by Philip Strange
The cloud melted away during the afternoon, allowing a little hazy sunshine to cast pale shadows and bring welcome warmth to this early spring day. The car park was nearly empty and I was standing, gazing at the grassy bank bordering one side of the parking area. I was watching the bees, taking the occasional photo and had become so absorbed that I hadn’t noticed the young woman sitting in a nearby car.
Her voice punctured my reverie: “Do you mind me asking what you are doing?”
She wasn’t aggressive, just inquisitive, but I still jumped.
“I’m looking at the bees that live in this bank”, I answered.
“Are they rare?” She continued.
“Not particularly, but I’m fascinated by them. There’s an amazing natural pageant going on here, all you need to do is look.”
I showed her some of the bees and the flowers inhabiting the bank and she eventually drove off. I hoped she hadn’t been too surprised or too bored by my impromptu lecture on the ecology of the car park.
It had all started when my friend Susan Taylor told me how in the previous spring she had seen some wild bees living in a grassy bank in one of the town centre car parks. I know the car park well, it’s called the Nursery and I can see it from our kitchen window across the narrow valley. I see dog-walkers crossing the area early in the morning as the sun is rising and, on busy market days, I watch drivers jostling for parking spaces. It’s a large rectangular space defined by old brick walls clad thickly with ominously-dark, green ivy. Along two sides of the rectangle, there are wide, sloping soil banks coated by rough grass kept short by irregular mowing. The grass canopy is interrupted by scars of bare friable soil together with a few old bricks, hinting at some previous use and there’s a scatter of litter decorating the area. I was intrigued to hear that wild bees had taken up residence in this semi-urban space and was determined to see them.
It’s easy for me to walk to the Nursery Car Park so, from late February, I made regular visits looking for the insects. Despite the perceptible lengthening of days, there wasn’t much to see at the beginning, just a few flies and the occasional bumblebee prospecting for a nest site. Then, one sunny morning in mid-March, I walked through the old brick arch into the car park and found the south-facing grassy bank bathed in gentle spring sunshine. Just above the rough grass, about half way along the bank, I saw for the first time a cloud of small bees. There were a hundred or more of the insects flying back and forth, swinging from side to side, mostly avoiding collisions, a wonderful sight. They reminded me of dust motes dancing in a shaft of sunlight only this was no passive display, there was real intention and energy expressed in their movement. Susan Taylor has christened this behaviour the “sun dance” and their activity does respond to the sunshine, becoming increasingly urgent on a hot day, like water simmering, threatening to boil over. Occasionally, insects left the dance briefly to investigate the rough holes in the underlying crumbly soil or to bask briefly in the sunshine. I thought I could see pale stripes on their abdomen but they were moving about so quickly it was difficult to be sure.
Then I noticed the flowers, dandelions and celandines, scattered about the bank pushing through the rough grass like shining signposts of the new season. Dandelions are so common we tend to undervalue them but their sunshine-yellow discs provide important insect forage early in the year as do the buttery-yellow stars of lesser celandine. Some of the bees were feeding from the flowers, drinking sugary nectar, their head buried in the flower’s centre, their body curved in a tight crescent. Now I could see that they were quite small, perhaps two thirds the size of a honeybee but clearly marked with thin buff-white lines around the black abdomen.
The unexpected beauty of these small creatures is properly revealed, however, in my photographs. The four abdominal stripes are, in fact, rings of short, pale hair. Dark brown hairs cover the top of the thorax, whereas the sides are coated with a ring of pale hairs. There is more pale hair on the face below the prominent black antennae and between the eyes. The legs are covered with fine hairs, yellow in some lights and often decorated with pollen particles.
Over the next few weeks, warmer days would find the bees “sun dancing”, but, when the temperature dropped, or rain threatened, they kept a low profile, sheltering in their burrows. By the end of March, however, I began to see another bee on the grassy bank. It looked very like the “sun dancers” only it was generally chunkier and, when I looked carefully, I could see thick orange hairs on their back legs, resembling a psychedelic bottle brush. Some of these larger bees disappeared into the rough holes that peppered the friable soil underneath the grass and began to dig so that soil cascaded downwards away from the hole leaving a slew of grey particles.
On a few occasions, one or more of the smaller bees leapt on one of the larger bees to form a small ball, triggering an explosion of frantic activity. Other small bees now rushed to join the throng. The growing ball of bees throbbed with nervous energy previously expressed in the “sun dance”. I realised that, within the melee, mating was occurring so that the smaller bees were males and the larger bees were females of the same species. At the core of the mating melee there is one female surrounded by several ardent male suitors only one of which will be successful in being her partner. With some delving in reference books I was now able to identify these bees as Yellow-legged Mining Bees (Andrena flavipes).
Once the females have mated, the males have fulfilled their role. They continued to “sun dance” on warmer days but over the next few weeks they gradually dwindled away. For the mated females, however, their busy time has only just begun. They now spend their days foraging on the increasing numbers of spring flowers, gathering nectar and pollen, often chrome-yellow at this time of year, symbolising for me the energy of spring sunshine.
