The aphids have already been busy forming galls on the Lombardy Poplars Populus nigra var. italica down Oasis Way in Hunstanton. The spiral galls on the petioles are caused by the aphid Pemphigus spirothecae. Some of the leaves have a swollen midrib on the upper surface with a slit opening on the lower surface. This can be caused by three aphids: Pemphigus filaginis, P. gairi and P. phenax. The latter two have yellow green nymphs whereas those of P. filaginis are slate grey.
Swollen midrib gall and spiral gall on Lombardy Poplar leaf
Underside of leaf with slit opened up to show aphid nymph
Nymph of Pemphigus filaginis