Immature Tuberculatus annulatus are yellowish or green with pale antennae apart from black bands at the tips of the segments. The adult winged viviparae are very variable in colour, ranging from yellowish, greyish-green or pink to purple in summer. For more information see the ‘Further info:’ link below.

Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features, then in the comments box describe the size and identifying characters you have observed.

On Oak, especially English (Pedunculate) Oak.

When English Oak is in leaf.

True status in Britain is difficult to determine due to lack of records.

Rarely recorded in Leicestershire and Rutland.

https://influentialpoints.com/Gallery/Tuberculatus_annulatus_Common_oak_aphid.htm