Harebell Carpenter Bees

Our native bees come in all shapes and sizes – from the uvuncular bumble bees to the sporty leafcutters and the tricksy nomads. One of my favourites is also one of the most inconspicuous – you may well have seen them around a garden campanula, mistaken them for small flies and thought no further. Whilst I’m not advocating flies as worthy of oversight, the harebell carpenter bee (Chelostoma campanularum) is certainly rewarding if you take the time to look a little closer.

Harebell Carpenter Bee - Chelostoma campanularum

These tiny black bees are just 6-7mm long and black all over. The females have a white scopa – as illustrated in this BWARS profile of the bees – and the males are very similar in size and appearance.

We have a number of campanula species which are native to the UK, including the harebell along with a range of bellflower species which are larger and more akin to the ornamental garden varieties, such as nettle-leaved bellflower. Fortunately, these little harebell carpenters don’t seem too fussy and I’ve watched them on two different ornamental cultivars in our garden over the past few years.

To watch these bees around the flowers, you might be forgiven for wondering what precisely they’re doing – they often look for all the world as though they love the flowers… but don’t know what to do about it. In fact, they are intimately intertwined with the genus – the females will only collect pollen from bellflowers and this blog from Urban Pollinators has some great images of their specialised means of collecting this. They also mate in the flowers and females will wait for males in the flowers, whilst the males will  swarm and circle around on the hunt for females! Males will often shelter in the flowers in dull weather too.

These bees are aerial nesters – this means that they will seek out opportunities such as dry stems and holes in wood to nest in. This makes providing for this species in your garden very straightforward – simply plant some campanulas (the native harebell is a delightful addition to any garden) and provide some bundles of reed or straw at height for them to nest in.

The bee is on the wing from June through to August and has a mostly southerly distribution in the UK but certainly occurs around Grantham in the midlands!

Below is a slow-motion video of the harebell carpenter bees in our garden flying around an ornamental bellflower – but if you want to see some excellent images of the bees at rest, check out Ed Phillips’ blog post here. And if you want the detailed image of males and females, as well as habitat shots, head over to Steven Falk’s flickr albums!

Harebell Carpenter Bee - Chelostoma campanularum

How to make a bee hotel

If you look carefully at who’s visiting your flowers in the spring and summer, you’ll soon spot a range of subtly different and equally beautiful bees alongside the industrious honeybees and the avuncular bumblebees. We have 250 species of ‘solitary bees’ in the UK – far more than the social species combined and a number of these can be encouraged to nest in your garden through provision of pollen, nectar and a place to stay!

Who can you expect to see?

A number of different species can be found using bee hotels. One of the most common, and most widely provided for, is the red mason bee. These rusty coloured bees, around the size of a honey bee, are on the wing from March to July and will readily take up residence in a well constructed bee hotel. The females visit ‘mud mines’ where they gather up balls of soft mud to line and seal the individual cells within the nest tubes. They are a welcome visitor to any garden, especially if you have fruit trees, as they are a prolific pollinator, estimated to be over a hundred times more efficent than the honey bee. A number of the other Osmia (mason bee) species are also likely to pay a visit if the conditions are right.

The photograph below shows a red mason bee feeding on green alkanet – a great source of early-season nectar for spring bees.

IMG_0063

As the year progresses, leafcutter bees emerge in the summer. These are so named for their habit of cutting circles of leaf from species such as roses which they use in a similar way to the mason bees – to line their nests and segregate the cells. A good garden can provide the leaves they need to line their nests; the nest tubes themselves; and a good source of pollen and nectar for the adult bees to feed on.

The photograph below shows a brown-footed leafcutter – Megachile versicolor – visiting our bee hotel last year with a section of leaf ready to line its nest.

Orange-vented leafcutter bee building its nest with rose leaf segments in our home-made Bee Hotel

Alongside the charismatic species such as bees, you might also get some less charming but equally intriguing species. Last year, one of the nest tubes in our bee hotel was used by a willow mason wasp who hunted and paralysed beetle larvae to bring back to its nest.

