Chrysopa dorsalis

Although there's a 1960s record from Holkham, the only recent records of this species in Norfolk have been from Dersingham (2018) and Holme (several records). Recent records have all been in July and August.

The extensive dark markings on this species make it quite distinctive, though it needs to be separated with care from the much commoner and widespread Chrysopa perla. It shares the bluey tinge to the green of that species though on the specimen I've seen this was only really apparent on the thorax and even there not particularly obvious from above. The main differences from Chrysopa perla are the black subcostal vein (one of the pair of long veins running almost the full length of the wing) - green on Chrysopa perla. The shape of the pale spot at the middle of the back of the head is also different - more circular in perla and more oval or rectangular on dorsalis (although on the specimen I've seen, shown here, it was more triangular). The tarsal claw is also not toothed at the base, but it is expanded at the base so the difference is not easy to see.

I'm grateful to Dave Norgate for looking out for, finding and bringing me this specimen which came to light at Holme. It was more distinctive than I expected. The thick black lateral stripe through the thorax is much stronger, thicker and more solid than I've ever seen on Chrysopa perla, and this is matched by other photos of Chrysopa dorsalis online, or nearly so. On all the Chrysopa perla I've seen this is broken into two or three spots, albeit to some extent these may be joined. The black down the dorsum of the abdomen was also more solid and continuous than I've seen it on Chrysopa perla, and again, photos online suggest this is normal - although not necessarily to the same extent as on this one. Some photos of Chrysopa dorsalis online show the dorsal stripe to be narrowly broken in places but on Chrysopa perla it is normally more clearly broken at the join of each segment. Finally the head on this specimen was much more extensively black than I expected, however this does not seem to be normal for dorsalis. On most photos online the front of the head is extensively green (almost entirely black on this specimen) and usually the green spots at the sides of the back of the head are more obvious (tiny and indistinct on this specimen).

Chrysopa dorsalis showing (from sixth photo onwards) close-up of head from above, forewing, tarsal claw, abdomen tip from side and underside, Holme NOA (Norfolk, UK), 2nd July 2024