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July 2020: wildlife, from the Somerset Levels

July 29th 2020. I had another go at searching the log-flats. It is important to keep checking activity, in what should be one of the busy periods of the year. But it was so hot that nothing much was going on. I have noticed this before, when there is strong sunshine on the logs at lunchtime, the insects put back their activity to later on in the afternoon; though it goes against the saying that insects thrive on the heat of the day. Then I noticed a strange-looking mason bee. It is now categorised as a lesser mason bee. It is smaller than the various Osmia mason bees and has a cream-coloured pollen-basket beneath her abdomen. After some checking, it became clear it was Hoplitis claviventris.

lesser mason bee Hoplitis claviventris f

There was a very strange nest closure over a hole in a nearby log and wondered if it was from this same bee? 


lesser mason bee closure Hoplitis claviventris

I have come across H. claviventris before, both out in the wild and once on the logs, but that was ages ago. Nearby, I noticed a wolf-spider Lycosidae on a leaf, consuming a wasp. It loomed over the poor creature and must have been terrifying in close-up.


Wolf spider, Lycosidae

July 21st 2020. I found out that Westhay Moor NNR was now open and decided to see what it was like after such a long time. I drove up to the Lake hide turning and parked by the side of the drove. Lazy maybe, but I am not sure I could walk up all that way and still be able to get to the interesting part and the reserve itself. I think I have earned it after all these years. It was virtually empty, a family on bicycles and a couple on a circular walk. I took a macro set-up with me and concentrated for a change on searching the surrounding undergrowth for insect life. It was just as well I had not brought the long lens, bird life was all but absent, apprt from swans and one Great white egret Egretta alba in the distance. I was more succesful with insects, though there was little variety, and smaller numbers, but the peaceful, familiar surrounds were a delight after so long an absence. The majority of insects were bumblebees, busy among the herbage. I saw only three species; Bombus terrestris, by far the most numerous, B. pratorum, tiny and very active, and a very few B. pascuorum.

bumblebee Bombus pascuorum m

bumblebee Bombus pascuorum m

bumblebee Bombus pascuorum m

bumblebee Bombus pratorum m

bumblebee Bombus pratorum m

bumblebee Bombus pratorum f

The most unexpected find was what I believe to be the social wasp, Dolichovespula media. It had the trade-mark yellow reversed-7 on the side of the thorax, but no black bar on the clypeus, just a minute dark dot.

social wasp Dolichovespula media

Among all the herbage there were a few butterflies. Like many of the insects, they were feeding on Lesser burdock Arctium minus. The most beautiful of these was the Peacock.

Peacock Inachis io

Finally, to my delight, there were numbers of Black-tailed skimmers settling just ahead on the path, before lifting at the last moment - a true sign of our wetland summers.

black-tailed skimmer Orthetrum cancellatum m

It was really good to be back walking the reserve, even if it was not the sunniest of days. The reeds looked so fresh, the wind blew over them and the trees were still in varying shades of green.

I received an e-mail from John Mason the other day that I believe ought to be included here. Thank you John.

'I was interested to read your account of leaf cutter activity on your website diary pages. I have had some leaf cutters visiting my logs recently and like you, noticed how they seal the hole with a token leaf fragment that falls off easily. It is an untidy piece of leaf not cut to either of the two precise shapes used in making normal cells. I don't know why they do this but it must signal something.
I have long taken a botanical interest in leaf cutter activity and have collected many examples of leaves cut by the bees, involving some twenty different species of plants. In our garden in North London leaf cutters almost always used Rose Rosa sp. leaves, but occasionally they cut Tutsan Hypericum androsaemum leaves. Since then I have found that they can use the leaves of many trees, shrubs and herbaceous plants. There is no obvious basis for their choice. I used to assume they chose leaves such as Rose because of their strong texture but the use of floppy leaves such as Dandelion Taraxacum officinale and Black Bryony Tamus communis, which have barely any texture at all, suggests that texture is not a key factor. What is fairly obvious is that once a type of leaf has been chosen the bees keep returning to it over and over again. This was dramatically demonstrated by a small cherry tree Prunus avium on Shapwick Moor in September 2018 where virtually every leaf had been cut by leaf cutters.
I attach some scans of leaves cut by bees. The Wisteria leaves are typical examples that show clearly the shapes cut by the bees. The Montbretia 1 scan shows a couple of brown cut leaf fragments that are still attached because the bees failed to cut the last thread of tissue. Montbretia 2 shows several places where bees have started to cut pieces but have aborted the attempt when they encountered the strong midrib of the leaf.
I have saved some leaf cutter cells from previous years and in section (see attached picture) it is possible to see that multiple layers of leaf pieces have been used both for the sides and for the ends, so no wonder they need so many pieces of leaf.'

