p. e21086. Available at: https://doi.org/10.1371/journal.pone.0021086.
  • Collett, M., Collett, T.S. and Wehner, R. (1999) ‘Calibration of vector navigation in desert ants’, Current Biology, 9(18), pp. 1031–1034. Available at: https://doi.org/10.1016/S0960-9822(99)80451-5.
  • Guilford, T. and Biro, D. (2014) ‘Route following and the pigeon’s familiar area map’, Journal of Experimental Biology, 217(2), pp. 169–179. Available at: https://doi.org/10.1242/jeb.092908.
  • Menzel, R. et al. (2005) ‘Honey bees navigate according to a map-like spatial memory’, Proceedings of the National Academy of Sciences, 102(8), pp. 3040–3045. Available at: https://doi.org/10.1073/pnas.0408550102.
  • Stone, T. et al. (2017) ‘An Anatomically Constrained Model for Path Integration in the Bee Brain’, Current Biology, 27(20), pp. 3069-3085.e11. Available at: https://doi.org/10.1016/j.cub.2017.08.052.

Intangible benefits

Synopsis : Some end of season thoughts on the intangible benefits of beekeeping. What does it provide other than honey and wax? 

Introduction

Central and Eastern Scotland were bathed in warm sunshine as I drove to Fife last Sunday. It was near-perfect weather for adding clearers to the hives in preparation for removing the last of the honey supers for extraction. Warm, but not too hot, breezy enough to keep any midges at bay but not so windy the bees would be flustered.

Lifting the supers was hard work, but it was lovely to be in the apiary, the bees were really mellow, there weren’t many wasps and it was a very enjoyable afternoon.

Doubly so because there were more weighty supers than expected and by the second apiary it was clear 2022 was looking like a bumper season.

Of course, I ran out of clearers … 🙁 .

Where do they go?

I checked the TARDIS-like shed but couldn’t find any spares so had to leave the last couple of hives to be cleared ‘manually’ i.e. shaking the bees off every frame.

Not the end of the world and – in good weather – something that doesn’t agitate the bees too much.

Somewhere in here are some spare clearers …

However, Monday dawned with leaden skies and almost no wind. Whatever weather was here was going to be staying.

By the time I got to the first apiary it was raining gently … but steadily.

By the time I had suited up, lit the smoker and arranged the Correx roofs to stack the supers in and under, it was still raining steadily … but much harder.

And by the time I’d retrieved and stacked the supers from the first few hives I was soaked.

It continued raining for several hours.

Have you noticed how heavy a beesuit gets when it’s all soggy?

And how slowly a sodden beesuit dries?

Real and intangible benefits

It was a really tough day.

I finished in the last apiary at about 4 pm, changed into the only dry things I had and set off on the five hour return journey back home.

As I was eating up the miles (and my belated lunch) on the A9 I got to think about why I keep bees.

It can’t just be because I like honey. There are excellent local honey’s sold in fancy organic cafe’s or up-market farm shops, or kilograms of mass-produced sweet stuff (labelled as honey) available from any supermarket you choose 1.

I estimate it costs well over £500 to start beekeeping. And by the time you’ve bought a few more hives, an extractor, a creamer, and a bottling machine you might have spent 40-times that amount.

You can buy a lot of lovely ‘artisan’ honey for £20,000.

So there has to be something other than just ‘liking honey’.

12ox hex jar with clear (runny) honey. The Apiarist

12ox hex jar …

There’s the pleasure of producing something high quality and desirable. It gives me a real sense of achievement. There are very few beekeepers who forget their first ever honey crop.

As a biologist, I find bees fascinating. And, as a virologist studying honey bee pathogens, I’m able to mix business and pleasure.

But I was beekeeping long before I started studying their diseases. The honey and the ‘beekeeping at work’ are tangible benefits.

As the miles piled up behind me I began to think instead of the intangible benefits of beekeeping.

What else have I gained from this engrossing pastime?

