The Apterae of Macrosiphoniella millefolii are of moderate size, green and wax powdered except for a spinal stripe on the abdomen and presiphuncular spots 

Gall Adult

Good photographs required, please state the host species when submitting records.

Macrosiphoniella millefolii mainly feeds on Yarrow (Achillea millefolium), but it has been found on many other Achillea species, as well as on daisies (Leucanthemum), tansies (Tanacetum) and mayweeds (Tripleurospermum spp.) it is usually found in areas where these host plants are present.

It causes galls in flower heads; the head becomes rounded or compressed, with thickened petioles

Overwintering eggs, laid on the stems of yarrow (Achillea millefolium) the previous autumn, hatch in spring to give fundatrices. These reproduce parthenogenetically giving birth to live young which mature and reproduce in turn. By mid-June there can be dense colonies of Macrosiphoniella millefolii living on the flower stems of their host plant.

It does not host alternate, but does have a sexual stage in its life cycle.

Not regularly recorded in Britain which makes status difficult to determine.

Infrequently recorded in Leicestershire and Rutland.

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