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A visitor from Eastern Europe and a winter hoverfly – Lockdown Nature Walks 12

For my next Lockdown Nature Walk I took advantage of a rain-free day to cross Totnes to look at some unusual flowers growing on the northern edge of the town.  Here is my account of the walk (taken on January 25th 2021) together with a poem by the American poet Ruby Archer entitled Fire in the Sky.  For my previous Lockdown Nature Walks, please click here.

The day dawned to a washed out, almost translucent, pale blue sky.  To the east, though, there was a hint of what was to come as an apricot halo crept above the low hills as if a fire were burning behind them. Then, as the sun rose, a raft of thin cloud towards the south east caught its light, first a rose-pink, then orange before relaxing to cream.  It was a good way to start the day.

No rain was forecast so I decided to walk across the town, past the castle to the northern edge, where semi-urban and residential gradually give way to rural.  It was a day of light and dark, a day of bright sunshine and long shadows, and a cold day where frost lingered in areas inaccessible to the sun.  

A minor road, Barracks Hill lies in this transitional zone, striking north away from the bypass past a modern housing development.  The road rises gradually between rough grassy banks and then more steeply to cross a low ridge.  This section of the road is enclosed and dark.   It rises, like a sunken green lane, between steep sides, some rocky, some covered in rough vegetation, emerging eventually into sunshine and open countryside with farmland and trees.  There was once a Barracks along this lane, built in the late 18th century.  Some of the buildings remain but most were demolished when a fine Georgian house was built in the 1820s.

But I want to go back down the hill to the lower part of the lane to look at the scruffy areas of vegetation that line the road.  Where it can, the sun casts pools of brightness on to these roadside banks, its spotlight picking out pennywort, hart’s tongue fern, brambles and what looks suspiciously like garden rubbish.  Whatever can get a foothold here seems to flourish and there is a long section of the bank where lime green, heart-shaped leaves push through a mass of dark brown, dry, decaying vegetation.  Unusually for the time of year, many sturdy flower spikes also rise above the leaves, some sporting striking blue flowers that sparkle in the sunshine like sapphire jewels. This is oriental borage (Trachystemon orientalis) commonly known as Abraham-Isaac-Jacob.  A relative of wild borage (Borago officinalis), this plant was introduced into gardens in the UK in 1868 from its native Bulgaria, Georgia and Turkey where all parts of the plant are consumed as a popular spring vegetable.

This patch of the plant is probably a garden throw-out and it seems very happy here, covered in flowers and having elbowed out all the competition.  At a first glance, the flowers look rather chaotic but this is because several different forms and colours exist together at the same time. 

First there are the pink tapering flower buds about 1cm long, decorated with a fuzz of white hairs resembling the stubble on an old man’s chin.   The buds open to reveal the strikingly beautiful complex flowers.  Each has five petals that curl and twist backwards creating an intensely blue frilly decoration around a crimped white collar reminiscent of a sapphire-coloured ruff around the neck of an Elizabethan lady.  Adding to the complexity, five stamens, each about 1 cm long, and a single slightly longer style protrude proudly from the collar as a tight cluster.  The stamens themselves are multicoloured starting white at the top, then pinkish-lilac, terminating as indigo anthers clasping lumps of pollen. 

As the flowers mature, they discard the petals and stamens leaving an odd-looking remnant where a spiky pinkish-lilac style emerges from hairy sepal cup.  This form in particular contributes to the overall messy look of the plant.    Unusually, all three flower forms, representing different stages of maturation, are present at the same time.  This may be the inspiration for the common name of the plant, Abraham-Isaac-Jacob, itself a reference to three generations of a biblical family.   [Photographs at the end of this post illustrate the three different flower forms.]

A plant that produces flowers at this low time of year is a rare discovery and these out of season sources of pollen and nectar often attract winter-active insects.  Nothing was about when I looked, though, and the day was probably too cold.  I came back a few days later on a warmer afternoon and was pleased to find a fine hoverfly on the flowers (see picture at the top of this post).  With its bulging brown eyes and distinctive barcoded abdominal pattern of yellow, silver and black bands this was a marmalade hoverfly (Episyrphus balteatus) a species that overwinters as an adult and emerges on mild winter days.  It was collecting pollen from the indigo-coloured anthers and nectar from the nectaries in the white collar.

