Cacopsylla ambigua

Previously known as Psylla ambigua but now placed in the genus Cacopsylla.

This was taken on hazel, whereas ambigua is supposed to be on willow. I don't think that's too big a problem - they have wings and there was lots of willow in the immediate vicinity, and in any case as far as I can tell none of the British species are supposed to be on hazel. It keyed directly to ambigua with no significant issues. The shape of the tip of the abdomen seems right, although the overall length of the proctiger seems a little long. The genal cones shape doesn't seem a perfect match for the figure for ambigua in the key - it looks more like melanoneura in this respect but I'm pretty certain it isn't that. On balance ambigua seems to be the best fit, so this is what I am tentatively calling it - but as always I welcome correction (or confirmation) from anyone with more experience of psyllid identification.

female Cacopsylla ambigua showing wings (with close-up of end of forewing), genal cones (pre- and post-clearing) and abdomen tip (pre- and post-clearing), Wendling Beck Project (Norfolk, UK), 14th May 2022

Finding and identifying this highlighted to me that an insect I had previously identified as Cacopsylla ambigua was incorrectly identified. I have now reviewed that and believe it to be a (teneral?) Cacopsylla melanoneura - so have moved the images and account to that page.

This one was swept from willow. It keyed straightforwardly to ambigua, was on the correct foodplant and the genal cones and terminalia compared well with the diagrams in the RES key. The wing spiculation is so faint and dense that I could only just see it under the dissecting microscope - the compound microscope providing a better view. In this respect it was exactly like the one above, and at first that helped me feel more confident that I had identified that one correctly - but then I noticed that the terminalia of the last one look distinctly longer than they do on this one... The forewings of this one were 2.8mm long.

female Cacopsylla ambigua showing forewing (with close-ups under both microscopes), genal cones and terminalia, North Elmham railway (Norfolk, UK), 2nd May 2026