Mealy Plum Aphid Hyalopterus pruni

Also known as Reed Aphid, this species host alternates between Plum (or sometimes other Prunus species) and Reed.

According to the Influential Points website winged alatae start to develop on the primary host, Plum, in early June with the peak migration of alatae to the secondary host, Reed, taking place between early July and early August. I don't know how long it is then before nymphs appear, but given the number and range in size of nymphs on this Reed leaf, and the date in early June, it seems to me that the alatae must have developed and migrated quite early.

Mealy Plum Aphids Hyalopterus pruni, Wendling Beck Environment Project (Norfolk, UK), 4th June 2025