Alebra albostriella

3.2mm - 4.5mm (females are larger than males); associated with English oak Quercus robur.  The Alebra genus is distinguished from all other Typholocybinae by the forewing appendix - a narrow zone at the forewing apex which is not crossed by any veins.  Individuals vary in colour and intensity of markings, and males and females differ.   The hind tibia have dark spots and the ventral side of the abdomen is partially dark, with a lighter apex. 

Some females have longitudinal yellow, orange or red stripes down pronotum and forewings, with yellowish head and vertex. Another female form has a dark blotch on vertex and pronotum and a darker median band across forewings. Males are often less well-marked and greenish-orange.

There are several similar Alebra, and identification is difficult. If in doubt, the male sternal apodemes should be examined - these are internal abdominal structures assocated wth the song apparatus.  

other Alebra - A viridis is v. similar but on Sessile Oak, Quercus petraea.   Alebra coryli on Hazel is also striped yellow/orange and white, but has light ventral abdomen and no dark spots on tibia.

Detailed examination of the specimen is needed to identify this species.  Photograph underside as well as dorsal side, and ensure hind tibia are clearly shown.  You must identify the host plant - including which species of oak.  It is helpful to confirm whether male or female. See Biedermann & Niedringhaus for illustrations of sternal apodemes, and Le Quesne for guidance on how to examine them.

Usually Pedunculate Oak (Quercus robur).

Adult: June to October

Common (ref: UK Auchenorrhyncha checklist 2021)

Probably common, but status obscured by ID difficulties.

https://www.britishbugs.org.uk/homoptera/Cicadellidae/Alebra_albostriella.html