But a word of warning: don’t expect the hotel to be free of uninvited guests. The life history of bees is a complex one – they have ‘enemies’ including other bees (often named cuckoo bees), flies and wasps which will parasitise and exploit them. This is all part of the ecosystem which has developed and whilst you might feel protective towards your bees, you should bear in mind that the parasitic species is generally rarer than its prey!

The photograph below shows a wasp using its long ovipositor to inject its eggs into the nest tube of one of the solitary bees in our garden bee hotel.

IMG_3873

How to make a bee hotel

It’s worth bearing in mind before you begin, just what you are aiming to do in creating a bee hotel. The species who are most likely to be attracted to the hotel are those which nest in cavities naturally; these include dead plant stems, holes in decaying wood often bored by beetles, and holes in brickwork. What you are seeking to do is replicate and ideally perfect these conditions for your garden visitors.

Whilst there are many purpose-built boxes on the market these days, the nesting opportunities are easy to make yourself and understanding what you are tying to achieve can open up lots of opportunities to be creative. You could create the features within existing woodwork in your garden, say a fence post in a sunny spot or an old sleeper. Similarly you could create several small hotels of just the right size and shape to fit in with your existing materials in different locations around the garden. The additional advantage of multiple small hotels is that you are avoiding a dense congregation of nests, which may be more susceptible to parasites and ‘enemies’ and thereby maximise the chances of your bees successfully rearing broods.

Firstly: the materials.

You can use lots of different materials, but do remember that wood treated with chemicals may be harmful to bees so certainly avoid anything freshly treated. Offcuts of old wood can be good though, along with logs, bamboo canes and other similar materials. You need your materials to be a minimum of around 8 inches deep, but some variation can be fine.

Secondly: the structure.

We have had bees happily nesting in holes in fence posts where old screws have come out, but if you are making a bee hotel from scratch, you should aim to ward off any potential hazards. Aim to make your structure rain-proof – this often means constructing a simple box within which to place the nest tubes and put on a sloping roof which overlaps the top. This will allow the rain to drain off and keep the nest tubes dry. A box also helps to hold your tubes together and give them stability. I used a back board as well, which could be used to affix the different blocks of wood and keep the whole thing stable.

Thirdly: the nest tubes

One way to achieve the nest tubes is to use a drill and create various sized holes in the pieces of wood. These should be up-to 7 inches deep and vary in size between 2mm and 10mm. Different bee species like different sizes of holes, and producing a variety will maximise the chances of the hotel being used by a number of species. Larger holes, around 8mm, seem to be favoured by the leafcutter bees with smaller holes used by smaller mason bees and species such as the delightful harebell carpenter bee. It’s important to make the entrances to the holes smooth, by sanding or otherwise removing rough wood and splinters asd these could damage the wings of the bees.

Another option is to use bamboo canes cut to the correct lengths – again taking care to avoid splintered edges. A variety of different sizes will similarly work for a range of species.

Dead plant stems, especially those robust enough to maintain their structure such as hogweed, reed or nettle, can provide a ‘natural’ nest tube. These can be bundled together length-ways to create a tempting array of opportunities.

With the box illustrated below, I opted for a combination of all of these materials which creates a pleasing arrangement – an important consideration if you are going to site this somewhere prominantly in your garden – as well as providing a diverse range of nesting opportunities.

IMG_9313.JPG

Fourthly – the position

The bee hotel should be placed somewhere south facing, in full sun if possible. The key requirement is sun in the morning to allow the bees to warm up and start their day – like all invertebrates, they are cold blooded. You should also ensure that they are not shaded too much by vegetation, for the same reason.

The video below is a selectively-speeded clip, taken over 15 minutes in realtime, of bees emerging tentatively as the sun warms the bee hotel in the morning.

