A new bee hotel and its guests

This year I got a new bee hotel, kindly given to me by George Pilkington from Nurturing Nature. What a great present! His bee hotel design has removable wooden sides with glass covering the actual grooves in the wood, so that you can remove the wooden sides and inspect the cells as they are being built, a rare peek into this usually hidden world. It is designed to provide suitable nesting holes for the common Red Mason Bee, Osmia rufa, which would naturally would use holes in masonry or cracks on walls to nest.
  I treated the nest with teak oil before hanging it out in early February (above). The Red Mason Bees took to it quite quickly after their appearance in the garden, and on the 11 of April the first female Red Mason Bee Osmia rufa roosted in one of the holes.

Below, a male here inspecting the hotel (14/04/14)

By the 10th of May the topmost hole had been sealed and the second had a couple of cells already made.

a poor photo showing the row of cells containing a mound of pollen, nectar and an egg laid atop. Each cell has a mud wall separating if from the following one (10/05/14).

Once a hole has been filled with cells the bee puts the final wall to cover the nest. This is the first finished row of cells.

On the 12th of May, I spotted the first beautifully fresh and golden Male Osmia caerulescens, sitting on the conservatory window by the sage. The males have been about about a week now, and females a couple of days. Males are very similar to Osmia leaiana males, but O. caerulescens have a strong preference for sage and hedge woundwort in my garden, while leaiana prefers knapweed.

...and the same day this very old, faded and bald male Osmia rufa  guarding the bee hotel.

A cleptoparasite fly Cacoxenus indagator is also present often around the bee hotel. This little fly, related to fruit flies, parasitises Red Mason Bee nests. The fly will lay eggs on the cell as a bee is provisioning it. Its grubs will feed on it, preventing the development and emergence of the bee (17/0514).

This female Osmia rufa is finishing filling the second hole.

On the 17th of May I also noticed a new bee (so I thought!). It turned to be a wasp, Sapyga quinquepunctata, which is a cleptoparasite of solitary bees including from the genus Osmia, the mason bees. I found this wasp on the nest and surrounding area. It has blue-purplish wings and white spotted abdomen, with curved antennae. Thank you to Ian Beavis who identified it from one of my photos on Twitter.

Another view of the wasp, on the post holding the nest. The wasp is also a cleptoparasite of Osmia and related bees.

The bee hotel today. Four cells have been completed.

Not only the bee hotel makes it easier to observe mason bees, but other bees and their cleptoparasites will also be attracted to it, increasing the chances of observing their development in the nest and interactions. Also to note that a spider, possibly Clubiona sp, has made a home in one of the holes.
Undoubtedly, I will post more on future developments on this bee hotel.

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

Pair of red Mason Bees

While I was gardening, a furry, buzzing ball drops from the sky into the bottom of a clay pot full of broken crocks. I peek in: it is a pair of Red Mason Bees and the female, with the male firmly holding onto her back, has trouble climbing out. I give them a helping hand and place them on a dandelion. The female quickly starts to feed, greedily on the nectar. The male keeps holding on. He vibrates his wings making an audible buzz, drums with his antennae, kicks her abdomen and pushes with his head against the female's head. I know that Red Mason Bees do mate guarding, a behaviour by which the male 'piggy-backs' onto the female after mating to prevent her to be inseminated by a different male, allowing his sperm valuable time to fertilise the female's eggs. I have no way of knowing if they had already mated at the bottom of the pot, but the male's behaviour was far from a passive 'guarding': he was very busy indeed and oblivious to the food nearby. He carried on for a few more minutes and then flew away. The female fed for a while longer.
 You can watch a short clip here:

Red Mason bee male checking out Melecta

A Melecta albifrons male has been feeding lazily on the Erysimum in the afternoon a sunny day.  Clambering over the flowers, not bothering to fly, this cleptoparasitic bee behaves in a very different way to its host: the buzzing, hovering, always alert Anthophora plumipes. Red Mason bee (Osmia rufa) males are patrolling the flowers and they check everything vaguely looking like a Red Mason bee female. With their contact, they scare away females A. plumipes - which I guess feel harassed like they do when their own males jump on them. A male Osmia rufa sees the Melecta and jumps on it. Just a quick contact, presumably chemical cues are checked and if not right, the bee flies away. The Melecta stays on. And when I check the camera, I am thrilled I got the shot!

