Panorpa cognata

Very much the scarcest of the three species of scorpionfly in Norfolk. Brock has given this species the vernacular name Scarce Scorpionfly but this is not (yet) in widespread use.

Males are identified by the shape of the callipers on the top of their genital capsule. Actually, technically it's the bottom of the genital capsule, but since this is normally curved back over the rest of the abdomen so that it's upside-down, the callipers appear on top. These can be seen in a good quality sharp photo but be careful - it is easy to misinterpret this if the tips of the callipers aren't clearly visible in the photo and pin-sharp. Ideally retain the specimen until the identification is confirmed and verified. In both cognata and communis the callipers diverge (and to some extent they may in germanica too) but in communis (and germanica) they converge at their tips. The tips remain apart in cognata. The tips are fine in cognata, slightly less so in communis and broad in germanica.

Beware of photos where the tips of the callipers are not clear, either because of the angle (taken from slightly behind the insect) or because the photo is not sharp enough. Such photos can create the impression that the callipers diverge and do not come together again at the tips, leading to incorrect identification as cognata.

For females you must dissect the abdomen and examine the ovipositor. Note that differences in wing pattern have been described between the three species but the published differences (including the relatively recent one in Brock's Britain's Insects) are not sufficiently reliable to identify individuals on these characters alone.

After examining 70 Panorpa germanica and 36 Panorpa communis I finally came across my first Panorpa cognata. Its identification was suspected in the field based on the wing pattern (the solid bar crossing the wings is thick in the outer half and much reduced on the inner half, plus there is a narrow pale band between the dark apical patch and the wing margin) and the brown-centred thorax (typically yellow-centred on the other species but not always). Fortunately I managed to get this one in a pot so I was able to examine its callipers to confirm the identification.

male Panorpa cognata showing callipers in genital capsule, Wendling Beck Environment Project (Norfolk, UK), 31st July 2024