Finally – the management

Whilst you can fit and forget, many will advocate that an element of management is in the best interests of the bees to secure the long-term value of the bee hotel. Whilst parasites and enemies are a natural part of the bee’s life history, the creation of durable, artificial nesting habitat with higher densities of nests than would occur naturally can affect the balance of parasite and host and result in the bees failing to successfully hatch out a new generation.

I am no expert in this area and will defer to others for this advice. This website is a great resource for further and more detailed reading on how to make a bee hotel, and how to manage it. Some sources talk of bees vs. pests when discussing management and this is, to my mind, an unhelpful distinction. Where your provision of nest boxes is not significantly upsetting the balance between the bees and their parasites/predators, then the loss of some eggs and indeed some broods to species of parasitic wasp and flies which depend upon them for their own survival is entirely to be expected. A wild garden should have space for these as well as the bees – creating a habitat invites an ecosystem rather than a species in isolation. However creating a ‘sink’ for bees which are drawn to the nest box and then fail to raise a brood because of the density of paratises or the impacts of fungal attacks is not a desirable outcome. In this instance, the bees may have been better served by not creating the bee hotel in the first place. Cleaning out holes in wood; swapping bamboo tubes; and replacing dead stems is recommended by some, but you need to be careful in your timings and approach to ensure that your actions are not inadvertantly removing the eggs and larvae before they hatched.

One obvious way to minimise some of the risks would be the creation of multiple, small bee hotels around your garden if possible, as this addresses many of the density issues and reduces the risk of entire broods failing in a given year!

Find out more…

For more information about solitary bees – Ryan Clark has put together an excellent introduction to the species native to the UK in this Wildlife Trusts article. If you’re looking to identify solitary bees in your garden, this is a great place to start. If you begin to delve deeper, it won’t be long before you reach the work of Steve Falk who has produced the Field Guide to the Bees of Great Britain and Ireland – an indispensible book if you are looking to further your knowledge of our native species.

2017 in Invertebrates

Bees and butterflies have had a blog post to themselves, but here are a few other invertebrate encounters from 2017 I thought I’d share on the penultimate day of the year!

Wood Ants

These were taken in Great Wood in the Quantock Hills. We spent a while being amazed at the ability of these tiny creatures to pull twigs and other materials into position around their nests, joining others to give assistance where required or simply tugging with amazing tenacity until they got where they were going. Soon we also noticed the guard ants, who were trying their hardest to intimidate us into backing away and leaving the nest in peace!

IMG_9122

Great Diving Beetle – Dytiscus marginalis

We came across this beast when doing great crested newt surveys in the springtime – the bottle traps used to catch and count the courting newts also work for other species such as this, one of our largest beetles. They can have quite a nip, so I’m told, so this one was handled with care before being returned to its pond in a pasture field.

Great diving beetle - Dytiscus marginalis

Sawfly in a buttercup

I came across this little sawfly – its head dusted with pollen – settled in a buttercup flower in Muston Meadows in early summer. It didn’t move as I got into position to take a photo, and I could only assume it had settled there for the night.

Sawfly settled into a buttercup flower to spend the night

Wasp – Gasteruption jaculator

This amazing looking creature was feeding on the fool’s water cress flowering at the edge of our garden pond. The amazing ovipositor is so much larger than the wasp itself which made it look for all the world like a radio-controlled insect as it flew between flowers!

IMG_9791

Wasp – Ectemnius sp.

I came across this little wasp feeding on the hogweed flowers on a walk through Cheddar Gorge and thought it deserved a portrait – the rounded head with the eyes wrapped around looks as though it could have been the inspiration for a number of sci-fi aliens!

IMG_7422

Ornate-tailed digger wasp – Cerceris rybyensis

I was walking through the Hills and Hollows above Grantham one afternoon and came across a series of holes in the bare earth – I watched a while and saw several heads peeking out before one of the insects arrived from outside and I could get a proper view. This is a species of digger wasp whose prey is bees such as this solitary bee held beneath its body. The wasps bring the bees back and pull them underground to provide food for their larvae.

IMG_5355

Darter dragonfly – Sympetrum sp.