Melecta albifrons male (photos 26/03/2012). They are handsome bees.

Solitary bees are back!

In the last week I have been spotting more and more species of solitary bees around. First on scene, as usual, at the beginning of March, Anthophora plumipes, the Hairy Footed Flower bee. Then, a couple of days ago I saw the first Andrena fulva (Tawny mining bee) and yesterday I saw a couple of unidentified Andrena sp. (below). Today the garden was buzzing with at least 4 males A. plumipes, and a female feeding on Erysimum, and the cast was complete when in the afternoon a male Osmia rufa (Red Mining Bee) turned up and stopped to bask on the wooden frame of the conservatory (above). All of them have broken records as to how early they have appeared in the year compared to my previous records, which is not surprising given how mild this winter has been. From a few days to a few weeks before previous years, just as many flowers are also blooming early. The Red Mason Bees breed in our bee hotel, but we have been making another one from reclaimed floorboards and canes, I will push to finish it this weekend as females won't take long to appear.
 Are your bees early too?

Andrena sp.

Another Andrena enjoying a Dandelion

The new bee hotel in construction

Bees in ponds

When you think about a pond, bees do not normally spring to mind. Bees, however, need water. In sunny days honeybees travel in numbers to water sources to take water to cool down their hive, and they also use it to dilute honey to feed their larvae. These three were drinking by the edge of the pond in my local wildlife garden, near their hive.

On the other side of the pond edge there is a muddy site. Several female Red Mason Bees (above) were collecting mud to line and cap their cells. A female would dig up the mud and shape it with the  help of her jaws and two little facial horns into a little ball, and then fly to the nest holding the ball in her jaws. It took me a few attempts to get a half decent shot.

Osmia rufa female with her ball of mud

Tree bees. 1. Holly.

These days I am looking up trying to find bees in trees. Insect pollinated trees can attract large numbers of bees, as they offer a highly concentrated resource: hundreds or thousands of flowers are present in the same spot. The drawback for the bee watcher is that, unless you carry binoculars, identification is not easy. There are two holly trees in my garden and I had noticed patrolling Red mining bees and feeding Bombus hypnorum in them before, but I could not take good shots. Today I found a holly hedge in bloom and I could get close to the bees that pollinate this tree. Holly flowers are small and inconspicuous and I have rarely noticed bees visiting them, but this little bush had many bees in it. Hollies are dioecious, which means that there are male and female trees, self-pollination is not possible and fertilisation requires insects visiting first a male tree and then a female tree. I am not sure if male holly flowers produce nectar as well as pollen. On the photo above a male Red Mining bee sits on the flowers of a male holly, its antennae covered on pollen.
In their Holly monograph, G. F. Peterken and P. S. Lloyd stated:

Entomophilous. Apis mellifera L. is the commonest insect visitor, but the following bees have been observed in southern England (O. W. Richards): Andrena wilkella Kby. (Andrenidae), Osmia rufa L. (Megachilidae) and Bombus lucorum L. (Apidae). B. lucorum and syrphid flies have been seen at the flowers in northern England. Nectar is secreted from tissue at the base of the ovary.

A honeybee visiting the flowers.

An Red Mining bee at the left of the flowers with scopa full of yellow holly pollen

Reference:

Peterken, G., & Lloyd, P. (1967). Ilex Aquifolium L. The Journal of Ecology, 55 (3) DOI: 10.2307/2258429

Rowan Feast

During the short period of time each season that a plant or tree is in full bloom they become a magnet for bees. This is the case of the rowan in the garden these days. Its flat, white inflorescences offer a white background for photos, but in many cases they are too high for close shots. Bees will pollinate many trees - for example holly and horse chestnut - but observation is even more difficult. The first Bombus hypnorum workers of the year were collecting pollen in our tree. Other bumblebee like B. lapidarius, B. pratorum and B. pascuorum will also forage on this tree. Many Red Mason Bees and a collection of hoverflies also feasted on the rowan today. Above, Helophilus pendulus, the footballer hoverfly.

This female Red Mason bee about to land on the flowers is showing its pollen basket under her abdomen and the little "horns" on her face that help her collect mud and make her nest partitions.

A Bombus hypnorum worker with a heavy pollen load.

