Bees toiling for nectar

Many flowers, closely protect their nectar in deep nectaries (e.g. the Mint family) or behind barriers made by modified petals, like pea flowers. This way, unspecialised nectar feeders, which may not be good pollinators such as ants might not be able to access the nectar, but bees, which will visit many flowers in succession and are effective pollinators will be able to. These modified flowers have their pollen-bearing anthers on the roof of the modified petal blocking the entrance. The bee, while coming in to feed on the nectar, rubs its back on the pollen, ensuring she will pollinate the next flower she visits. Bees, however, often have to work really hard to get at the nectar.
 A few days ago I watched a common carder bee, Bombus pascuorum, feeding on Iris flowers (top photo). It tried to get in through the side unsuccessfully, but eventually found the way in pushing through the middle of the landing petal (which are called 'falls').
Later, a female Osmia caerulescens, landed on a Phlomis flower, she seemed to sense there was nectar behind the hooded petal closing the flower and pushed with her head until it managed to get under it. It spend quite a long time inside, I guess this is a nectar-rich plant and it will take a while to empty the nectaries for a small bee like this.

Osmia caerulescens getting in.

The bee just before leaving the flower after feeding.

Cherry pollinators fest!

It was a warm, sunny afternoon and the cherry was at full bloom (three weeks earlier than last year), attracting a menagerie of bees, butterflies, queen wasps and flies. I did saw a honeybee, but I think even without this species, the cherry would be fully pollinated given the number and diversity of insects on it.

 Several bees were firsts for the year, including Bombus lapidarius, B. pascuorum and Melecta albifrons. I saw the first male red mining bee yesterday but they seemed to be everywhere today.

Bombus lapidarius queen 

Anthophora plumipes female

Queen wasp grooming

Possibly a dronefly

Male Osmia bicornis

and a Peacock also settled repeatedly on the blossom to feed

A small shining metallic wasp fell on the small pond and was rescued.

The first water beetle in the Victorian bath that makes our mini pond, awaiting ID.

Melecta albifrons, a cuckoo bee that parasitises A. plumipes, feeding on Muscari

 Melecta albifrons,  resting on a daffodil

And finally, a shot of a Red Mason Bee patrolling the Muscari.

A beesy beesy day

We've had a lovely, mild, quite sunny day today. Bees came out of their various hiding places and gorged on the garden flowers. Top bee magnets were the hardy geraniums and the hedge woundwort. At least one old Osmia rufa was still about, very late for this spring species. The first Anthophora furcata of the year turned up, at the usual time of the year. She fed on Hedge Woundwort (above, note how thick the bright red tail looks) and Iris. A male was also about.

Bombus pascuorum entering Iris.

 The only B. lapidarius I saw today

Osmia caerulescens female sunbathing

Competition for the hardy geranium, Bombus hypnorum and Osmia rufa

Osmia rufa leaving hardy geranium, note the visible 'horns'

Megachile centuncularis on Bird's foot trefoil

 Bee list

1. B. hypnorum hardy geraniums, cotoneaster. Males and Queens about.
2. B. pascuorum foxglove, purple toadflax, hedge woundwort.
3. B. hortorum foxglove, hedge woundwort, lamium maculatum
4. B. terrestris, Stachys byzantina, trying to feed on Lamium maculatum
5. B. lapidarius poppy, just one.
6. B. pratorum hardy geraniums, cotoneaster
7. Megachile willughbiella male on thyme, stachys
8. M. centuncularis birds foot trefoil, hardy geraniums
9. Anthophora furcata male patrolling, 1st female of yr., Teucrium, Iris, Hedge woundwort, Herb robert.
10. Osmia rufa, hardy geranium
11. O. caerulescens, sunbathing
12. Honeybee Philadelphus

Watching bees on foxgloves

June is peak Foxglove, Digitalis purpurea, season. This year, we have quite a few in the garden, and luckily one of them faces the conservatory, which allows me to observe visiting bees quite closely. Today I watched the bees feeding on it in sunny spells between showers. Foxgloves are said to be adapted to be pollinated by bumblebees: they have large, bell shaped flowers with a large landing lip and hairs that might deter smaller bees or other insects from entering. Indeed, bumblebees, and particularly long-tongue species, can reach the nectar deep inside the flower and actually pollinated it are the main visitors. A study in N Yorkshire found that Bombus hortorum (top, individual leaving flower with pollen load, and another individual just visible inside a lower flower) was the main visitor and preferred this flowers when available, but another study in Belgium found that B. pascuorum was the main visitor. The tree bee Bombus hypnorum is also a regular. All three species are commonly found on floxgloves flowers in my garden, with B. hortorum being the most common visitor. But other bumblebees, including those with short tongues do often collect pollen by 'buzzing' inside the flower even if they cannot reach the nectar.
 A few solitary bees also visit foxgloves. In my garden the forked tailed flower bee Anthophora furcata regularly visits them, and more rarely the carder bee Anthidium manicatum.
As relatively few species feed on this species, it is a good starting plant to familiarise yourself with bumblebees.
Today, I watched four bee species visiting this particular foxglove stem.