Other than the honey and smelling a bit foisty?

Does my bum look big in this?

As a callow youth I was probably less fashion-conscious than many of my contemporaries. I didn’t have the platform shoes, flares or a double-breasted frock coat 2. However, I was still acutely aware when I didn’t fit in, when I looked incongruous or when I was wearing something I thought others would ridicule.

Would I really have fitted in better wearing these?

Of course, being (a bit) older and (a little bit) wiser I realise now that it doesn’t really matter what others think. What’s more, other than the callow (or the shallow), most other people rarely notice, and certainly don’t care, what I wear.

Which, when you think about the amount of time I spend in a beesuit, is probably fortunate.

Saggy and baggy

It’s doubly-fortunate when you consider how profoundly unflattering a beesuit is. Shapeless and voluminous. They aren’t form-fitting 3 for obvious reasons … a sting might penetrate the cotton weave when stretched over the underlying soft tissue, but does no harm if there’s a billowing excess of material in the way.

Cold, clammy, heavy and baggy … a wet bee suit

I’ve just had my ‘best’ beesuit repaired. I bought it secondhand and it’s had well over a decade’s hard use. The veil had bee-sized holes in it, two of the pockets were torn, one zip pull was broken and all the cuff and ankle elastics were perished. For about £70 4 it’s now as good as new.

’As good as new’ but still profoundly unflattering 😉 .

But I simply don’t care.

I wear it when driving between apiaries, when I nip into a shop for a takeaway coffee or when I fill the car with petrol.

Unfortunately, on Monday my beesuit was soaked, so I drove home in my pyjamas. Yes, there were some odd looks at the filling station, but I’m a beekeeper … looking odd goes with the territory and I’ve learned not to care.

The physique of a Greek God

As I segue effortlessly from callow youth to early middle age I’m aware that I’m a little bit less like Charles Atlas and a little bit more like Charles Hawtrey.

Beekeeping is hard physical work.

I removed about 30 supers on Monday. If you assume that the average weight of a super is about 18 kg 5 the lifting, sorting, stacking and packing the car probably involved shifting a cumulative two metric tonnes of boxes.

Full super ready for extraction

Heavy, heavy, heavy

That’s a lot of lifting.

Many of the individual frames still contained a few stragglers which had to be shaken off. I simply hold one lug and bash the top bar sharply with the other hand. This requires a reasonable amount of finger strength … and leaves the heel of my hand rather bruised and battered after a long day of clearing supers.

As an aside, it’s always worth waiting for most of the honey to be capped (see the post last week), as frames of capped honey retain far fewer stragglers than frames of uncapped stores. As previously noted, a queenless hive’s supers hadn’t cleared overnight.

Beekeeper’s back is a very real problem and one that is well worth avoiding. I tripped carrying three full supers a couple of seasons ago and was in considerable pain for many weeks.

Good lifting technique, coupled with reasonable upper body strength from regular lifting, helps a lot.

So does not leaving stuff lying around the apiary to trip over 🙁 .

Naturally, my beesuit is so ill-fitting and shapeless that you can’t tell that I have the physique of a Greek God, but I can assure you that this is another of those intangible benefits of being an apiarist.

MAMIL 6

On a more serious note, the physical nature of beekeeping – in moderation and with appropriate technique – must be good for you. I’d much prefer to maintain or improve my back, arm and hand strength with weekly colony inspections than by going to the gym.

I prefer to do my weightlifting in the apiary

Not least because the Lycra outfits I’d have to wear to “fit in” at the gym would make my ‘Charles Hawtrey not Charles Atlas’ physique all too apparent 😉 .

Though, being a beekeeper, I probably wouldn’t care – see above.

‘Mainly dry’ 7

As a beekeeper living in Scotland I’ve become a little bit obsessive about climate and weather.

The climate has a fundamental impact on beekeeping. It influences the availability of natural forage and the time when it yields nectar. It determines when the season starts, how fast the colonies expand and when – like now – it’s effectively ’all over bar the shouting’.

