The aphid Cryptosiphum artemisiae forms, and lives within, red globular leaf galls on Mugwort (Artemisia vulgaris).

The apterae are of moderate size, greyish-green and wax powdered. The antennae and legs are mostly black, except for the base of antennal segment 3 and the basal part of the front femur which are brown. The siphunculi and cauda are entirely black.

Gall Adult

Adult: Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Wherever Mugwort is present.

Galls may be encountered when Mugwort is in leaf.

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

Status in Leicestershire and Rutland not known.

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