Back at the grassy bank, I watched mated females returning to the holes in the friable soil with the bottle brush hairs on their back legs loaded with brightly coloured pollen. Upon arrival, they entered the hole, disappearing beneath the ground where the next phase of their life cycle continued. The hole is the gateway to tunnels 20 cm or longer that they have excavated beneath the ground. Each tunnel has several side arms which the female provisions with pollen and nectar before laying eggs.
The eggs grow into larvae which consume the food stores and eventually transform into mature bees ready for the next emergence of males and females. Although these bees make their nests in groups with many nest holes in the grassy bank, each mated female works on her own to produce her next litter of bees. Unlike the more familiar honeybees and bumblebees, there is no cooperation, no social group and these mining bees are referred to as solitary bees.
I saw pollen-loaded females returning to their burrows along the grassy bank well in to May, after which everything went quiet, or so I thought.
I wasn’t the only one to show a keen interest in these bees. One sunny morning in mid-April, I was watching the pollen-laden females returning to their burrows when I noticed two other insects paying special attention to the nests. I thought, at first, that one was a bumblebee. It was ovoid, about the right size and covered with rich tawny brown hair. When I looked closely, however, I saw that it was flying about the nest area with a very thin, straight proboscis extended in a most un-bumblebee like manner. This was a bee fly, out to take advantage of the mining bee nests to propagate its own species. When it spots a mining bee nest, the bee fly flicks one of its fertilised eggs towards the hole, like a footballer kicking at goal. These eggs develop into larvae which crawl into the bee nests where they devour the host larvae and take over.
The second, very different kind of insect was flying about the nest area in pairs or, sometimes, even in threes. These were wasp-like with black and yellow-striped abdomens; photographs showed that they had orange legs and antennae and one reddish-brown band around the abdomen along with the yellow ones. They swung about the nest area inquisitively, furtively, looking at the holes in the crumbly soil, occasionally entering. These are cuckoo bees and like their avian counterparts, they have no nest of their own, rather they lay eggs in host nests where their larvae use the food stores for their own development after consuming the host larvae. The cuckoo bee that colonises the Yellow-legged Mining Bee nests is called the Painted Nomad Bee (Nomada fucata).
These sorts of parasitic insects don’t sound like good news but, paradoxically, their presence shows that the host colony is strong. The parasites and their host can only coexist and prosper from year to year if the host is doing well. Despite its urban situation, the car park grassy bank provides a gentle, insecticide-free, south-facing environment with soft soil and protective brick walls. The area is surrounded by public and private gardens growing plenty of flowers so that the bee and its parasites can flourish.
High summer is a glorious time in the south west of the UK with warm sunshine, vivid colours and buzzing insects. I hadn’t seen the car park bees for several weeks and thought that they had finished for the year. One late June morning, however, I was passing the area and curiosity got the better of me; I decided to pop in to check the grassy bank and got a big surprise. It was a beautiful sunny start to the day; the air was filled with light and a palpable warmth arose to greet me from the south-facing soil bank. Just above the now longer and drier grass, I found a cloud of male Yellow-legged Mining Bees flying backwards and forwards and from side to side in their usual nervy manner. Another “sun dance” was in full swing, fired by the strong sunshine and expressing what I now realised was a pent-up sexual energy. It felt as though I had stumbled across a bunch of teenagers enjoying themselves.
The dandelions and celandines of spring were long gone but there was a dense stand of tall ragwort growing along another car park edge. The brilliant yellow flowers were providing a welcome feast for both male and female bees, their distinctive markings enhanced in this strong light. Another full life cycle was in progress and I saw pollen-laden females returning to their burrows to prepare nests for egg laying. These eggs will develop into larvae and eventually into new bees that will stay in the ground until next spring when they emerge and the cycle will begin again.
The Yellow-legged Mining Bee is one of several solitary bee species that produces two generations of new bees each year. Males and females of the spring generation emerge from their burrows in March having spent the winter underground. Their mating results in the second, summer generation that flies and mates in July to produce the overwintering bees. This kind of behaviour is possible only when the species starts flying early in the year and isn’t too choosy about the flowers it uses, but it does make these bees valuable pollinators.
This was a fascinating, magical spring and summer for me, spending time with the bees, watching them going about their lives. Each time I visited the car park to view this unique natural phenomenon, I found myself almost completely absorbed in the moment. Time stood still and my attention focussed on the bees to the exclusion of the world about me, except when a car manoeuvred nearby!
But there was more to my experience of watching these insects. The bees taught me to be aware of the seasons and the rhythms of nature. Of course, I had some idea of the seasons before but the bees taught me to look more carefully, to pay attention. They taught me to look at the flowers at different times of the year; the bees will come only when there are flowers to provide food. They also taught me to look at the weather from day to day and from month to month; the ability of the bees to fly is very dependent on weather conditions. Finally, they taught me that, when autumn beckoned and they had finished their cycles, it would all begin again the following spring.
Philip Strange is a writer, scientist and naturalist who lives in south Devon. He may be found searching for unusual plants on Chesil Beach, or looking for rare bees by the south west coast path, or chasing up a story about science in everyday life in the west country. Or you can look at his blog: philipstrange.wordpress.com