The day-to-day weather influences when and if my queens get mated, how hot it will get in the bee shed and how wet I’ll get removing supers full of the ‘summer’ honey 🙁 .

Climate varies with latitude and longitude.

Weather can be a lot more localised.

By searching Weather Underground and similar sites for data uploaded from hobbyist weather stations 8 it’s usually possible to find a very local weather report.

19-26 August 2022 temperatures within a mile or so of my Fife apiary

I’m interested in conditions needed for queen mating in the sometimes iffy Scottish summers. By checking the weather records once queens start laying it’s very clear that the – usually quoted – ’sunny, over 20°C and light winds’ is a load of nonsense.

19-26 August 2022 temperatures in my west coast apiary

I currently live so remotely that I installed my own weather station to get a record of the actual local conditions. This close to the Atlantic they can vary wildly in just a few hours – we had heavy rain this morning 9, but lovely ‘softy Southern queen mating’ weather all afternoon 😉 .

Getting out and about

Some of these peripheral interests will have tangible benefits for my beekeeping. However, and of more relevance to this post, I’m consequently a lot more in tune with what the weather is likely to do over the next 12-24 hours.

The BBC might claim it’s going to be ‘wet with strong westerlies all day’ in north west Scotland (a region that stretches at least 200 miles from Durness to Oban), but I now know it will probably blow through by late morning and be fine in the afternoon.

I could open some hives, but I might instead go walking or cycling.

Sanna beach

Inevitably, living somewhere that gets 1-2 metres of rain a year, we see a lot of clouds. My more-than-passing interest in the weather has expanded into an appreciation of clouds and cloud formations. As I drove west along Glen Tarbert at the beginning of the month, in a car laden down with squeaking poly supers 10, the clouds merged and folded into one another above me.

Clouds, Glen Tarbert … mammatus?

At least, that’s what it looked like.

Beekeeping, other than in a bee shed I suppose, is of necessity an outdoor activity. By trying to understand how the climate and weather helps or hinders my bees I’ve learnt how to take advantage of unexpected – or at least not forecasted – good weather for other interests.

Of course, I don’t always get it right … I spent an hour in a remote bus shelter during a violent thunderstorm last week. It would have been spectacular had I not been so concerned that the bus shelter was largely made of metal …

Phenology

I’ve discussed phenology – ‘the timing of periodic biological phenomena in relation to climatic conditions’recently. This is much more interesting than the weather per se.

There are tangible benefits for beekeeping. If you realise the migrant birds are late to arrive you shouldn’t be surprised if the colonies are less well developed when you conduct the early spring inspections.

But the intangible benefits outweigh these.

Just having an appreciation of how the year builds, the flowering of the plants and trees, the arrival of animals and the onset of the breeding season, is intensely rewarding. I expect the sand martins by late March, but am disappointed if I’ve not seen a swift by the 8th of May. I look forward to their arrival. The siskins will disappear for a couple of months at the end of the year to feed on pine cones in the forests … but they’ll be back in January.

Siskin

I spent the best part of three decades sitting in cramped offices, reading or writing papers and grant applications. Long weeks and weekends of work often left me isolated from the natural environment.

Although I was always interested in natural history, beekeeping has raised my awareness of the cyclical annual events in the ’rhythm of the seasons’.

That’s enough cod-philosophy … almost time to move on.

Be observant because it will help your beekeeping, but be observant because it will reward you in many other ways as well.

Organisation and patience

When I first started thinking about the topic of intangible benefits I considered including a commentary on how waiting for queens to get mated has instilled a Zen-like patience to the rest of my life.

Likewise, I planned to discuss how the organisation needed to manage the roofs, boxes, boards, frames, food, miticides etc for 30 colonies – many on the other side of the country – had brought order to my shambolic logistical skills.

However, doing either of these would have made this post a work of fiction 🙁 .