This dew-bejewelled dragonfly was resting on a flower stem in Muston Meadows in August. Taken just after sunrise, this shows the roosting behaviour where the dragonflies will find a safe place to spend the night, waiting for the sun to warm them in the morning and get them up to temperature so that they can take to the wing once more.

Snail

This little snail was crawling across the roof of my car when I got back from a dawn bat survey in late summer. I’m not sure how it made its way all the way there, but I liked the reflection in the early morning sunshine. I popped it back into the vegetation in the verge before heading home!

Wolf spider (Lycosidae)

This photograph was taken in the Grantham Hills and Hollows in late summer as the grasses were beginning to turn from greens to browns. I had bent down low to get a photograph of one of the wildflowers, and then my eye was caught by how many invertebrates were active just in the grasses beside it.

IMG_1953

Grasshopper

This grasshopper was taken on the same afternoon as the wolf spider above – I’m afraid I haven’t attempted an ID on this little character but would welcome any suggestions! The camouflage of this grasshopper amongst the greens and browns of the aging summer grassland meant I only spotted it when it hopped to another location.

IMG_2050

Minotaur beetle – Typhaeus typhoeus

This amazing beetle was trundling across a forest path in the Quantocks in autumn. Despite the fearsome looking horns, they are not predatory but are in fact a species of dung beetle which feeds on rabbit droppings amongst others. They nest in deep tunnels and will pull the dung back down with their powerful legs in order to provision the larvae.

 

 

 

 

Boisterous Wool Carder Bees

This summer, I discovered a colony of wool carder bees in the Sensory Garden beside the River Witham and these characterful little creatures became the focus of my lunchtime walks for much of the rest of the season. The photographs and slow-motion videos below were all taken in this garden over the course of the summer.

IMG_9686.jpg
Wool carder bee feeding on lamb’s ear

The wool carder is a striking bee – chunky and robust with sporty yellow markings down the sides of the abdomen which is tipped with five spikes in the males. They are in the megachile family – alongside the leafcutters – but are the only representative of the Anthidium genus to be found in the UK. More broadly, they are one of the 250 or so solitary bee species in the UK. They are common in England and Wales but are just starting to make their appearance into Scotland.

The name ‘wool carder’ is an intriguing one which relates to an even more intriguing behaviour. ‘Carding’ is a mechanical process which involves disentangling, cleaning and preparing fibres for processing, and the word originally comes from the latin ‘carduus’ relating to teasels or thistles which were historically purposed for the task. In this context, ‘wool carder’ relates to the behaviour of the female bees who shave plant hairs and fibres from leaves and stems. They gather these fibres into a bundle and take them to their nest site – often aerial holes and crevices as well as hollow plant stems and bee hotels – and use them to line the nesting tubes.

28351030974_2152754fab_o
Male wool carder bee resting on the ‘wool’ of a lamb’s ear leaf

The wool carder bees forage on a range of species, specialising in those in the deadnettle and pea families such as betony, woundwort, mint, balm, loosestrife, toadflax and restharrow. This study from Kernowecology found that in native vegetation, marsh woundwort and purple toadflax were the most commonly used flowers for nectaring whilst greater bird’s foot trefoil was most commonly used as a pollen source. They advise that planting those two species together is successful in attracting these bees.

However many people will encounter the bees, as I did, on a garden plant and Stachys byzantina seems to be one of the most popular for this species. This plant is one of the woundworts which is a member of the deadnettle family which the bees favour for nectaring, whilst also having perfect ‘wool’ for the females to gather for their nest tubes – the plant is not known as ‘lambs ear’ for nothing! This combination of the bees’ two key requirements makes them irresistible to the female bees and this is something which the male bees take advantage of.

The male bees are larger than the females, and are highly territorial. I spent many lunchtimes watching them patrol a patch of lamb’s ear, waiting for the females to arrive. Once a female landed to nectar, the male would pounce upon her for a swift and unambiguous mating – see video below – before leaving the slightly startled looking female to continue visiting the flowers.