A male A. furcata (above) jumped on each visiting bumblebee to check them out, but was obviously feeding also on nectar. I haven't seen females around yet. The male has similar size and colour than a honeybee, but it has a bright yellow face and a visibly long tongue.

Bombus hortorum is the bumblebee with the longest tongue in the UK (above, with tongue extended). It can also be recognised by its double yellow band formed by the rear of the thorax and the front of the abdomen, and its white tail.

B. pascuorum is the most common all-brown bumblebee in gardens. 

Bombus hypnorum is a very distinctive bumblebee, three coloured: brown/black/white.

The stout black abdomen with lateral yellow patches of the Wood Carden Bee Anthidium manicatum which visited on 1/07/2011.

 Foxglove flowers open from the bottom of the stem towards the top. The plant reproductive parts are located on the roof of the flower, four stamens and a pistil in the middle, so that the body of a bumblebee entering the flower rubs against them. To reduce self-pollination, the flower anthers open first, delivering a pollen load onto bumblebees feeding. Five days later, when the pollen is likely to be exhausted the pistil becomes receptive, increasing the chances that it will be pollinated by the pollen of a different plant. I cut three flowers of a white foxglove in the garden and removed the roof of the flower to expose the reproductive organs. The one on the left, from the top of the flower spike just opened. The lobed yellowish sacs are the closed anthers, and the spike in the middle is the pistil, also closed and attached to the flower roof. The middle flower has open anthers and the pistil, although closed, has started to detach. On the left is the oldest flower from the bottom of the flower spike. Its anthers are almost devoid of pollen and the pistil is now pointing down, so that is easily rubbed by the bumblebee's back and then ready to be fertilised.

A bumblebee view of a foxglove. Note the open pistils on the lower, older flowers.

More information

Arthur A. D. Broadbent and Andrew F. G. Bourke (2012). The bumblebee Bombus hortorum is the main pollinating visitor to Digitalis purpurea (Common Foxglove) in a UK population. Journal of Pollination Ecology, 8 (7), 48-51.

Verboven, H., Brys, R., and Hermy, M. (2012). Sex in the city: Reproductive success of Digitalis purpurea in a gradient from urban to rural sites Landscape and Urban Planning, 106 (2), 158-164 DOI: 10.1016/j.landurbplan.2012.02.015

On the odd life cycle of bumblebees

I stopped by the comfrey patch this morning. The comfrey has now been in blossom for a good month. A Small White butterfly was feeding on comfrey, but I couldn't snap her. A ginger queen Bombus pascuorum fed on the blossom. A queen wasp got comfortable on a leaf and basked in the sun, as did some hoverflies. While I watched a couple of Anthophora plumipes males patrolling and feeding, a tiny worker of the tree bumblebee Bombus hypnorum, the first of the year, turned up (above). As I compared the sizes of these two bees – the bumblebee worker was smaller than A. plumipes - I reflected on the different life cycles of these two bee species. A. plumipes, a solitary bee, has males and females, while bumblebees, in addition of males and females (queens), have a worker caste. In bumblebees there are no males for most of the year: A male has a relatively short - if hectic - life. Upon emergence in the summer, he will find a queen and mate with her. The queen will store his sperm and use it to fertilise her eggs the following spring, when she will emerge from overwintering, build a nest and lay fertilised eggs, which will hatch into worker larvae. She will be busy collecting nectar and pollen from early flowering trees and plants to rear these larvae, and once the workers emerge, they will take over from the queen in collecting more nectar and pollen for subsequent eggs, although they won't reproduce themselves.  In the summer, the last batch of eggs of the queen will produce new queens and males, which the workers will help rear. Once they leave the nest, the founder queen and workers will die and the cycle starts again. Wasps, ants, bees, and bumblebees (hymenopterans) share a weird way to determine the sex of the offspring: fertilised eggs become females and unfertilised eggs become males: a system called haplodiploidy.

  Most sexual organisms have two sets of chromosomes: a set they inherit from their mother and another that comes from their father, but as bumblebees and other hymenopterans do not have a dad they just have a single set of chromosomes, the set coming from their mother.

How strange is that? If you think about it, the system means that bumblebee males don’t have dads, they also cannot have sons, only daughters, although they can have grandsons and have granddads. In addition, this arrangement causes strange relationships between the family members. We are equally related to our parents than to our kids – on average – but due to haplodiploidy, bumblebee sisters are more strongly related than they are to their mums. This is because full sisters have received an identical set of chromosomes from their dad, in addition to the set they receive from their mum, which is a mixture from the sets the queen received from her parents.

 This unbalanced genetic relationship between mother-daughters and sisters is thought to underlay the evolution of the worker caste, which do not reproduce, but help their mother to rear their own sisters.