I dare say my organisational skills have improved, but I still ran out of clearers last week. I also used a clearer on a suspected queenless colony. Had I thought about this – and been a little more organised – I’d have not bothered with a clearer on that colony as it wasn’t going to clear anyway.

So, my beekeeping-related organisational skills still need honing, and there’s little-to-no evidence of any improvement in the rest of my life.

Chaos? What chaos?

Although I am a lot better at patiently waiting for queens to mate and start laying, there’s unfortunately been no noticeable improvement (I’m regularly reminded) in anything else.

Everyone is interested in bees 11

If you walk around for long enough wearing a beesuit you’ll get asked about bees and honey.

This can lead to all sorts of interesting or surreal conversations about honey bees vs. bumble bees. There’s a lot of confusion out there. I’ve been asked about waspkeeping, and candle making and lots about tree bumblebees (Bombus hypnorum – very interesting … these arrived in the UK in 2001 and have now spread as far north as southern Scotland).

Of course, few are interested in the arrival and spread of tree bumblebees, but they do want to know why there is a ‘swarm’ of bees around their bird box (these are males waiting for the virgin queens to emerge).

Although some of the conversations might start from an ill-informed position, there is real interest in bees. It’s a good opportunity to emphasise that, although honey bees aren’t threatened with extinction, some bees are.

Plant native wild flowers, stop using pesticides in the garden, don’t believe all the ’beewash’ you read in the supermarket … and don’t ‘sponsor a hive’.

Of course, some of these conversations lead to honey sales 🙂 .

A fifteen minute conversation might only result in the sale of a single jar of honey. The intangible benefits are the conversation, the people I meet and the new things I learn.

So much easier sold by the bucket

Or you might hit the jackpot and sell a complete bucket. That of course is a real financial benefit … and think of all that jarring and labelling you don’t need to do 😉 .

Hay fever

Probably half the conversations I have about bees and honey involve a discussion of the benefits of local honey for hay fever sufferers. Although I try and correct this pseudo-science I don’t do so with sufficient force to impact honey sales.

And a final hint for the uninitiated about selling honey … carry a jar or two of honey in the car. A casual request for one jar might lead to a regular monthly order for a gross.

Just sayin’ 😉 .

Gifts

Not everyone likes honey, but everyone knows someone who likes honey.

I think this is the reason why honey makes such a great gift. If you’re saying thank you for the invitation to dinner, or for looking after the dog, or for that large bag of runner beans, there is nothing to beat a jar or two of honey.

It’s a handmade gift, it’s beautifully presented, it is exceptionally high quality and – other than the jars that came from the same bucket – totally unique.

In these regards it is a much better present than a bottle of wine … though wine and honey is also a winning combination.

A winning combination

The gift of a jar of honey is more personal, more thoughtful and much more likely lead to a conversation … ”Wow, thank you, is this honey from your own bees?”.

How many times have you been asked whether the bottle of merlot came from your own vineyard? In fact, how many times is the bottle of wine accepted without comment and then immediately put aside?

It doesn’t have to be honey of course – it could be candles (if they’re better than mine) or beeswax wraps or propolis tincture.

It’s the fact that it’s homemade, unique and high quality that counts.

I think this was the first of the intangible benefits I became aware of when I started beekeeping. Managing the colonies, rearing the queens and harvesting the honey is very rewarding … but it’s great that the honey brings pleasure to nearly everyone.


 

More droning on …

Synopsis : Drones are now being evicted from colonies. How and why does a honey bee colony regulate drone numbers?

Introduction

Over the course of the last eight years posts on The Apiarist have got longer. This year, posts are now five times the length of the 2014 average. I’ve written – and hopefully, you’ll have already read – more words this year than are in The Hobbit.

If this continues until the end of the year we’ll have exceeded the word count in Tolkien’s The Two Towers.

This is probably unsustainable 1.

The increase is explained in part by the complexity of some topics. It’s compounded by the need to provide some contextual information … and by my prolixity 2. The latter is unavoidable, the former is probably necessary, not least because of the significant churn in new beekeepers.