Montbretia 1 Crocosmia X crocosmiiflora © John Mason
Montbretia 2 Crocosmia X crocosmiiflora © John Mason

Tutsan Hypericum androsaemum © John Mason

Wisteria Wisteria sinensis © John Mason

July 19th 2020. I had a most enjoyable walk at Loxley Wood, apparently the only person there. It was rather late, so I saw few insects with a couple of interesting exceptions. One of the more unusual hoverflies, Xylota saylvarum, was present, although only the one. This often solitary species is distinguished by a patch of really golden hairs at the back, on the side of the abdomen. It is always good to catch a glimple of one of these. Once again, the bumblebee mimic Volucella pellucens was to be found on the few white flowers.

hoverfly Xylota sylvarum m

hoverfly Volucella pellucens

Surprisingly, among a few butterflies, Silver-washed fritillaries were still flying.

Silver-washed fritillary Argynnis paphia

July 16th 2020. The flats were visited by one or two rather mysterious little black digger wasps this morning. I am still not completely satisfied which they were. One had widely-separated antennae when viewed from near above, the complete opposite to Crossocerus megacephalus which always appears as if the two antennae arise from the same point - it is a matter of how they bend and angle. This feature does not fit any of my normal visitors but has finally been pinned down to Psenulus and Mimumesa as possibilities, both are black diggers that nest in wood. Another view showed an extraordinarrily long head. This may of course be an unusual angle, but it looks quite different to what I have seen before. I will continue investigations and bring my conclusions back to this entry. (After studying various books and many pictures, I am convinced now that it is a Psenulus spp). This has been spotted here prevously, but only very occasionally.


digger wasp Psenulus spp.


digger wasp Psenulus spp.

Much easier to identify was one of my favourite little digger wasps, somehow always neat and jaunty. A rather nice 'transparent' picture that shows the insect's structure.


digger wasp Pemphredon lugubris

The last picture was of one of those tiny little parasitic wasps, with very long ovipositor, that visits the flats regularly in search of suitable hosts.


parasitic wasp Gasteruption jaculator f

July 12th  2020. A visit to the flats produced an unexpected happening. Earlier in this season, I photographed a male Megachile willughbiella, instantly recognisable by its flattened and hairy front legs. Up to now all the female leafcutters have been M. versicolor, but this morning the females were all M.willughbiella, identified by chestnut hairs on the thorax and triangular final abdominal segment.

leafcutter bee Megachile willughbiella f

leafcutter bee Megachile willughbiella f

leafcutter bee Megachile willughbiella f 

Everything was moving the whole time, one bee seen shooting into a hole, another flying in search of an unoccupied potential nest, others flying in with large sections of leaf beneath their bodies, jutitng out behind and in front. While I have seen M. willughbiella in the past on certain flowers, I have not come across them at the flats. Now here they were in numbers - fascinating. Another notable insect weas a Coelioxys, darting from hole to hole searching for a host nest. They are beautiful insects, the females unusual in shape, with long pointed abdomens, cuckoos on certain solitary bees found in the flats. It was difficult to determine whether this one was C. inermis, preying on M. centuncularis and M. versicolor, or C. elongata on M.willoughbiella. Both species have been found here. From the timing, and the fact that C. inermis is the most frequent over the years, I feel she is most likely to be of the latter species.

cuckoo bee Coelioxys inermis f

cuckoo bee Coelioxys inermis f

Another brilliantly-coloured wasp turned out to be one I have not come across before in the flats, always an exciting moment. She was another Ectemnius, this time the larger M. cephalotes, with a partially yellow scutellum.

digger wasp Ectemnius cephalotes f

Finally, I noticed, and photographed, several tiny chalcids. Pteromalus apum is parasitic on megachilid coccons. They aappear to be increasing in numbers, clustering round the edges of the nest-holes. I have yet to see them actually enter the hole, but they are truly tiny (less than 3mm) and difficult to see, other than as a source of apparently continuous movement.