…………………………………….

Fire in the Sky by Ruby Archer

I thought the darkness would not yield,
Glooming the sun-forgotten sky,
‘Till pulsing, surging glows revealed
A far-off burning,—home or field,
Up flung the light. Oh whence? O why?

I thought forgetfulness had spread
A Lethean gloom athwart one sky,
‘Till memory’s light crept warmly red
From flame I deemed in ashes dead.
Up leapt the light. Oh whence? Oh why?

…………………………………………………..

The roadside bank with the lime-green leaves and blue flowers of Abraham-Isaac-Jacob

Pink tapering flower buds with their decoration of white hairs

Three of the beautiful and complex flowers showing the frilly decoration of blue petals around the white collar and the tight cluster of stamens and style. Note also the indigo-coloured anthers with pollen.

Some of the spiky remnant flowers

Marmalade hoverfly (Episyrphus balteatus) feeding from the anthers of one of the flowers on Abraham-Isaac-Jacob

An experimental Bee House

Last year, I watched, fascinated, as Mason Bees (Osmia bicornis) made nests in tubes in a commercially produced Bug House situated in a local community garden, the Leechwell Garden. This Bug House is meant to be educational and so has been placed in a prominent position. This brings with it the risk that it will be subject to some attrition; indeed the removable tubes were tampered with both last summer and this spring and the Bug House was knocked off the wall twice during the winter.

I wanted to build another Bug House for the Leechwell Garden to be put in a less vulnerable place but it proved impossible to find a suitable position. I went ahead anyway and placed the new Bee House at the bottom of my garden which is about 100 metres from the Leechwell Garden (as the bee flies).

Experimental Bee House beginning of season
The Experimental Bee House at the beginning of the season (March 2015). I hope you can see the two vegetable boxes with the sides of the top one insulated with recycled vinyl floor covering, also the protective roof. Two cassettes with tubes are in place in the insulated top box . The garden still looks dormant although a few daffodils are visible.

 

My aim was that this experimental Bee House should be made from recycled materials so that it could be replicated by others at minimal cost. I looked around for suitable materials and one day as I was passing the Totnes shop of Riverford Organic, our local organic grower, I saw some vegetable boxes in the window. These looked ideal to make the body of the Bee House so I contacted them and they kindly gave me two boxes. The boxes were not fully sealed, needing insulation and rain protection, so I went to CarpetRight in Newton Abbot and they kindly gave me some samples of vinyl floor covering. I used these to insulate the sides of the new Bee House and to give it a roof. I found some logs, stones and bricks to provide ballast and stability as well as providing potential homes for insects. I sited the new Bee House so that it caught the early morning sun.

I wanted to provide tubes for the bees to nest in and had hoped to use inexpensive bamboo canes from the garden shop. Although I was able to cut up the canes, I found they were filled with soft material and unusable. I, therefore, had to buy solitary bee tubes from Wildlife World, my only outlay.

Experimental Bee House Cassette
One of the cassettes holding the bee tubes. The tubes are organised in to an old mineral water bottle and secured with a cable -tie. Four of the tubes contained mason bee nests from last year.

 

The tubes were organised in to cassettes. Each cassette was based on an old mineral water bottle cut down below its spout but long enough to protect the tubes. About 20 tubes were placed in to each cassette and these were secured using a cable-tie. I put out two cassettes in March, each containing four tubes with nests from last spring in order to give the new Bee House a start. A third cassette went out on May 28th when I thought the bees needed extra capacity but only two tubes were filled.

Experimental Bee House end of season
The end of season view. In two cassettes most of the tubes have been filled, in one cassette put out later two tubes were filled. Some tubes where the seal was broken have not been refilled.

After I had made the cassettes I read that plastic is a poor choice because it is not breathable but by that time it was too late to change design. Despite this, the new Bee House seemed to have functioned well and many of the tubes were filled by hard-working female bees during spring 2015. This is described in the previous post.

