The body length of the Aphis newtoni aptera is around 2 mm and they vary from reddish brown to almost black.

Please supply images to support your record and, where possible, gain expert confirmation of species identification before submitting the record. Please state the host plant on which the aphids were found.

The Iris aphid feeds in large ant-attended colonies on Iris, often the Yellow Iris (Iris pseudacorus). 

Oviparae and apterous males are produced in autumn.

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

Status in Leicestershire and Rutland not known.

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