Friday 28 September 2012

Reservoir path at Tudeley

Its very late in the year now, and hoverflies seem few and far between. The weather was poor, with a cool breeze blowing clouds across the sky intermittently threatening rain. However I wanted to try an area that had water near by, with a chance of a few remaining flowers, as dry flowerless areas seem to make very poor hunting grounds. The reservoir path at Tudeley looked good, although ideally I would be out reasonably early in the morning, not towards the end of the afternoon.

I was looking for anything and everything: spiders, bugs, leaf-miners and fungi. I moved slowly, hoping that shyer stuff would show itself. Suddenly I saw a small hoverfly moving slowly low down in the foliage by the side of the path, and on first sight it looked as though it had a waisted abdomen, and I thought could this be my first Baccha elongata, long overdue for such a common species. So it turned out, although the photos were tricky, and it could be argued that I should stick to Baccha sp. as an ID, allowing for a split to be re-established between the two original species suspected to exist in the UK, Baccha elongata and Baccha obscuripennis. This is a female, the males may be even  more elongate!

The eyes on this fly look almost absurdly large and wide on the head, especially in comparison to the very narrow abdominal segment 2! I am so glad to see this species at last, this individual presumably being part of the known second peak in the year, which is said to be in September by S & F.


The yellow banding on the rear edges of tergites 2 and 3 are more visible in this blurry photo of the insect in flight:


The abdomen didn't seem swollen with eggs in the next photo, and I couldn't see any of the reddening of the female abdomen that often seems to be associated with such swelling.


In some of the photos on the web (although I don't get much of this from my photos except maybe this last one) it looks as though the wings are slightly spotted, with the stigma and a couple of slightly discoloured cross veins all about half way along the wings, and maybe at the tip. On the website "LifeDesks Flower Flies Syrphidae (entry by Ximo Mengual)" it quotes the following "cross-veins and extreme apex of the wing faintly clouded in some specimens", so that seems to fit.

The yellow rear edges in this photo look a bit more like spots than bands here, although this isn't supported by the photo of the fly in flight - again however there is some support from this on the LifeDesks website entry. Tergite 4 looks to have the start of some yellow at the rear of the tergite, small hints of triangles on  the lower sides. I also think I believe some yellow dusting (pruinose?) on the lower thoracic pleura.


This fly is said to be rather a shade-lover, and rather more difficult to spot than some! Having seen one I'll have to keep my eye out for some more! The habitat here certainly fitted part of the S & F habitat profile, a shady woodland ride, quite humid with nettle beds close to hand.