chalcid Pteromalus apum f

July 7th 2020. Another session at the flats brought an interesting digger wasp I had not seen for a few years. The spacing and clarity of the yellow bands on the abdomen, with a yellow scutellum, caught my eye immediately, such a splendid insect, searching the holes for a suitable site.

digger wasp Ectemnius cavifrons f

Another , but all black, digger was in and out of a few holes before vanishing for good down one of them, no doubt preparing the egg and its prey.

digger wasp Crocosserus megacephalus f

Nearby, a hoverfly framed a perfect portrait against an unusual view of a flower.

hoverfly Syritta pipiens m

Finally, I watched a male bumblebee taking in its rations of nectar, moving tirelessly from one flower to another.

bumblebee Bombus hortorum m

July 5th 2020. I spent a fascinating hour or so before lunch, watching the female leafcutter bees in action - not such a peaceful occupation as you might imagine. As far as I could see, they were all Megachile versicolor, one of the commoner species in our part of the world. The females are quite easy to identify once you get your eye in. The pollen brush, stretching along the length of the abdomen is pale yellow for all except the final section which is black, but beware that pollen swamping the colour of the hairs with its own dense colour. The bees have a number of actions, all of which were visible today. Clearly they spend time searching potential nest holes in the logs or bamboos, but that is a rapid process when they find the right-sized and empty hole. The next stage is construction of up to eight or so cells in the nest-hole. The bees fly in with roughly circular pieces of leaf cut from their favourite bush, varying by individual, carried tucked beneath the body in flight.

leafcutter bee Megachile versicolor f

These form the shape of the cell in which they then lay a single egg on a pile of pollen, after she brings this in beneath her abdomen.

leafcutter bee Megachile versicolor f

The last cell is closed off with considerable extra work, elaborate coatings of chewed up greenery cementing it all in place. The very last move is rather surprising - an untidy-looking leaf stuck on randomly, usually falling off after a few days. But the story does not end there. With help from a chemical process, the eggs hatch out in an orderlly stream, males first, then females, usually a week or so later; each individual letting the next one exit first, a highly organised, logical and automated process. But the really fascinating part of my visit was to watch a battle between two ladies for possession of a particular nest-hole. It was a study of titans at work. Who was right, and who was wrong, it was impossible to judge but clearly they were insensed with each other? I thought at first that the one was busy with final closure, but then a head appeared pushing back hard and so it went on. Eventually one appeared to give up, but then came back for another push and shove. It was still going on when I had to leave the scene. To the best of my observation both were M. versicolor but it is just possible the inner one was M. centuncularis and hence the fury.

leafcutter bee Megachile versicolor f

leafcutter bee Megachile versicolor f

 leafcutter bee Megachile versicolor f

leafcutter bee Megachile versicolor f

July 2nd 2020. I was only able to spend a little while in front of the logs today but spotted a couple of species I always enjoy seeing. This digger wasp is one of the many small, black, slender ones that can so easily defy identification. This one has a particular style which comes across as jaunty, smart, different, but with a head-shape that really is unique; broad in the front, narrower behind. The other feature is that it has a hairy fuzz around the head, where others do not.

digger wasp Pemphredon lugubris

The other picture, is of of a yellow-face bee, really tiny; the female is under 5mm long, the male slightly smaller and less bulky - if that is the right word for such a small creature? The first sign of them is of little black dots dancing round the logs, appearing and disappearing. When the pictures are examined on the computer, it is possible to see that they have yellowy-white markings on the face and yellow rings on the legs. The females lack pollen brushes, instead eating pollen and regurgitating it in its nest. So often, I look at them, photograph them, and only realise later what it is when I transfer the pictures to the computer. The moral is, always pay attention to the tiniest of insects.

yellow-face bee Hylaeus communis f

yellow-face bee Hylaeus communis f

The final picture is of a rather late Osmia caerulescens sitting on a stone which holds down some bmboo nest tubes. One characteristic is the shape of the while hair fringes on the abdomen, but is lacking another point; the insect does not show any metallic blue or green sheen. This feature appears to be variable, in spite of the name.

mason bee Osmia caerulescens f

 

 



Silver-washed fritillary Argynnis paphia

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