Bourneside Meadow

The butterflies were superb at Bourneside Meadow today. It was particularly nice to see the Small Copper, Lycaena phlaeas, although Warren also saw it today at Pittswood and at the Nursery of Ashes Lane, so I suspect it may be more widespread across the parish than I had realised.

I saw several male Common Blue, Polyommatus icarus, males but they were moving too quickly to be photographed. These must be early representatives of the second generation of this summer, which has started just this last week, after a break of about a fortnight from the first generation. Singles or pairs are regularly seen by Warren every summer, so this suggests adults of this species should also be fairly well spread across the parish. This butterfly forms reasonably discrete colonies measured in tens or hundreds, with individuals occasionally wandering some distance.

This species is most active in sunshine and is a frequent visitor to flowers. Males are the more active of the two sexes and set up territories which they patrol in search of females. The female is less conspicuous, spending most of her time nectaring, resting and egg-laying. When egg-laying, the female makes slow flights, low over the ground, searching out suitable foodplants on which to lay. When a suitable plant is located, a single egg is laid on the upperside of a young leaf (UK butterflies), which should be fairly clearly visible.

In dull weather this species roosts head down on a grass stem. As for similar species, such as the Brown Argus, this species roosts communally at night, with several individuals occasionally found roosting on the same grass stem.

The chrysalis is attended by ants, which may take it into their nests, feeding off the honeydew it may excrete.

One of the clues as where the Common Blue breed is going to be the location of the larval food plants. I checked some of the Birds-Foot Trefoil plants in the meadow and I thought most of them were Greater Birds-Foot Trefoil, Lotus pedunculatus, but at least some definitely looked like Common Birds-Foot Trefoil, Lotus corniculatus, as in the relatively hairless plant with (only 3) orange flowers below. Both are included in the fairly wide ranging list of trefoils and medicks that are used as larval foodplants, so this species of butterfly should do well on this particularly rich patch of wild flowers.

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I also spotted (I think) a Brown Argus, Aricia agestis, picking it out from the Small/Essex Skippers as it fluttered past me, found where it had settled, and grabbed a very poor photo just to confirm the record of the colony. The wings are a good chocolate colour and there are good orange spots around the edge, with no blue dusting towards the body, so I do not think it is a Common Blue female. From the rather rounded wings and the full extent of the orange spots it is possibly a female rather than a male Brown Argus. As it seems quite fresh this might be one of the first of the second generation this year.



On one of the Hogweed heads there was a Crabronid wasp, Crabroninae. The wings lie flat across the abdomen. It is very likely to be an Ectemnius species. Sometimes you find Cerceris species in Philanthinae but these are quite easily distinguishable, by the unevenly ridged segments of the abdomen, the head shape, the yellow face and the overall jizz,  http://www.ispotnature.org/node/281557  and http://www.ispotnature.org/node/280405. The yellow proximal sections of the antennae suggest Ectemnius rather than the otherwise very similar Crabro, where the antennae are black overall.

Another confusion possibility is Mellinus arvensis, generally late in the season, and without the yellow on the bottom of the antennae, or the silver or gold hairs on the clypeus, and with more orange rather than yellow legs.

As to getting down to species, this is very difficult - useful notes from Ardea:

"For female ID you need to get a clear view of the shape of the clypeus (basically upper lip) which you can only see well from the underside of the head, against the light. The clypeal hairs obscure the shape from the front. WIth your photos, long Mesonotal hairs, golden clypeal hairs = either lapidaries, ruficornis (scarce), cavifrons and sexcinctus."