Life in the garden

The selfish ivy had taken everything out of the soil for itself. As I dug up the echinacea, verbena and thyme to replant in pots, I realised that few but the most stubborn plants would grow in this unfriendly earth. Further along the walled bed, two small trees had littered the soil with fallen leaves and not even the Japanese anemone nor the lemon balm would venture any further into the shade.

Then I had an idea. Bees, butterflies and other garden visitors need water as well as food. If I couldn’t grow any flowers for wildlife to eat, then I would give it a place to drink instead.

A cinnabar moth resting on a cool leaf. Non-flowering foliage is as important as the flowers in the garden, because it provides a place for wildlife to hide, shelter and rest.

A quick search around the house and garden and I found everything that I needed to create two mini-wildlife ponds.

Tip: The garden is a great place to find new uses for old things. I also feel that we rely too much on recycling. The next time you think about buying garden accessories have a look around the home or second-hand shops first. A bucket with a broken handle could make a frog pond, a cracked flower pot for a toad house, chipped cups for bird feeders and old serving forks and spoons can be used as stakes for plants.

An empty plastic container and a stained washing-up bowl – both in the queue for a trip to Harefield’s recycling skip – were just the right sizes for my mini ponds. I dug a hole in the earth for each and buried the bowls up to the rims to make it easy for hedgehogs to stop by and dip in for a drink.

The ivy is home to many creatures in our garden, including spiders who usually walk out on their webs when I disturb them doing the gardening.

Next, I poured gravel into the bottom and made a pile of stone ‘steps’ for frogs, toads or newts to climb in and out. Larger stones and broken paving slabs surrounded the edges. That done, I filled up the ponds with tap water – and some dechlorinator (it hasn’t rained enough lately to collect rainwater in buckets) – and added duckweed and hornwort from the larger fish and frog ponds.

Tip: Duckweed and hornwort can quickly grow and become a nuisance. I find it easy to manage by removing a handful now and then as compost for the garden or to put into the bird bath and rain buckets. The plants seem to keep the still water clear and to deter mosquito larvae as well.

Finally, a few pieces of crockery filled with pebbles made watering holes for thirsty insects. Here are the results:

It wasn’t long before the frogs, and the snails, found the new garden ponds.

A walk in the garden at night revealed that a lot of wildlife comes out after the dark like this trail of snails climbing over the plant labels to the pond.

Although some still prefer our more established frog pond.

We have a lot of slugs in the garden too, but, as you might guess, we don’t use slug-and-snail pellets. Any slugs that I find on the Japanese anemone, which is their favourite thing, are put on the compost bins where they can eat to their hearts’ content.

The mini-wildlife ponds are also the perfect place for baby snails but overall life in the garden sorts itself out, and the frogs seem to keep the slug and snail population in balance.

As you might imagine, our garden is also pesticide-free and weedkiller-free. In fact, I was once told by a gardener, when asking about how to control the bamboo and bindweed last year, that the bees don’t mind Roundup. I didn’t believe him and I’m glad to say that we found another gardener willing to dig out the bamboo (an expert job because its roots were entwined around the roots of the smoke tree) rather than poison it. Meanwhile, John and I weeded out the bindweed and covered the area using garden sheeting and gravel.

We’ll never be rid of either (bindweed seeds, for example, can live in the soil for many years), but we manage both quite well by physical methods – digging, hoeing and weeding.

The old bamboo grove is now used as a bird-feeding station. Here, the birds can feast on fat balls and splash about in the bath and make as much mess as they want on the rhizome-riddled earth. The area is sheltered by the smoke tree and bushes to allow small birds to make a quick exit if the sparrowhawk flies past.

As a thank you, the birds have left us some beautiful flowers this year from other gardens, such as this love-in-a-mist. Birds are very good gardeners.

Life is always very busy in the garden.

After the bamboo was cut down, several thistles sprung up in its place. John and I kept the largest thistle next to the fence for the sweat bees. It has been a popular breakfast bar.