The males would regularly rest in a spot of sunshine before upping and patrolling the flowers in search of females or rivals.Interestingly, one might expect the male bees to limit their attentions to other male wool carders who represent a direct rival, but instead they will attack and chase away any other bees including honey bees and much larger bumblebees – see videos below. This is thought to be a mechanism of maximising the value of their territory, and thus making the plant more enticing to female bees. They will grapple with these other bees and pull them off the flowers and sometimes pursue them to the ground. The spikes in the base of the thorax are then seen to be not simply for show – the male wool carders use these aggressively, capturing their enemy between their curled thorax and the spines in order to inflict damage.

This behaviour is fascinating to watch, and seemed of little concern in the garden as the wool carder males limited their attention to their patch of lamb’s ear, leaving other bees safe to forage on the multitude of other flowers nearby. However this aggressive behaviour gives significant cause for concern when the bee is invasive in other countries such as the US and New Zealand. Their distribution close to ports in NZ indicates that they may have come across in ships, whilst they have been detected in various parts of the USA since 1963 and are making an appearance across the country, establishing now in western USA. Kelsey Graham is studying the effects of the wool carder as an exotic species on the native US bee populations. As in the UK, there is considerable concern in the USA about the decline of native bees including bumblebees and other solitary bees species such as the Osmia. The impacts of the exotic wool carder bees in the US relate in part to competition for nectar as they are sharing a finite resource with the native species, but particularly relate to the aggressive behaviour of the males in attacking the native species. Kelsey identifies that the chemical changes induced in the plants by the ‘carding’ of the females releases chemical signals which attract further wool carder bees. Native US bumblebees seem most likely to be attacked, and Kelsey’s research has found that this leads to these bees avoiding areas where the wool carder bees patrol, thus reducing the availability of foraging resource to the native bees. You can read more about Kelsey’s research here.

The wool carders are a summer bee, flying from June – August, and visiting the Sensory Garden in September seems somewhat lacking without the antics of this boisterous and charismatic bee. Kate Bradbury wrote a wonderful piece in the Guardian about watching these bees in her newly created wildlife garden where they arrived in less than a year, so I am hoping that the already-established lamb’s ear in the garden of the house we have just moved to will provide this spectacle on our doorstep next summer!

28865297682_733a7f93c1_o.jpg
Wool carder bee in flight

Bee is for beginnings…

It is incredible what you find, when you start to look. There is a certain sloe which grows along the River Witham in Grantham, and for some reason it seems to beat every other blackthorn to bloom. I was walking along in March and saw a bumblebee visiting the flowers. It turned out to be a tree bumblebee – the first species I could name beyond ‘bumble’. Throughout the summer, I have added new bumblebees to my acquaintance as well as many other characters which together make up the family bee. I have very much more to learn and look forward to doing for many years to come, but I was amazed at just how much I have never noticed before. I have gone all these years and yet never seen mining bees visiting the garden, or the nomad bees lurking near their nests. I have never watched mason bees collecting mud or realised that they have their tunnels in the walls of our house. Tiny, beautiful solitary bees and huge queen bumblebees, leafcutters and honey bees and that’s before we even get on to all the pretenders; the hoverflies and beeflies which imitate and exploit! I have illustrated below just a few of those I have been lucky enough to see this year, I hope it might inspire you to explore for yourself.

Bumblebees

Early in the year, the queens emerge from hibernation and feast on the early flowering plants; the heathers and hellebores were a favourite in the garden whilst long-season gorse flowers are an ideal early-spring feed in the wild. These queens will establish nests and then the whole process of ID becomes more complicated as the workers and males appear – similar but subtly different to the queens of the species. There are 24 species in the UK but around six are the most commonly encountered; the Bumblebee Conservation website is a fantastic resource to get you started and with a few key ID tips, you are well on your way with most species!