Melecta, a cleptoparasitic bee

The plum tree started flowering last week and today it was buzzing with bees. I counted six species, Bombus terrestris and lapidarius queens, Anthophora plumipes males and females, Andrena fulva, with males actively patrolling the branches, and the first males Osmia rufa of the year. Later, a black bee with white and grey hair patches and dark wings turned up. It was Melecta albifrons, a cleptoparasite of A. plumipes. I haven't found much information on M. albifrons so the following life history account mainly comes from a study on the American species, Melecta separata. Melecta females parasitise Anthophora species that nest communally. They explore their host's nesting aggregations in search of finished nests. A female, upon finding a nest will start digging and breaking open the sealed entrance. Then she will lay an egg on the roof of the cell, seal the cell and replug the nest. Anthophora females usually attack the cuckoo bee, but she either flies away or if inside the nest it defends herself with her sting. The Melecta larva hatches a day earlier than the Anthophora's and is very mobile. They pierce and drain the Anthophora egg and any other Melecta eggs that she finds in the cell with their long sickle-shaped mandibles. Only one Melecta larvae survives, as if two are born at the same time one will kill the other. The larvae then feeds on the syrupy mixture of pollen and nectar intended for the Anthophora larvae. Subsequent larval stages lack the long mandibles of the first stage. The following year a Melecta will emerge from the cell, having consumed the food intended for Anthophora grubs. In a M. separata nesting aggregation 20% of the nests were parasitized.
The Melecta albifrons visiting my plum showed a very different behaviour from other bees, sluggish, like she didn't want to fly too much, climbing over the flowers to reach each of them and feeding showing a very long tongue. The bee stayed for quite a while feeding on the plum flowers. M. albifrons has a very similar distribution to its host in Britain (click here for distribution map), reaching up to the Yorkshire Wolds in the north. Its peak flight period is a few weeks after the emergence of the host, and flies from April to early June. Given that it doesn't need to collect pollen for provisioning its brood, the bee is not fussy about what flowers to visit, and tends to fly at short daily periods - the warmest - as they are less endothermic than their Anthophora hosts, as shown in the figure below.

References
Thorp, R. (1969). Ecology and Behavior of Melecta separata callura (Hymenoptera: Anthophoridae). American Midland Naturalist, 82 (2) DOI: 10.2307/2423782
P. G. Willmer and G. N. Stone (2004). Behavioral, Ecological, and Physiological Determinants of the Activity Patterns of Bees. Advances in the Study of Behavior, 34 , 347-466 : doi:10.1016/S0065-3454(04)34009-X

Red Mason bee male tactics

I posted about the Red Mason Bees (Osmia rufa) nesting in our bee post last year. The males  have now been active for a few weeks, and they are quite interesting to watch, as they are very inquisitive and interactive with other insects. The different behaviours of male bees depend to some extent on how the resources used by females - such as nesting sites and food plants - are distributed. These resources indicate where females are to be found, and to maximise their reproduction males are to encounter and mate with as many recently emerged females as possible. In Osmia rufa, females are thought to mate only once shortly after emerging from their nest, as males guard females after mating and impregnate them with chemicals that make the females unattractive to other males, effectively ensuring their paternity. As many other bee species, Red Mason Bees are polylectic - they are quite generalistic as to what flower species they feed on - and their nests are quite scattered (at least in natural habitats!), and therefore it does not pay to be territorial. In a 1988 paper I read today, Karsten Seidelmann graphically described Red Mason Bee behaviour based on 364 individually marked males:

In order to find mates, each male roamed about his home range. These home ranges were located around flowering groups of foods plants, but also by nesting places. Occasionally sunny places (exposed leaves, stones, etc.) or bushes of dwarf pine in the surrounding of large nest aggregations were inspected and patrolled as well. Home ranges sometimes also consisted of several small patchy encounter sites. Males then searched within the patches and flew in a straight line between them. Every home range contained an exposed sunny place where the resident male basked between patrol flights at irregular intervals. When home ranges become shadowed, males turned to other areas, returning when the area was in the sun again. Areas abandoned because of shadows were not occupied by other males.