On the gravel patch, I planned to plant mini-wildflower meadows in pots but the garden had other ideas. This summer’s surprise is the butterfly-and-caterpillar habitat that has sprung up in the form of a toadflax meadow.

The carder bees also buzz around the purple flowers all day long – toadflax is a rewarding plant for wildlife.

While my mason bees that I ordered earlier in spring fell victim to the backwinter and an army of ants, a single local mason bee found the insect hotel when the weather warmed up again. She worked very hard for almost a month to fill as many tubes as possible with her eggs and food for her larvae.

The mason bee was too busy to keep up with her housework this year and often left piles of yellow pollen outside her front door.

Sometimes she had a lie-in on a Sunday morning.

I last saw our mason bee resting on the fence, her exhausted and bedraggled body fit to drop, and then she was gone. A fortnight later, I realised that she wasn’t coming back and that three of the tubes were only partly finished. So I completed her work by making mud plugs myself and hoped for the best for next spring.

The leafcutters moved in next and have been busy filling up the remaining tubes.

Another resident has been watching their progress with interest.

As far as I can tell, he has not caused any mischief and so has not been evicted.

The ants made up for their earlier destruction of my mason bee cocoons by allowing me to watch this year’s queens fly away to start new nests. They didn’t fly very far it seemed and probably we will have more ant nests on the lawn again.

The honeybees returned after the June gap for their annual crop of a flowering shrub around the fir tree. As a beekeeper, I have an interest in planting a garden that is pleasing to bees. This summer, the salvia and scabiosa have been the clear winners, probably because they have flourished and grown rapidly in the sun. The honeybees have also discovered the lemon balm which is in flower and a few bumble bees have opted for the more traditional choice of our lavender bush.

The scabiosa has been busy entertaining bee and hoverfly visitors all day long. This carder bee can’t wait to get in on the action.

I’m also delighted that our myrtle tree is in flower for the first time since it was planted in the garden, although it has not yet produced enough flowers to delight the pollinators.

Of course, it’s not all about the birds and the bees. On occasion, we have human visitors too.

My mum and stepdad enjoying Sunday lunch in the garden yesterday.

They provide something interesting for the fish to look at.

Life in the garden is precarious and it can all change as quickly as it came. Already the plants seem too far ahead of the season and the blackberries are beginning to ripen over the fence. I have found a new hobby in collecting my own seeds and cuttings to grow more of the plants and flowers that the wildlife in our garden loves most. Bluebell bulbs can be divided and planted under the smoke tree in autumn, seeds are being collected from the salvia and seedheads from the scabiosa to provide more forage for next year’s bees, and the toadflax and rose campion ‘alba’ are being encouraged to sprout everywhere for next year’s butterflies.

This week on BBC begins The British Garden: Life and Death on Your Lawn looking at how well British gardens support wildlife. From the frog ponds in the shady flower beds to the compost bins and piles of logs and leaves, I like to think that our garden supports a lot of wildlife and that there is still much more to discover beyond our back door.

 

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The backwinter

In Finland a cold snap in spring is called ‘backwinter’, because winter has come back. Yet it was only a few weeks ago in April that everything was coming to life in the garden.

As this is my first year as a Maund, I took a photo of these delicate white blooms on a shrubby bush on Maundy Thursday, which fell on Thursday 13 April. In the Christian calendar Maundy Thursday marks the beginning of the three-day period before Easter, while in many Pagan beliefs it was Green Thursday and celebrated the return of nature in spring. Until not so very long ago, and perhaps it happens still, it was traditional for country churches to decorate the altar with white-and-green flowers for Maundy Thursday.

But on the first of May the unopened buds were stubbornly refusing to wake up and everything was cold and still in the garden once more. In London winter coats have made a comeback. I was tempted to pick a bunch of the white flowers for a vase in the kitchen window, before they all fell off, but then remembered that there is a wealth of folklore warning us not to pick white blossoms and bring them indoors, unless you also want to invite misfortune.

