The alates (winged adults) have widely separated broad black bands on the abdomen which helps with identification. The alate body length is  3.2 to 4.5 mm.

The apterae (wingless forms) are yellow-green and can be much more difficult to identify to species.

Alates may be identifiable from good images, It may not be possible to verify the yellow-green apterae from photographs.

This species lives on the underside of Acer species, especially Norway Maple, but also on Field Maple.

Most likely to be encountered in late spring and summer.

Not usually ant attended.

There are only a few scattered records of Periphyllus aceris in Britain, possibly due to lack of recording effort rather than scarcity of the species.

Rarely recorded in Leicestershire and Rutland.

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