The photo heading this post shows a male next to a potential nesting hole in our bee post. The males often enter and inspect the holes and look out.
These little bees often chase and make contact with other bees - not only of their own species but also other insects such as butterflies in their home range - and I had misinterpreted this behaviour as agressive, an indication of territorial behaviour. Seidelman's detailed observations, on the contrary, shows that the Red Mason Bee is not territorial. It does have a 'home range' but these are not exclusive to one individual and home ranges of different males partially or totally overlap. Males also occasionally went on 'excursions' away of their home range. Their chasing and making contact with other visually detected insects is an 'inspection' behaviour: they check if they are conspecific females or not, but they do not attempt to drive them away:

Home ranges ranged from 3 to 30 m2 in size. Males continuously altered their home ranges in response to changes in possible encounter sites. Plants that started to flower were integrated in adjacent home ranges, or new home ranges were established and old ones were abandoned. If females emerged from a large aggregation of nests, the searching activities of several males were concentrated entirely on these nesting places, with males inspecting nest entrances frequently.
Males inspected all resting and flying insects with an O. rufa-like shape during their patrol flights. They approached other solitary bees (e.g., Osmia, Megachile, Anthophora, Andrena), as well as honeybees (Apis), bumblebees (Bombus), or even flies (e.g., Calliphora). However, only receptive females of their own species were mounted, whereas males of O. rufa and other insects were abandoned immediately after a short contact.


Seidelman also analysed the reproductive success of males, that is, how many times they mated throughout their lives and concluded that this is independent of the male body size.

More information at:
Karsten Seidelmann (1999) The Race for Females: The Mating System of the Red Mason Bee, Osmia rufa (L.) (Hymenoptera: Megachilidae). Journal of Insect Behavior, Vol. 12:13-25. here.

Robert John Paxton (2005) Male mating behaviour and mating systems of bees: an overview. Apidologie 36:145–156. here.

Making cherries

We've got a small cherry tree in our garden. In addition to making a spectacular show when it blooms, it produces the sweetest cherries and, although the crop can be a bit hit and miss depending on the spring weather, it is a bug magnet for a few months. The tree only started flowering a week ago but today was buzzing with bees. I spent some time this morning watching the blossom and trying to ID the bees that are feeding on it or visiting. Anthophora plumipes and Osmia rufa males have incorporated the tree into their patrolling routine, circling around the blooms, chasing other bees and keeping track of the females. Beautiful, velvety shiny red female Andrena fulva were also feeding on it as were female A. plumipes. I stopped counting the honeybees as there were quite a few. To the high pitched buzz of the Anthophora bees, the deep buzz of queen Bombus lapidarius and Bombus terrestris was added. These busy lot of creatures were involved, without realising it, in fertilising the blossom and contribute to making the cherries that hopefully we'll eat this summer.

Peacock butterfly

Bombus lapidarius

A full Andrena fulva sunbathing near the tree.

Outside the blooming season, which lasts a few weeks from April to May, the tree growing buds are covered on black aphids that in june produce a sweet sap, loved by bumblebees, especially Bombus terrestris and Bombus hypnorum. I have also seen Bombus pratorum feeding on the nectaries at the end of the leave stalks. Aphids also attract scores of ladybirds. The cherries themselves are prized by wasps - and birds.

Osmia rufa update

The new bee post has been a great source of both entertainment and frustration (lots of blurry shots of bees leaving nest!). Now females are very busy going in and out of the nests and we can follow live how each provisions the cells and finally blocks the nest entrance with dark mud. Today three cells had been finished. The bees feed all around the garden. They visit the apple blossom and the rosemary. A new development is that we have found the cleptoparasitic fly Cacoxenus indagator visiting the post - not yet entering nests. Not only have the bees been quick adopting the new bee post, but they have rapidly been followed by their parasites.

This is a selection of photos of the last couple of weeks.

A pair of Osmia rufa. Apparently, the male stays on top of the female for a while after mating. Note the smaller size of the male and the 'horns' on the face of the female

A bee about to leave the nest. It looks like a male

Another male inspecting a hole

Female starting to build the last cell wall

The wall is almost complete

The finishing touches

The finished nest

This little fly - same size and family than the fruit fly - is a cleptoparasite of Osmia rufa nests. It lays its eggs on the stored pollen in the cells.

Links: Solitary bees

Red Mason Bee

Osmia rufa for beginners

An article with interesting photo of the inside of the nest

Another article with lots of info on associated fauna to Osmia rufa nests