My mason bees have not yet emerged from their cocoons and now I fear they won’t. Even if they do awake, our apple blossom has fallen and the dandelions have gone to seed puffs. All that remains of spring is the memory of glorious yellow lions on the lawn shaking their manes at the sun, pretty cowslips gathering in hedgerows and bright orange marmalade flies hovering on leaves (both the marmalade fly and the cowslips below taken on a visit to the old cathedral city of Wells in April).

The tiniest flowers in the garden, escapees from the wild, appear to be the hardiest like this Herb Robert (Geranium robertianum), I think, growing around the apple tree. If it is a Herb Robert, then it’s also known as dragon’s blood. Well, just look at those splendid red claws.

In the pond the frogs have returned, but they too were fooled by the warmer temperatures in spring and spawned too early. The frog spawn became frothy with the black eggs turning white as temperatures dropped, and it has now all dissolved away. So it seems we will have no tadpoles either this year. At least the frogs have the fish for company.

And the occasional eyes-in-the-sky to stare at.

At the apiary the queens are coming. It seems that the bees do sometimes read my blog. Last bank holiday Monday, I found five queen cells (three unsealed) in Hope’s hive (Hope was still inside the hive) and all were on an old brood frame that needed to be swapped for a new frame. I took out the queen cells to give to Patience’s hive (who are so ill-tempered they are most likely queenless) and gave Hope’s hive another new brood frame (well, two actually) to play with. As there were no other queen cells (that I could see) in Hope’s hive, and the bees had two new frames to work and a cold week ahead, I thought it was safe to close up and wait till Saturday to inspect again. Not so.

Yesterday, we found out that the bees had not been told about backwinter and they had been very busy. During the beginner session at the apiary, around three or four frames (maybe more but it was difficult to keep count during the class) had queen cells – some sealed and some unsealed – and this time the queen could not be found. Instead, we did a split of the hive by removing a frame of queen cells and putting these with some frames of brood, bees and stores in the polynuc. After the past year of failed queens, I’m not going to complain about having too many queens this year!

In Patience’s hive the queen cells were still intact and being nursed, it seemed, by the workers. So we have three hives waiting for new queens to emerge. Quite exciting!

After the beginners had left the apiary, Jochen and I went with John Chapple to look at his hives, which are all doing well after their shook swarms, with the exception of one that might be headed by a drone layer or else entirely queenless. John had brought a few empty queen cells for show-and-tell earlier and Kathy had talked about dealing with queen cells, splits and culls.

For me, the queen cell shown above was a rare glimpse into the secret life of the honeybee queen. It had been found perfectly intact and before the workers could efficiently take it down to make use of the wax. You can see where the virgin queen had carefully ‘taken off the lid’ as she emerged from her cell into the complete darkness of the hive. As I held the cell in my hand, I wondered whether she was the first of her sisters to emerge and whether she would stay to rule the hive or fly off in a swarm. But even when still inside their cells, the ‘unborn’ queens sometimes ‘quack’ to make the others aware of their presence and of the deadly duals that may follow if they cross each other’s path after emergence.

As a beekeeper I can only wait-and-see which queens will emerge first in our hives – and keep my fingers crossed for a ‘backspring’ to welcome them.

From one secret dark place of the earth to another – mysterious glowing eggs seen in the caves at Cheddar Gorge in April. I’ll leave you to contemplate this strange mystery, while the bees are left to theirs.

Springing to life

Spring is such an exciting time of year with everything springing to life. I picked the dandelions off the lawn yesterday, before John mowed, to save them for a salve. There are plenty of dandelions left in the flower beds for the bees and other pollinators.

I love these golden flowers that open like bright stars to greet the sun or which sometimes seem to resemble a fluffy lion’s mane. How can they be called weeds? Folklorists suggest that dandelions were once a ‘shepherd’s clock’ because they open at sunrise and close at sunset. As the dandelions in the garden were all wide open, I took it as an indication that it would be a good day for beekeeping.

At the apiary both mine and Emily’s hives were flying well. I arrived to get started before the crowds – the Grand National was on later and I didn’t want to miss the start. First, a look inside Hope’s hive.

