A solitary bee quartet

I had so many wild things this summery sunny day that if was hard to settle for an invertebrate group to feature. For lunch I went out with fellow wildlife-lovers Robert Jaques and Callum MacGregor, and tried to capture some hoverflies. Hoverflies were indeed a good candidate for my wild group today as there were plenty, and of many species. Many males were hovering, but a couple of Myathropa florea males managed to sit on my hand, Robert's shoulder and Callums head and avoid the insect net altogether. Episyrphus balteatus, the marmalade fly, were also hovering, and the beautifully metallic Epistrophe eligans. Then I spotted a new spider, with a caterpillar on its web, and then another, would I feature spiders? Then a Red Mason bee started feeding on Buttercups, maybe a wild solitary bee day?

Female Red Mason bee, Osmia bicornis on buttercups. One of her 'horns' is visible at the front of her head. She uses its horns to mould mud she uses to seal her nest.

 Later after work I popped in for ten minutes in the wildlife garden. It was quite warm at the time. A leaf-cutter bee was feeding on thyme, and then chives. Its white and golden mittens flashed as it fed, a Willoughby's leaf cutter bee. Definitely a solitary bee day!

Male Willoughby Leaf-cutter bee, one of the easiest to identify by its front legs, which are covered on white-golden hairs in the shape of mittens, just visible here.

Back home I went to the sage. I had seen a favourite bee of mine yesterday very briefly. Anthophora furcata, a male which didn't settle, patrolling around the sage and the hedge woundwort. This is a rich brown bee with a very long tongue. Males have a yellow face and they have a strong preference for hedge woundwort, but also like several others flowers with deep corollas. Males appear, as many other bees, earlier in the season, settle in an area with their favourite flowers and check other bees, often head-butting them, while in search of females. And there he was, lovely and fresh. He even stopped the frantic patrolling to settle on a sage leaf to bask for a while, its back and face covered on pollen.

A male Anthophora furcata.

As I watched the A. furcata, a smaller bee caught my attention. It was a female Osmia caerulescens. This is a long tongued bee too, females have a bluish tinge and white hairs on stripes on its abdomen. After feeding on the sage, the bee stopped and stretched its tongue several times.

Female Osmia caerulescens

A female Osmia bicornis in the garden on the wallflower Erysimum 'Bowles mauve'.

If you'd like to learn to identify solitary bees, the Bees, Wasps and Ants Recording Society is a wonderful resource. Identification sheets for common solitary bees, often found in gardens are available too. There are 205 species, many hard to identify, but a few common ones are easy to identify once you become familiar with them.

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.

Bee hotel guests

Bee hotels are very popular at the moment. Most garden centres sell them, and they are advertised as homes for solitary bees. Solitary bees do use these bee hotels to make their nests, but once you get guests, how to tell them apart?
I was inspired to write this post after a twitter exchange starting with this message:

There appear to be about 225 species of solitary bee - think id unlikely!!! But so pleased something is using bee box :)
— Ragged Robin (@CarolineIrwin3) July 13, 2013

 With this post, I hope to give you an overview of what species of bees are likely to use bee hotels. In fact, only a small number of the over 250 species of solitary bees in the UK are likely to use bee hotels, so, with a bit of patience, identification is likely. For a start, not all solitary bees use bee hotels as they do not nest in cavities. Many solitary bees nest in the soil (the mining bees), others prefer the mortar of walls, or dig their nests in dead wood, or prefer much smaller holes or crevices than those provided in commercial bee hotels, which are usually made out of bamboo or reed canes. Mind, you, many more solitary bee species will be found in your garden than the ones that use the bee hotel. Once a female bee choses a tube in the bee hotel for nesting, you are likely to notice some activity, as she stocks the nest with nectar and pollen, lays eggs and builds partitions between the cells where her offspring will grow. Once she runs out of space in one tube she makes a stout plug and may start to fill another tube with more cells. The males searching for females or patrolling the area of the bee hotel can also bee noticeable.
 In addition to bees, other insects like some digger wasps or the cuckoo bees or flies that parasitise the bees themselves or spiders will also be seen on or near the bee hotel. My experience is on the north of England, and with home made bee hotels made by drilling holes in pieces of wood, so it is likely a few more species will be found to use bee hotels in the south.
 For identification purposes, time of the year, general size of the bee (use a honeybee as a guide) and colour patterns are useful. Also, it is very helpful if you can check what the bees are carrying as nest materials and the colour of the brush of hairs under the bees' abdomen that they use to carry pollen. The material of the plug covering the finished nests can also provide information as to what species built it. Once you can recognise the species or species group of the bees using your hotel, they are bound to provide an endless source of fascination, and bee watching may be addictive, so make sure you place your bee hotel in a spot you can easily and comfortably watch at close quarters!

Red Mason Bees
These are likely to be the first bees in spring using a bee hotel and the most likely species to use bee hotels. The bees are active from March to May. The females are reddish, with large, black heads, and size similar to honeybees. They have characteristic 'horns' on their faces, which they use to mould mud (above). Males are also reddish, smaller and with a white moustache. Males often sit on or near the bee hotel, sunbathing and looking for females.
  Mason bees use mud to partition cells in the bee hotel holes. They will travel from the bee hotel to the edge of ponds where they fetch mud, a little pellet at a time. Click here for more posts on Red Mason Bees in BugBlog.

Blue Mason Bees
These are much smaller bees and there are two similar species, Osmia leaiana and Osmia caerulescens (the blue mason bee proper). Males of both species are metallic green. They like to sit on the nest or stones or leaves at low level to sunbathe and from there they do patrolling flights in search of females. The females are metallic dark blue with a dark pollen brush underneath (O. caerulescens) or dark brown with an orange pollen rush (O. leaiana, above). Both species use chewed leaves to partition their cells.

Leaf-Cutter Bees
These are high summer bees, flying from mid May to August. I have two species in the garden, a large one and a small one. There are other common species in the UK, so care should be taken with identification. The male of the large species, Megachile willughbiella, is easier to identify, as it sports white-golden mittens on its front legs, which are very visible as he sits on the nest or sunny spots and grooms himself. Other identification features are the colour of the pollen brush on the underside of the abdomen: either orange (in the smaller species M. centuncularis, above) or red and black in M. willughiella (below). It is worth checking your bee hotel in poor weather, as these sun-loving bees like to use it as shelter in cold or wet conditions. More on leaf-cutter bees in BugBlog.

 Female Megachile willughbiella. Note the red and black brush of hairs under abdomen

Megachile willughbiella male. Note the pale 'mittens' on his front legs.

A few photos of the looks of the finished nests follows.

Two M. willughbiella males with two Osmia rufa (grey mortar looking) and a O. leaiana/caerulescens at the top, which is made of chewed leaves). 

A completed nest of a leaf cutter bee, Megachile. They use circular sections of leaves to make their nests.

Two recently completed nests of Osmia leaiana/caerulescens (I suspect the former, which in the last few days has been feeding on knapweed). Photo taken today.

The same area of the bee hotel on the 11th of May, just an Osmia rufa nest had been completed then.

Other bees that are known to use bee hotels in the UK are Chelostoma florisommne and Chelostoma campanularum, other Megachile species and Ectemnius digger wasps.

Ectemnius sp. a digger wasp, emerging from its nest.

More on Bee Hotels
Buglife.
Bees Wasps and Ants Recording Society.
Natural History Museum

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.

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.