Lots of Life in the Churchyard

15th September 2013
There's a Warwickshire village churchyard about 15 minutes drive from where I live. It hosts (amongst other things), a very large colony of Yellow-legged Mining Bees (Andrena flavipes]. I guessed that activity in the colony would have ceased, but a week or so back I visited to see what else was around.

I haven't seen many Hylaeus Yellow-faced Bees this year, but there were a few at the churchyard. Hylaeus bees are generally small, black and hairless with yellow/white markings on the head, legs and thorax. These marking can be useful aids in identification, but species are very similar and difficult to differentiate from photographs. There are twelve different species of Hylaeus bee in Britain. This female (12 antennal segments), has collected a large droplet of nectar. Hylaeus females are unusual in that they have no pollen-collecting hairs. Pollen and nectar are collected and carried back to the nest site in their crops. This was a good start to the photography session!

On some stone slabs at the base of the church wall, I found my next bee. This is a female Halictus tumulorum. These small ground-nesting bees are common and widespread, but I've only seen one before. The females are characterised by having a conspicuous greeny/bronze colouration and pale abdominal hair bands. I recognised this one as soon as I saw it.

There are four species of Halictus bees in Britain. The females have pollen-collecting hairs on their hind legs. They often nest in aggregations and they may be solitary or social. More about this later!

I was pleased with what I had found so far, but could see lots of other interesting things around. There were several of these medium-sized bees feeding on the same plant as the Hylaeus bee. I didn't recognise this one. I guessed it was a male because of its slim build and longish antennae. Males bees have thirteen antennal segments. The legs were noticeably yellow and there were prominent, pale abdominal hair bands. There were also similarly-sized female bees on the flowers too and I guessed these were the same species. Later, I saw a small nesting aggregation of these bees near the base of the church wall.

I sent images of these bees to an entomologist friend of mine who identified them as Halictus rubicundus, sometimes known as the Yellow-legged Halictus. This was a "new" species for me. When reading up about them, I also discoved something else new. Halicus bees and other bees in the subfamily Halictinae, can be social or solitary. In my ignorance, I had thought that bumblebees and honeybees were the only social species and that all the 200+ other special were solitary. Broadly, social bee nests contain more than one generation at the same time and have a "division of labour" amongst females with some (queens) having a reproductive role and the others (workers) caring for offspring that are not their own. In solitary bees, females provision a nest, lay their eggs and then leave it; never seeing their offspring.

With Halictus tumulorum and Halictus rubicundus, both solitary and social nesting behaviour can occur (depending on circumstances), but sociality is the norm. (Some sources state that solitary nesting in these species occurs only rarely or not at all). Fascinating stuff!

Next to be found was this male Sphecodes bee. There are sixteen British Sphecodes bee species. Generally, they are smallish black bees with red markings on the abdomen. I guessed that this was one of those species but didn't know which. Again, lots of the species are very similar and need specialist knowledge or microscopic examination to differentiate.

It's been suggested to me that this could be Sphecodes gibbus. This would make sense because Sphecodes are cleptoparasitic "cuckoo" bees and this species is parasitic on the nests of Halictus rubicundus. Cuckoo bees do not construct their own nests. The females invade the completed nests of their host species, where they lay their own eggs. Sphecodes females sometimes remove the egg of the host bee but generally, this is eaten by the parasitic larva which then consumes the food stores.

Not only do bees like Halictus tumulorum and Halictus rubicundus have to put up with the unwanted attentions of cuckoo bees, they can also fall prey to predatory wasps. This is a female Cerceris rybyensis, the largest of the four British Cerceris species. They usually prefer sandy soils for the construction of their nests. This species provisions its nest with a variety of bees, commonly Halictus species. The female captures the bee and paralyses it with a sting. The paralysed bee is then carried back to the nest. The developing wasp larvae feeds of the paralysed bees.

Well, an interesting photographic session that yielded several species I hadn't seen before and which illustrated the complexities of some insect community interractions. There was also another very interesting predatory insect. But more of that in another post!

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