Emily had moved this colony from the polynuc to a full-sized hive last weekend and I wanted to see how they were doing (also, congratulations Emily for winning the Walton’s blog award!). As you can see they are doing very well, almost bursting from the seams, in fact. It is such a different picture for this colony than for this time last spring where they had come out of winter very weak. I’m convinced that the insulation provided in the past year, and that spending the winter in a polynuc (thanks Thomas Bickerdike), has saved this colony from dying out.

Hope’s bees have really got back on their feet – well done girls! – and were buzzing very loudly and contentedly, it was a deep vibrating sound and not high pitched. They had taken down most of the honey from the beautiful honeycomb sculptures in the roof, which I removed without much fuss, and the workers in the brood box were drawing out fresh golden comb on the new frames.

I found Hope on the third frame in and caged her just in case I found queen cells further along. I didn’t find queen cells but took the opportunity, while the queen was caged, to take out two old brood frames, shaking off the bees, and to put in two new frames. We’re taking a frame-by-frame approach to the comb change for the hive this year. Because the bees have only just got back on their feet, a full shook swarm seems a bit harsh. They have been moved to a clean hive and only three old frames remain which we can swop out as they continue to build up.

Emily arrived as I was closing up and writing the hive records. As you can see, the bees are still trying to eat their homework.

Next, Emily looked inside Patience’s hive as a small group of visitors arrived and I busied myself with getting our hive equipment ready for a comb change for this colony, either at or after Easter. I could hear lots of questions being asked and all seemed to be going well.

Patience’s colony had been left to overwinter inside a brood box and a super with insulated frames and a ‘winter blanket’ around the hive. The queen had been laying in the super (as is probably to be expected when the queen excluder has been left off overwinter), but it was largely drone brood and could even be an advantage for the upcoming comb change.

The varroa mite tends to be more attracted to drone brood because drones have a longer period of gestation inside their cells – they emerge around day 22 to 24, unlike workers who emerge around day 21, or the queen who emerges around day 16. This is probably because the queen and workers have a lot more work to do inside the hive and are in more of a hurry to get started!

Where a lot of drone brood has been laid in the super, we might be carrying out effective chemical-free varroa control by getting rid of these frames during a comb change. We might use a decapping fork to decap the drone brood and see whether there are mites inside the cells before they are discarded.

While there were a lot of bees inside Patience’s hive, there was little brood, no eggs and no sight of the queen. But it is early days yet and the bees were well behaved and keeping busy. As usual, they probably have a much better idea of what is going on inside the hive than we do. So, we may give the colony and its queen a couple more weeks to pick up before making a decision about whether they need to be requeened or combined with Hope’s colony – the latter option only providing that they are healthy with low levels of disease.

As we were closing up, a worker bee managed to sting through my thin marigold gloves. I had a bad reaction to a sting several years ago – my first honeybee sting, in fact, and this was only my second – that had seen a short trip to A&E for some swelling and nausea. I put on some clove oil as my hand started to burn, which had an almost immediate effect on the pain, and went to sit down in the cool shade of the apiary benches. One of the apiary visitors also gave me an antihistamine.

Luckily, an hour or so passed and I felt fine. John picked me up and I was home in time to watch the Grand National. John had put a bet on for my horse, One for Arthur, which won by the way!

With the first smoker of the year having been lit, the bees looking in a much better position than they did last spring, and the dandelions marinating in olive oil in the sunshine, it had not been a bad day’s beekeeping.

Meantime, Emily, Tom and I have been nominated again for best beekeeping blogs by WhatShed. Ealing beekeeping blogs are really doing very well this year!

I plan on making some simple dandelion salves with the marinated oil and beeswax for hands and chapped skin after gardening. I’ll let you know how it goes.

