Cacopsylla cf. affinis

Cacospylla affinis was previously known as Psylla subferrugineus, the name used in the RES key.

This came to light in my garden. It struck me as being quite different to the numerous Cacopsylla melanoneura which I have caught here previously, most obviously due to the very strong yellow suffusion on its forewings. I have observed some variation in the degree of suffusion (or lack thereof) on melanoneura but I have never caught one approaching this before. The entire insect seemed brighter and cleaner than is usual on melanoneura too, although there is much variation in melanoneura body colour and some certainly approach this (and nothing I've read suggests that colouration is helpful for separating these two species). Using the RES key, this keys straightforwardly and clearly to Cacopsylla affinis (or rather Psylla subferrugineus, the name that key uses for this species), and I suspect that this may well be the correct identification. However, other sources (including the British Bugs websitse and James Emerson's excellent NNNS guide to the Psyllids of Norfolk) state that melanoneura and affinis can only be reliably separated by male genitalia. Sadly this one was a female, so I guess that means that I cannot exclude the possibilty that it was an extreme melanoneura and therefore cannot record it as a certain affinis.

There was a large Birch tree (birch is the foodplant for affinis) in the garden behind mine, and I also have a mature Birch tree in my front garden. Hopefully I will catch a male in due course so that I can confirm the species' presence here - although sadly the neighbour's birch tree was cut down due to disease in the autumn after I caught this, so that might reduce my chances.

possible female Cacopsylla affins showing front of head including genal cones, wings (with close-up of part of forewing) and terminalia, North Elmham (Norfolk, UK), 27th July 2025