The solitary bee Anthophora plumipes

A wasp? No, the exquisite wasp mimic hoverfly Myothropa florea

This is the real wasp. A queen common wasp 

Hoverfly Syrphus ribesii 

Another basking fly

A queen Bombus pascuorum

Late bumblebee collecting pollen

It is not unusual to see bumblebees in Autumn. Queens are still about, storing up some reserves before hibernation. What I found unusual is a worker of a Bombus pascuorum collecting pollen in my patch of Lamium maculatum today. The bumblebee visited each flower inserted its head deep into it and as exiting, wiped its furry back with its rear legs collecting the pollen on its corbicula or pollen basket. I understand that bumblebees collect pollen for their larvae, so there must be still be B. pascuorum active nests this late in the year.

The late bumblebee

A sign that the bee season is coming to an end when the only bumblebees visiting the lavender are carder bees Bombus pascuorum. There might be still a few queens of the other species around, but this handsome ginger carder bee is still in peak season, making use of the late summer flowers around. This bumblebee has a relatively large tongue (average of 8.5 mm) which allows it to use deep flowers, even foxgloves (above, a worker in mid June leaving a foxgloves against the dark background of my rubbish bin) and Iris, as food sources.
Other than in Lavender, at this time of year, they can be seen foraging on Verbena bonairensis, Sedum spectabile, Agapanthus, Sunflowers, Caryopteris, Cytisus, Buddleia, Nasturtium, hardy Geranium, Salvia, Honeysuckle and Purple toadflax.

Males (above) and queens appear at the end of the summer and the species can be seen actively flying until the first frosts. They nest on the ground and actively comb moss to insulate their nests. For a little video of a B. pascuorum nest click here.

Grape Hyacinth visitors

Many nectar-feeding insects prefer to use abundant floral resources. That is, a plant is much more frequently visited when there is a large clump of the species together or it flowers profusely, just because the insect has to travel less to obtain the same amount of energy. I have experienced this first hand in my garden with Grape Hyacinth (Muscari armeniacum) an early flowering bulb with clusters of deep blue flowers at the top of a spike. This year I have several large drifts of this species, which has been flowering for the last month or so and this has been rewarded by an unusually high diversity in the species visiting the flowers. Here is a selection of photos taken in the last few days on this plant.

Anthophora plumipes female loaded with yellow pollen and feeding on the flowers

Anthophora plumipes male, leaving the flowers with his tongue still extended

A male Red Mason Bee (Osmia rufa) sunbathing on a stone next to a Muscari clump. The first males of the year appeared today and I have watched them feeding and patrolling the plants, making sure they weren't missing any of the females. The males kept checking the Anthophoras.

A Peacock visiting the flowers. Grape hyacinths are also visited by Commas and Small Tortoiseshells (see here for photos)

This scruffy-looking dark bee with white tufts of hair is Melecta albifrons, the cleptoparasite bee (cuckoo bee) of Anthophora plumipes.

I have got no photos but a couple of days ago I saw an Andrena fulva and a queen Bombus pascuorum (both first of the year) visiting Muscari in my garden.

UPDATE 11/04/10

Today a queen Bombus terrestris visited the Muscari patch and I managed to get a shot of the first Osmia rufa of the year feeding on it as well.

UPDATE 17/04/10

A Green-Veined butterfly fed on the Muscari patch.

Fork-Tailed Flower Bee

There are not many UK bee species that can be readily identified based on a description. Anthophora furcata must be one of them. A few days ago I observed this bee feeding successively on Lithodora and Teucrium, both favourites of A. plumipes. My description on the day (10th June) was: 
New bee: Osmia rufa size, reddish, chestnut hair all over bee with yellow face and black antenna, long tongue.
I didn't have my camera with me - sometimes, I cannot do gardening and watching at the same time, only sometimes. A bit hopelessly I started a thread in Wild about Britain. In not even three hours after posting, I was surprised by an answer, Eucera (WAB Aculeate expert) suggested Anthophora furcata. After checking a few photos on Flickr, it became clear that this was the bee. Since then, I have spotted A. furcata on a a few occasions, so, it seems that is not a rare bee in Hull. So far, only males. Females are darker and with a reddish-orange 'tail' fringe. The species is present from early June to early August according to the Essex Field Club records - just two months! and specialises on Lamiaceae (mint family). It makes its nests by excavating tunnels in rotter wood. According to an excellent Solitary Bee site by Nigel Jones, the reason why they often go unnoticed is that they might be confused with the bumblebee Bombus pascuorum.
Today, I managed to get a few shots of a male feeding on a lovely patch of lavender, accompanied by Bombus pascuorum and B. terrestris.

A. furcata male, note how high his face is in the Lavender flower, this is due to the size of the tongue, it doesn't need to make an effort.

A different angle of the same male

The following is a shot of Bombus pascuorum for comparison. The yellow face is distinctive of male A. furcata. B. pascuorum always have black faces.