Dandelions have so many uses and were once considered a very useful herb in folk medicine and cooking. I wonder when we stopped noticing the usefulness of ‘weeds’? As Culpeper wrote in his Complete Herbal in the 17th century, the French and Dutch seemed to commonly use dandelions in spring, and to which he concluded with his usual tact that “foreign physicians are not so selfish as ours are, but more communicative of the virtues of plants to people”.

Winter studies: The poison honey

Bee Anthophora RCP06-07 085

© Dr Henry Oakeley

“In the summer, in the College garden, the woolly foxglove, Digitalis lanata, is visited by little bees which become stuporose and lie upside down in the flowers, seeming unable to fly away when disturbed.” –Dr Henry Oakeley, Garden Fellow at the Royal College of Physicians (RCP) Medicinal Garden.

I became fascinated with the idea of ‘poisonous honey’ when I worked at the College. Watching bees foraging on the intoxicating inhabitants of the physicians’ Medicinal Garden, my imagination ran wild with thoughts of insects tempted by sinister sweetness, putrid pollen and foul fruit. What seductively dark nectar would the bees return to the hive to convert into undesirable honey? When I asked Henry, he told me the story of the bees in the woolly foxgloves and he kindly sent two beautiful photographs taken in the College garden.

Bee Anthophora RCP06-07 089

© Dr Henry Oakeley | Poison honey and a whodunnit bee too, how exciting! Anthophora or Anthidium manicatum? See Mark’s comments below.

The colour and flavour of honey comes from the variety of nectar sources visited by the bees. From spring mint and summer blackberry to autumn woods and bitter ivy, the taste and smell of honey can evoke intense reactions, not always good. The strong flavour of privet honey, for example, is described as ‘objectionable’ in Collins Beekeeper’s Bible, while Ted Hooper in A Guide to Bees & Honey confesses: “I cannot say I have ever found much wrong with it”. But whether you like ivy, heather or rapeseed, ‘unpalatable’ honey is a matter of personal taste.

What, then, of honey with truly ‘undesirable’ qualities from the nectar that is gathered, being harmful to bees or humans, or both? In this post, I’m going to look at the possible toxicity of honey from the nectar or pollen of plants rather than artificial contamination.

“Just when you thought that honey was always a wonderful health food,” says Henry, pointing me in the direction of rhododendron – a common culprit of toxic honey that can be harmful to bees and humans. According to Wikipedia, a chemical group of toxins called grayanotoxins found in rhododendrons and other plants of the family Ericaceae may, very rarely, cause a poisonous reaction of ‘honey intoxication’ or ‘rhododendron poisoning’.

Rhododendron and clouds in Japan

Image: Rhododendron and vast clouds in Japan | 松岡明芳 via CC BY-SA 3.0.

Xenophon and his Greek army retreated ill from Persia in 399BC as a result of ‘toxic honey’ and Pompey’s soldiers fell foul of ‘maddening honey’ in the Third Mithridatic War in 65BC. These historical accounts name varieties of rhododendron honey as causing a “feeling of drunkeness, to vomiting and purging, and madness that lasted for days” (Collins). A botanist’s tale of poison honey is given by Frank Kingdon-Ward (1885–1958), during his travels in northern Burma towards Tibet. He recounts symptoms similar to acute alcohol poisoning, suffered along with his travelling companions, after eating honey produced in the rhododendron season. The local Tibetans ate the honey without ill effects (Collins).

Piers Moore Ede vividly describes sipping the ‘wondrous toxic honey’ of rhododendron flowers collected by the honey hunters of Nepal: “It resembled drunkenness at first, but then became visual, like a magic mushroom trip I remembered from university. Painted dots were dripping across my irises like technicolor rain. My body felt light and tingly, filled with warm rushes and heat-bursts. It was wild and strangely wonderful” (Honey and Dust: Travels in search of sweetness).

Manaslu-Circuit_Rhododendron_Forest

Image: Rhododendron forest on Manaslu circuit, Nepal | Spencer Weart via CC BY-SA 3.0.