Successes and failures with this year’s Red Mason Bees

As we humans continue our lives and perhaps savour the prospect of settled warm weather and holidays, the busy part of the year is already over for the solitary Red Mason Bee (Osmia bicornis). These important pollinators began their activity in early spring and have now built their nests and laid their eggs.

Last year I was fascinated to watch some of these bees in a Bug House in the local community garden (The Leechwell Garden). This year I kept a closer eye on this colony to try to understand their behaviour. I also built an Experimental Bee House at the bottom of my South Devon garden and watched the bees build nests. [I realise not everyone is interested in constructing new bee houses so I have described this in the next post.]

This week is Pollinator Awareness Week so it is especially important that we think about how to protect and encourage these pollinating insects.

The males emerge and misbehave

male Osmia
Male Red Mason Bee

 

Both Bee houses contained mason bee nests (in removable tubes or in wooden blocks) constructed a year ago. The removable tube nests overwintered in my garden shed and were put out again on March 6; twenty four filled tubes and some empty ones went in the Leechwell Bug House and eight were put in the new Bee House. The wooden block nests stayed out all winter as they are an integral part of the Leechwell Bug House; they may have suffered damage when the Bug House was dislodged from the wall.

Osmia on Bug House
Male Red Mason Bee resting

 

I watched the tubes carefully from mid March and was very pleased to get the first hint that a male had emerged when, on April 16th, I noticed that one of the mud seals had been broken. The day before had been very warm so perhaps that encouraged the bees. Over the next week, I began to see males flying about near the two Bee Houses. Fresh males are very beautiful: about two thirds the size of a honeybee and with long antennae, they have vivid orange abdominal hairs, a fringe of beige hair around the thorax and a very distinctive pale “moustache”. Some look a bit different: they have few abdominal hairs and look rather shiny.

Osmia shiny type
Shiny type

 

Osmia feeding from Forget me Not
Male Red Mason Bee feeding on forget me nots

 

The numbers gradually increased over the next two weeks and on sunny days there would be a cloud of male bees near the Leechwell Bug House (perhaps as many as 30) behaving in a very characteristic way. They would fly about, swinging from side to side rather like a metronome, sometimes stopping to look in to a tube, sometimes flying off to feed on nectar. They would also “bomb” one another, especially another male that had stopped to rest or to warm up. I saw one male try to pull another out of a tube and, once his friend was out, he tried, rather unhelpfully, to mate. The cloud of bees would work themselves in to a frenzy when it was very sunny or when a male/female mating pair was present, perhaps they could they smell other females.

Osmia looking out
It’s too cold for me ……

 

All this activity would stop when the temperature fell to 11oC or lower. The males would retire to the tubes in the Bee House, sometimes two or more in one tube where they would look outwards waiting until the conditions improved. Other bees such as the Hairy Footed Flower Bee continued to forage at this temperature and the disparity may have something to do with size, the larger insect being able to tolerate the lower temperature.

Some females and some mating

mating pair April 28 15 2
Mating pair with mites

 

Mating pair with other bees May 7 15
The stillness of the mating pair and the frenzy of the other males.

 

I didn’t witness any females emerging from their nests but I knew that had happened when I saw mating pairs on April 28th and May 7th in the Leechwell Garden. This was an exciting moment as it was a first for me. I was amused to see the female in the first pair decide to go walkabout; the poor male had no option but to sit there even when dragged in to a hole smaller than comfortable for two bees. My excitement was tempered by noticing many mites on the first mating pair which I suspect is not good news for the bees. The latter mating pair did not have the mites as far as I could tell.

Males near the end

worn out bees

Some of the males continued to patrol the Bee houses up to a month after emerging, ever hopeful of finding a receptive female. By this time they were wizened and black and didn’t look like red mason bees any more apart from their white facial hairs. Perhaps we would also look sickly if we fed on sugar alone. They disappeared altogether by the end of May.

Hard working females

yellow pollen
The first pollen-loaded female.