A topic needs to be introduced, explained, justified and concluded.

Without this contextual information a post on oxalic acid trickling could be just:

5 ml of 3.2% w/v per seam when they’re broodless.

And where’s the fun in reading that?

Or writing it?

Furthermore, it’s probably of little use to a beginner who might not know what w/v means. Or what a seam is … or for that matter why being broodless is critical.

Keeping it topical

To maximise the income from site advertising I need to keep readers returning. This means the choice of topics should be important.

However, although some topics are chosen because they’re key concepts in the art and science of beekeeping, the majority are picked simply because I find them interesting.

And this week is one of the latter as I’m going to be droning on about … drones.

Specifically about drone numbers in the colony.

This was prompted by seeing the first drones of the season turfed out of the hive.

Dead drone at hive entrance

Another one bites the dust

Seeing this coincided with me discovering an interesting paper on how the queen’s laying history influences whether she produces drone or worker brood. This, inevitably, led me to other papers on drone production and discussions of how the colony controls drone numbers 3.

Drones are topical now because their days in your colonies are limited.

Already the colony will be producing significantly less drone brood than three months ago. The drones the colony has already produced will still 4 be flying strongly on good days.

However, when in the hive they will be being increasingly harassed by the workers.

Herding drones

If you open a colony very gently in the next few weeks 5 you might find the corners of the box contain high numbers of drones. The photo above was taken in late August and I’ve seen it several times late in the season. My interpretation is that it’s the only location in the hive in which drones can escape harassment by the workers.

Drone eviction

Drones ‘cost’ the colony a lot to maintain. A drone consumes about four times the amount of food than a worker (Winston, 1987). Therefore, once the fitness benefit of keeping drones falls below the expected costs needed to keep them they become ’surplus to requirements’. At this point the workers turf them out of the hive.

Evicted drones cannot feed themselves, so they perish.

It’s a tough life.

Interestingly, workers preferentially evict old drones. Presumably younger drones are more likely to fly strongly and mate with a virgin queen. Additionally, sperm viability in older drones is reduced, so their genes (and therefore those of the colony) are less likely to be passed on.

This ‘cost’ of maintaining drones is influenced by both the colony and the environment. For example, queenright colonies (which, by definition, have less need for drones) evict more drones than queenless colonies in the autumn, as nectar becomes limiting.

Although most beekeepers associate drone eviction with late summer/early autumn it also occurs when nectar is in short supply e.g. during the ‘June gap’.

It has also been suggested that drone eviction rates are related to colony size. Small queenright nucs, which have less need for drones, are more likely to evict than a full colony.

There’s still a lot we don’t know about drone eviction. For example, since drones tend to accumulate in queenless colonies, do these preferentially evict related drones to maintain potential genetic diversity in the population? 6

Hannibal the cannibal

Allowing an unfertilised egg to hatch, feeding the larva, incubating the pupa to emergence and then maintaining the resulting drone is a waste of resources if conditions are not appropriate. For example, doing this during a nectar dearth – particularly when drones are unlikely to be required for mating – makes no sense 7.

Therefore, in early spring and late autumn, workers cannibalise developing drone larvae. Effectively they are recycling colony resources. They preferentially cannibalise young larvae rather than older larvae. This makes sense as young larvae are going to need more food to reach maturity.

As above, queenless colonies cannibalise less queen-laid 8 drone larvae than queenright colonies.

In addition, some studies have shown that colonies with abundant adult drones cannibalise a greater proportion of developing drones. Again, this makes reasonable sense. Why rear more if you’ve got enough already?

However, to me it makes ‘reasonable’, but not ‘complete’ sense. Drones being reared as larvae are genetically related to the colony, adult drones may well not be. Drones that have drifted in from adjacent hives may therefore reduce the likelihood of the colony passing on its genes under environmental conditions which favour larval destruction but not eviction of adult drones.