An incident of poisoning reported in honeybee colonies on Colonsay Island off west-coast Scotland in 1995, referenced in Yates Beekeeping Study Notes (Modules 1, 2 & 3). “The bees had died out completely in 2–3 days after starting to collect nectar from Rhododendron blossoms (Rhododendron thomsonii) caused by the poison andromedotoxin or acetylandromedol.” Ted Hooper writes on the case of Colonsay Island’s bees: The West of Scotland College of Agriculture Study showed that the poison andromedotoxin was involved”.

It sounds like rhododendrons are not a desirable source of forage for bees! However, to put the risk of honey poisoning from rhododendron, or any other toxic plant, into perspective, I asked John Robertson of The Poison Garden website: “Put simply, something has to go wrong for toxic honey to be produced and then it has to go wrong again for it to cause human poisoning.” OK, so what can go wrong?

“The first thing that has to go wrong is to have a lack of species diversity. Generally, bees visit so many different plants that they don’t get a concentration of any particular toxin. This can go wrong, as in the west of Scotland, where Rhododendrons are almost the only thing in flower early in the spring. But, nectar from Rhododendron is toxic enough to kill the bees so they tend not to return it to the hive. Experienced beekeepers know not to let their bees out at this time of year. I haven’t seen any reports of poisoning from honey made from Rhododendrons.” John writes more on The poison garden blog, entry for Tuesday 27 September 2011.

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Image: Coriaria arborea | Rudolph89 via CC BY-SA 3.0.

Both John and Henry brought my attention to honey from the tutu tree (Coriaria arborea) in New Zealand, which could cause harm to humans, but this is due to the unusual way in which the honey is produced by insects. John says:

“Bees collecting nectar directly from the plant do not produce poisonous honey. But, a vine hopper insect also feeds on the nectar of the plant and excretes a sweet ‘honeydew’ containing a high concentration of plant toxins. Especially in times of drought, bees may gather this honeydew rather than nectar from the plants. Because this is a well-known problem, however, there have been no instances of poisoning from commercially produced honey since 1974. When four people were taken ill in 2008, the source was traced to honey produced by an amateur who was not aware of the problem. Another instance of the flaw in the belief that the more ‘natural’ something is the better it is for you.” Read more on The poison garden blog, entry for Thursday 30 June 2011.

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Image: Drone fly (Eristalis tenax) – not a bee! – on ragwort flowers | Francis Franklin via CC BY-SA 3.0.

Rhododendron is not the only mischievous plant in the garden. Yates lists common ragwort (Senecio jacobaea) in its section on unpalatable honey as “an injurious weed in the Weeds Act 1959, is poisonous to cattle and horses causing damage to the liver with pyrrolizidine alkaloids“. However, bees work the blossom for nectar and pollen with no ill effects to produce a bright yellow honey with an unpleasant smell.

What other mutinous plants, then, produce nectar and pollen that is harmful to the bee?

Ranunculus_macro

Image: Ranunculus macro | Laura Brolis via CC BY-SA 3.0.

The innocent-looking buttercup that pops-up in spring has bitter tasting leaves from a toxin called protoanemonin present in the sap. In 1944 in Switzerland, spring dwindling, or ‘May disease’, occurred after bees brought home pollen from the Ranunculaceae family (buttercup): “Nurse bees appeared at hive entrances trembling and unable to fly, excitedly moving on the landing board, losing control of their legs, rotating violently on their backs, becoming paralysed and dying. The leaves of most species of buttercup are poisonous and avoided by livestock” (Yates).

As the reference to this case is old, I dug deeper for something more recent. I found a study in the journal Functional Ecology, published by Wiley-Blackwell, which showed the contradictory effects of buttercup pollen and viper’s bugloss pollen in two closely-related species of mason bees: “While the larvae of Osmia cornuta were able to develop on viper’s bugloss pollen, more than 90% died within days on buttercup pollen. Amazingly, the situation was exactly the opposite with the larvae of Osmia bicornis” (Science Daily press release). The researchers suggested that some flowering plants used chemical defenses to prevent all their pollen being used by the bees to feed their larvae, rather than to pollinate the flower.