 

May 12th was another exciting day as I saw chrome yellow pollen on the floor of the Bee House at the bottom of my garden for the first time: I now knew that the females were busy building nests. The females are also distinctive and very beautiful, about the same size as a honeybee and larger than the male with, on their head, two horns which they use for tamping down mud. They lack the pale “moustache” but like the males, their abdomen is clothed in vivid orange hairs when freshly emerged.

Female Osmia bicornis
Female red mason bee. The horns are just about visible.  Her colour has faded and a better view of a fresh female with her orange hair is seen in the mating pictures.

 

I watched the females returning after foraging, buzzing loudly and entering tubes head first. After a short time they reverse out, turn round and back in to the tube. I am not sure what is happening here but I witnessed the behaviour many times. Once this elaborate manoeuvre was complete they flew off for more. I also saw one female building a mud partition. She added mud to the inner surface of the tube and gradually, over several trips to collect mud, built the partition inwards keeping it symmetrical and circular before sealing it off.

Throughout the season, there seemed to be plenty of forage about and no shortage of mud for nest building. For both Bee Houses I saw females continuing to fill tubes in to the third week of June.

Problems

In both locations, the number of females seemed very low, especially as there were plenty of males. Last year most of the tubes and wooden block holes in the Leechwell Bug House were reused by females who cleaned out the mess before re-provisioning them. This year the females did reuse old tubes but seemed to prefer fresh tubes when available. In the Leechwell Bug House I saw only two females but they filled more than twenty tubes. Males emerged from the wooden block nests but none of these was reused. At the bottom of my garden there were at least four females and they filled twenty four tubes. In both locations, the mud seal on some of the tubes remained intact and neither males nor females appeared.

Osmia housekeeping
Housekeeping

 

End of season view
End of season for the tubes in the Leechwell Garden Bug House. Many are filled, a few have not been reused and a few have not been used at all.

 

I don’t know why this year has been less successful but I wonder if the tubes were tampered with at a critical time. I know that some were stolen last summer so I presume that, at that time, many of the tubes were disturbed. I also suspect that the tubes in the Leechwell Garden were tampered with again in March this year. Perhaps this double interference damaged the developing females. The Bug House also fell to the ground twice and perhaps the wooden block nests were damaged. Another possibility is that mated females were produced but decided to go elsewhere.

A third possible explanation would be that the old tubes had been infected with another organism that damaged the developing bees.

I opened up the wooden block nests to see if I could glean any information about these problems. None of these had been refilled this year, whereas last year they were all reused. The wooden blocks were very messy: I could see the individual cells made by the bees but there were no intact dead bees. The nests were filled with a brown dust although within this dust I could see dead larvae. It was also clear that in many cases the mud partitions between cells were still intact. There had clearly been a major problem with these nests and I suspect that they may have been infected. The bees avoided these nests so they seemed to know that something wasn’t right.

I am beginning to think that new tubes should be supplied each year to make life easier for the bees and to avoid build-up of contamination.

Now it’s important to leave this season’s nests so that the eggs can develop and grow in to larvae. I need to wait until late autumn before moving them.

Overview of the year

It’s been another fascinating season of Mason Bee watching and as before I have been enormously impressed by the hard work and ingenuity of these bees, especially the females. The males have only one purpose but they seem to do it well.

Watching these bees is not only a fascinating experience, it also makes you aware of the interconnectedness of the natural world. The bees depend on flowers and the flowers depend on bees. We mess with these relationships at our peril and perhaps we understand our own place in the world by realising this. The highlight of season for me was seeing the chrome yellow pollen for the first time. It signified that everything was working; females had mated and were visiting flowers to continue their species. Fresh yellow pollen has a colour like no other, it seems to glow with the energy of sunlight and signifies the unfolding spring.

We see our first Ivy Bees!

