Length 4.5 - 5.5; females larger than males.  Sexually dimorphic and variable in colouration and intensity of markings.  Nymphs cannot be verified.

Males have dark scutellum with yellow spots towards apex and dark veins on forewings, with hyaline cells often with smoky suffusion at the apex.  Males usually have weak dark markings on the face and lack the prominent discoidal spots of O flavicollis, but this is variable.  Examination of male genitalia (pygofer appendages) will separate from O flavicollis.  Females have a heart-shaped rusty-brown area on the face, with a darker border.   The shape of the ovipositor is longer and straighter than O flavicollis.

Other Oncopsis, especially Oncopsis flavicollis.  Both species are associated with birch and are often found together

Detailed examination of the specimen is needed to identify this species. Clear photographs of the face should be provided.  Provide measurement and whether male or female.  You must note the host plant.

Birch.

Adult: May to September.

Local. (ref.: UK Auchenorrhyncha checklist 2021, on British Bugs website)

Rarely recorded

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