The first bumblebee I tried to ID - the tree bumblebee (Bombus hypnorum)
The first bumblebee I tried to ID – the tree bumblebee (Bombus hypnorum)
A queen garden bumblebee (Bombus hortorum)
A queen garden bumblebee (Bombus hortorum)

Mining bees

These bees are so named because they dig holes in the ground in which to lay their eggs. There are around 100 species in the UK and they include some exquisitely beautiful specimens such as the tawny mining bee which is a stunning shade of autumnal red. The ashy mining bee and early mining bee also paid a visit to my garden this year. In contrast to the bumblebees, they are largely solitary although some species do nest communally.

A tawny mining bee (Andrena fulva) photographed along the Grantham Canal
A tawny mining bee (Andrena fulva) photographed along the Grantham Canal
An early mining bee (Andrena haemorrhoa) photographed in my garden
An early mining bee (Andrena haemorrhoa) photographed in my garden
An ashy mining bee (Andrena cineria) visiting a hogweed flower along Grantham Canal
An ashy mining bee (Andrena cineria) visiting a hogweed flower along Grantham Canal

Nomad bees

These small bees are not immediately obvious to identify as such on first glance – they are rather more wasp-like than bee-like. There are around 30 different species and they parasitise the nests of other bees – especially mining bees – laying their eggs in the nests which gives rise to the alternative name of ‘cuckoo bee’. There are also cuckoo bumblebees which behave in a similar manner with the nests of bumblebees although I have not (yet) managed to spot one of these.

A nomad bee on gorse flowers at the Hills and Hollows in Grantham
A nomad bee on gorse flowers at the Hills and Hollows in Grantham

Mason bees

There are several species of mason bees in the UK – these are so called because they use mud when constructing their nest. We have red mason bees nesting in holes in the pointing of our house but many different crevices and cavities can be used. The bees lay their eggs inside the tube structures and then seal the end with mud. I came across a ‘mud mine’ down beside the River Witham in Grantham where mason bees were coming and going collecting mud, with up to 10 present at any time. The hollows you can see in the photograph were excavated by these bees which gather up the mud and fly back to their nesting sites with it clutched between their mandibles.

A red mason bee (Osmia rufa) gathering mud from the bank of the River Witham in Grantham
A red mason bee (Osmia rufa) gathering mud from the bank of the River Witham in Grantham

Leafcutter Bees

These bees have a similar ecology to the mason bees, only they use leaves instead of mud as their medium of choice when sealing up their entrances. I spotted this one in our back garden but was lucky enough to watch one ferrying segments of rose leaf from a nearby bush to a bee-hotel in my parents garden. The semi-circular cuts around the edge of the leaf are quite distinctive when you’ve seen them once and a sure sign that these bees are around.

A leafcutter bee resting on a plantpot in my back garden
A leafcutter bee resting on a plantpot in my back garden

Solitary bees

There are a large number of small solitary bees which are often difficult to identify as they are so small and subtly different. This one was identified for me as a male Lasioglossum calceatum, probably the commonest of this particular genus in the UK.

A male Lasioglossum calceatum solitary bee on a burdock flower - distance is relative!
A male Lasioglossum calceatum solitary bee on a burdock flower – distance is relative!

Honey bees

There is only one honey bee species in the UK and it is quite distinct from the rest. Whilst the patterns may vary, the shape and general demeanor make them quite distinctive. Many honey bees belong to hives but wild populations also exist and you can see them from the first spring sunshine through to the last throes of summer.

Honey bee (Apis mellifera) leaving a Himalayan balsam flower
Honey bee (Apis mellifera) leaving a Himalayan balsam flower

The active season for many invertebrates, including the bees, is coming to an end. Common carder bumblebees are still around in good numbers but it won’t be long until they too vanish from the flowers. I am already looking forward to next spring when the queens emerge from their hibernation and there will be a new host of commonplace marvels to notice for the first time. The sheer diversity is breathtaking – it only requires you to bend a little closer to the ground to take it in. I would cordially invite you to do so!

Common carder bumblebee (Bombus pascuorum) feeding at a fumitory flower
Common carder bumblebee (Bombus pascuorum) feeding at a fumitory flower