We picked our way carefully down the steep, stony path to the beach at Mansands, one of the many small coves dotted along the South Devon Coast. At this time of year, the banks lining the path celebrate the season with silky draperies of “Old man’s beard” punctuated by bonfire-sparks of red rose hips and great outbursts of flowering ivy. Pale sunshine coaxed a sickly sweet perfume from the ivy flowers and encouraged a busy profusion of wasps, hoverflies and honeybees but we were hoping to spot another kind of insect. Suddenly my attention was grabbed by a different shape and there it was: marginally longer than a honeybee, its abdomen slender and pointed with clearly defined regular stripes of black and yellow. This sleek insect was an Ivy Bee (Colletes hederae), with a fringe of russet hairs around the thorax and its manner of browsing the ivy flowers in a crescent shape. We saw a few more but they were elusive and moved about quickly. It didn’t matter, we had seen our first Ivy Bees!

Ivy bee on ivy

Ivy bee on ivy flower

I was pretty sure that if there were Ivy Bees about, there must also be nests nearby but the conundrum was how to find them. At other sites in Devon, the nests are said to be near the beach so that seemed a good place to start the search. Ivy Bees generally choose soft friable soils to build the tunnels that form their nests. The beach at Mansands is book-ended by south-facing cliffs containing buff-coloured sandy soil, some shale and some rock. Scrubby grass provides cover in places. This is probably an ideal environment for these bees and, when I looked, I saw many small holes pock-marking the cliffs. Numerous bees were buzzing around and based on their patterning and shape these were probably Ivy Bees. Rather like commuters at a busy rush-hour railway station, some bees were going in and out of the holes and some were moving about, occasionally colliding with others. The nests were distributed along a stretch of cliff about 50 metres wide; there must be thousands of bees here. It seemed too easy but, almost by accident, I had stumbled across a massive Ivy Bee settlement, a truly impressive natural phenomenon.

Detail of Mansands cliffs with ivy bee nests
Close-up of the nest area

 

Mansands cliffs with Ivy Bee nests
Cliffs to the north-east of Mansands. Much of this area is populated by Ivy Bees

When I looked more closely, I noticed that the female bees returning to their nests carried chrome-yellow pollen along their legs, looking as if they were wearing bright yellow lycra cycling shorts. They mostly disappeared in to the holes presumably to unload the pollen to provide food for their larvae. A few returning females rested on blades of grass before entering their nests. As they cleaned themselves, they were bombarded by other bees. These may have been hopeful males but the females showed no interest at all, having probably already mated.

Ivy bee with pollen
Ivy Bee with pollen

 

Ivy bee approaching nest
Competition!

 

Ivy bee resting on grass blade
Female resting before finding her nest

 

Ivy bee at nest
Having a look

 

The Ivy Bee is a relative newcomer to the UK having been first identified on mainland Britain in Dorset in 2001. Since then it has colonised many sites along the south coast and is also spreading north. It is the last solitary bee to emerge, flying between early September and early November. It shows a strong preference for pollen and nectar from ivy although it will feed from other sources. Some call it a mining bee as it digs tunnels for its nests but others refer to it as a plasterer bee from its habit of lining the nest with a protective cellophane-like coating. Although it is a solitary bee in that it does not form cooperative colonies, many Ivy Bees tend to nest in the same area.

There are two other solitary bees that are on the wing around this time and which could be confused with Ivy Bees. The sea aster mining bee (Colletes halophilus) looks very similar but it is confined to salt marshland on the East and South East coasts of the UK. Another look-alike is Colletes succinctus but this is a bee of heather moorland. The Mansands bees are unlikely to be either of these species, especially as there are large banks of ivy in the area.

These Colletes hederae are the last solitary bees I shall see until next spring and I can’t help marvelling at their behaviour. Ivy Bees spend a frantic period of roughly eight weeks on the wing when they have to mate and build nests. They must also lay eggs and provide them with supplies of pollen and nectar, helping to pollinate the ivy along the way. During the next ten months the miraculous transformation of egg to larva to pupa to bee occurs but we don’t see any evidence of this until the new bees emerge next year and the cycle starts again.

We visited Mansands on October 3rd 2014;  the photos were taken by Hazel Strange.

I should like to thank Amelia, who writes two fascinating blogs: A French Garden and Bees in a French Garden, for kindling my interest in solitary bees.