Someone needs to look into this in a bit more detail 😉 .

There are lots of other aspects of larval cannibalism that are not understood. For example, how do workers discriminate between drone and worker larvae? Can they – as the queen can – measure the cell dimensions? Drone and worker brood pheromones differ from day 3 or 4. This seems a bit late to account for the cannibalisation of young larvae?

The influence of the queen

Since workers may cannibalise developing larvae 9 at different rates (drone vs. worker) it’s necessary to measure the colony’s egg sex allocation to see how the queen may influence drone numbers.

Only a few studies have done this …

There are experiments that suggest (they’re not definitive) that queens in continuously fed colonies lay more drone eggs in spring and summer than in autumn. This implies that day length or temperature may influence the queen, but it could also be a response to colony strength i.e. the queen lays more unfertilised eggs in a colony increasing in size, than in one decreasing.

In addition – and this is where I started down this rabbit hole in the first place – the egg laying history of the queen influences her current egg laying activity.

This easy-to-understand study was conducted by Katie Wharton and colleagues (Wharton, 2007). They confined queens for a period on either drone (DC) or worker comb (WC) – ensuring the queen could only lay drone or worker eggs for 4 days. They then transferred the queens to frames containing a 50:50 mix of drone and worker comb and recorded the amount of drone or worker eggs laid over 24 hours.

WC queens laid more drone eggs but the same amount of worker eggs as DC queens

There was a marked difference in the egg laying activity of the DC or WC queens when given the choice of laying drone or worker eggs. Although both the DC and WC queens laid similar amounts of worker eggs, the WC queens produced significantly more drone eggs as well.

Egg laying history or drone brood quantification?

This is a good study. The authors controlled for a variety of factors including season, colony size and food availability.

They additionally excluded the possibility that the egg laying activity of the queen was influenced by preferential cleaning of particular cells types by the workers, or by the workers backfilling certain cell types with nectar.

Finally, Wharton and colleagues allowed the colony to rear the eggs laid to pupation. The bias already observed was retained i.e. colonies headed by WC queens reared significantly more drone pupae than those headed by DC queens. The workers did not ‘correct’ the negative feedback exhibited by the WC queen, for example by preferentially cannibalising drone brood.

Although I termed this the ‘egg laying history’ of the queen a few paragraphs ago there is another interpretation.

The worker or drone comb already laid up by the queen – during the 4 day confinement period – remained in the colony. It’s therefore possible that the egg laying activity of the queen was influenced by the amount of drone brood already present in the colony.

Either explanation is intriguing.

How does the queen ‘count’ the number of drone or worker eggs she’s laid in the recent past? Alternatively, how does she quantify the amount of drone brood in the colony?

But what about the workers?

The Wharton study largely excluded the possibility that there was preferential cleaning of drone or worker cells by the workers in the hive. In fact, earlier studies have indicated that cell cleaning continues almost constantly and workers were equally likely to clean worker or drone cells.

The Wharton study also addressed – and excluded – the possibility that differences in the backfilling of drone or worker cells might influence egg laying.

However, it’s not understood what determines whether drone cells get backfilled with nectar by workers. My colonies are starting to do this now. Do the workers fill drone cells with nectar because the queen hasn’t laid in these cells or because they only backfill drone cells late in the season?

The former suggests that there is some sort of competition between the egg laying activity by the queen and nectar storage by workers. In contrast, the latter suggests that there are environmental triggers that influence this worker activity.

Or both … of course 😉 .

Comb building

In contrast to some of the studies outlined above, comb building is easy to monitor and – perhaps consequently 10 – has been well studied.

I’ve already discussed comb building in a recent post about queenless colonies. These preferentially build drone comb (Smith, 2018).

What else influences drone comb production?

Probably the two strongest determinants are the amount of drone comb already in the nest and the season.

Drone comb production is reduced in colonies that already contain lots of drone comb. Many beekeepers never observe this as they only use frames containing worker foundation. The workers squeeze in little patches of drone comb – often in the corners of the frame – but it never exceeds 5% of the total.

