Hemerobius nitidulus

Scarce in Norfolk with just a handful of records in the Brecks, Kings Lynn/Dersingham area and this one below.

The presence of a recurrent humeral vein and 3-4 branches to the radial vein helps separate Hemerobius from Psectra and Micromus, and the position of veing RMCV (inside the fork of vein M) helps to rule out Wesmaelius. However, note that vein RMCV is often unpigmented in Hemerobius so you may need to look really carefully for this and it might not show up in photos.

This must be our least-marked Hemerobius with plain wings and no clouding around vein MCCV. Hemerobius nitidulus differs from micans in the length of the dark dashes along the forewing veins - on nitidulus they are no longer than the width of the vein.

Plant (1997) includes a note to say that if the specimen has an obvious orange-coloured pterostigma then it is more likely to be Hemerobius stigma, presumably indicating possible confusion between these two species. In the key, stigma is differentiated from nitidulus in having the membrane surrounding vein MCCV shaded darker than the rest of the wing membrane - presumably this can be subtle enough in stigma for it to be possible to go wrong and end up at nitidulus. Several images online purporting to be Hemerobius nitidulus show a slightly orange stigma, as does my specimen below - presumably therefore a slightly orange stigma is not a barrier to nitidulus, unless they are all misidentified. Certainly my one didn't have any hint of dark clouding around vein MCCV, so I presume the ID is correct. I will certainly be examining any future specimens very carefully indeed, especially if there is any hint of orange on the pterostigma.

Hemerobius nitidulus, North Elmham (Norfolk, UK), 2nd August 2018