Abies_alba_Schleus_Berg_b_Suhl_ThW_Th_Dreger

Image: Abies alba Schleus Berg | Thomas Dreger, Suhl via CC BY-SA 3.0.

In 1951 another account of bee poisoning was reported in Switzerland, this time from the silver fir (Abies alba), which is a source of honeydew toxic to bees. “Thousands of returning foragers, with a waxy black appearance, were reported dying outside hives.” It was thought that sap-sucking insects feeding on the silver fir had converted the plant sap into sugars toxic to the bees (Yates). I was unable to find a more recently reported incident of silver fir honeydew poisoning in bees, although I came across a website that said silver fir honeydew honey is an “excellent table honey that goes well with cheese”. Is Abies alba still foraged for honey? If anyone has further information, I’d be interested to know.

In California, the pretty blossom of the buckeye chestnut tree (Aesculus californica) wickedly beckons bees to feed from its nectar and pollen: “The bees become black and shiny, trembling and paralysed. Non-laying queens, dying brood and infertile eggs have also been reported. As this species covers 14 million acres in North America its effects on honeybees are well known to local beekeepers” (Yates). You can read more about the buckeye chestnut tree and the honeybee in this interesting article by the University of California’s Bug Squad.

Then there is the mountain laurel (Kalmia latifolia), native to eastern US, introduced to Europe as an ornamental plant, and toxic to bees, humans and livestock due to the presence of andromedotoxin which could accumulate in the honey (Yates). However, the honey is reportedly so bitter that it’s unlikely to be eaten and cause poisoning (Wikipedia).

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All in all, it seems you’re more likely to come across a ‘poison honey’ in an episode of Poirot than find it on your breakfast table. John comments that the taste and texture of ‘bad’ honey, such as from common ragwort which “is waxy and unpleasant”, is probably enough to prevent anyone from eating too much of it. That, then, puts the lid on a fascinating topic.

With thanks to
A huge thanks to Dr Henry Oakeley and John Robertson for generously sharing their vast knowledge of plant lore for this post. If you’re interested in reading more about poison gardens or exotic plants, check out the links in the reading list below.

EDIT 19.01.15: And if you enjoyed reading my post, thank you. I’ll be making some edits to the information given here in due course in light of further information.

Further reading
A tour of the medicinal garden of the Royal College of Physicians by Dr Henry Oakeley, published by RCP
A year in the Medicinal Garden of the Royal College of Physicians by Dr Henry Oakeley, published by RCP
Rhododendron yakushimanum ‘Grumpy’ from RCP Medicinal Garden online plant database by Dr Henry Oakeley
The Poison Garden website posts by John Robertson from Thursday 30 June 2011 and Tuesday 27 September 2011
Toxic honey entry in Wikipedia
Collins Beekeeper’s Bible by Philip Et Al Mccabe, published by HarperCollins
A Guide to Bees & Honey by Ted Hooper MBE, published by Northern Bee Books
Yates Beekeeping Study Notes (Modules 1, 2 & 3) by JD & BD Yates, published by BBNO | (Yates recommends further details on undesirable nectars can be found in Honey Bee Pests, Predators and Diseases by RA Morse and R Nowogrodski, published by Cornell University)
Honey and Dust: Travels in search of sweetness by Piers Moore Ede, published by Bloomsbury
Claudio Sedivy, Andreas Müller, Silvia Dorn. Closely related pollen generalist bees differ in their ability to develop on the same pollen diet: evidence for physiological adaptations to digest pollen. Functional Ecology, 2011; DOI:10.1111/j.1365-2435.2010.01828.x | sourced via Science Daily press release.
• University of California’s post on buckeye chestnut tree and the honeybee from the Bug Squad
Mad honey poisoning‐related asystole from US National Library of Medicine | National Institutes of Health
• Emily Scott of Adventuresinbeeland’s Blog has written a brilliant post on 1st Honey bee products and forage revision post: a list of floral sources of unpalatable honey;

Further winter studies for bees can be found in my blog index.