Colonies often prefer to build drone comb when given the choice

In contrast, natural nests contain 15-20% drone comb. That’s equivalent to two full frames in a National-sized hive. Once drone comb approaches this level a negative feedback loop operates and the workers build less drone comb. The negative influence of this drone comb (on building more drone comb) is enhanced if the comb contains drone brood.

Colonies drawing comb now (and certainly in the next month or two) will build worker comb. Some beekeepers exploit this to get lovely new worker frames drawn – nucs are particularly good at this 11. In contrast, drone comb is drawn in spring and early summer. The season – presumably day length and temperature – therefore influences drone comb production, and hence drone production.

A thousand words

Well, nearer 2000.

As we near the end of the season we start to see drones evicted from our colonies. It’s interesting to think about the interplay of events that resulted in the colony producing those drones in the first place … and how and why the colony regulates drone production throughout the season.

Wharton (2007) neatly summarised the five stages from comb building to adult drone eviction.

Drone production and maintenance in a honeybee colony

I’ve dealt with these in reverse order because that was the best fit with the photo of the dead drone on the landing board that I started with.

There’s a lot we still don’t understand about the regulation of drone numbers. In particular, I think the majority of studies have ignored the influence of adult drone numbers on any of five stages illustrated above.

This is an important omission as drones move more or less freely between hives. That means that adult drones may well be genetically unrelated to the colony.

Perhaps this means that adult drones do not influence drone production? After all, if they did negatively influence drone production – as suggested above – it would potentially limit the ability of a colony to reproduce its genes. Evolutionarily this doesn’t make sense (at least, to me).

There are a couple of studies that have tried to determine the influence of adult drones, but they have produced conflicting results. Rinderer (1985) added drones to a colony which consequently reduced drone brood production. However, Henderson (1994) did the opposite and showed that removal of adult drones had no effect on drone brood production.

There’s clearly lots more to do …


Notes

I wrote this late on Thursday night. While doing so I watched the page views of my four year old post on Mad honey go ‘off the scale’ (which for a beekeeping site means hundreds of views per hour). The interest wasn’t sparked by my erudite description of grayanotoxin intoxication. Instead it was related to a video of a ‘stoned’ Turkish brown bear cub rescued after eating honey produced from rhododendron nectar.

It’s now abundantly clear that if I want to maintain my outrageous advertising income I should probably write more about hallucinogenic honey and less about the evolutionary subtleties of honey bee sex ratio determination.

That’ll teach me 😉

References

Boes, K.E. (2010) ‘Honeybee colony drone production and maintenance in accordance with environmental factors: an interplay of queen and worker decisions’, Insectes Sociaux, 57(1), pp. 1–9. Available at: https://doi.org/10.1007/s00040-009-0046-9.
Henderson, C.E. (1994) ‘Influence of the presence of adult drones on the further production of drones in honey bee (Apis mellifera L) colonies’, Apidologie, 25(1), pp. 31–37. Available at: https://doi.org/10.1051/apido:19940104.
Rinderer, T.E. et al. (1985) ‘Male Reproductive Parasitism: A Factor in the Africanization of European Honey-Bee Populations’, Science, 228(4703), pp. 1119–1121. Available at: https://doi.org/10.1126/science.228.4703.1119.
Smith, M.L. (2018) ‘Queenless honey bees build infrastructure for direct reproduction until their new queen proves her worth’, Evolution, 72(12), pp. 2810–2817. Available at: https://doi.org/10.1111/evo.13628.
Wharton, K.E. et al. (2007) ‘The honeybee queen influences the regulation of colony drone production’, Behavioral Ecology, 18(6), pp. 1092–1099. Available at: https://doi.org/10.1093/beheco/arm086.
Winston, M.L. (1987) The Biology of the Honey Bee. Cambridge, Massachusetts: Harvard University Press.