Trioza urticae

Length 3 to 3.5 mm. This psyllid bug or jumping plant louse is a reasonably distinctive species in a large and difficult genus. Distinguishing features include the relatively rounded (for Trioza) forewings with long outer vein, which together with its occurrence on nettles, make it reasonably easy to identify, although colouration is quite variable. The three main veins arise from a single point, which is the thing that distinguishes Triozidae. Early instar nymphs are pale, but the later stages have a distinctive black patterning. 

It causes galls on nettle; the young leaves are curled up and darker green, with the flat psyllids in a small depression beneath.

Anywhere that nettles are present. This is the only UK nettle-feeding psyllid.

All year round. 

Nymphs cause galls on nettle leaves. The adults overwinter, and there can be as many as four generations in the UK per year.

Widespread and common in Britain.

Common in Leicestershire and Rutland.

British Bugs: https://www.britishbugs.org.uk/homoptera/Psylloidea/Trioza_urticae.html