Poplar Spiral Gall Aphid Pemphigus spyrothecae

Family Aphididae (Aphids) » Pemphigus (Pemphigus) spyrothecae Passerini, 1860
Gall length up to 12 mm. Pemphigus spyrothecae is an aphid that causes spiral galls to form in the leaf petioles of poplar trees, especially Black Poplar (Populus nigra) and the hybrid Lombardy Poplar (Populus nigra ‘Italica’). Interestingly there are at least two castes: one simply feeding and reproducing, the other which are soldiers which tend to line up along the dividing ridges. The soldiers are morphologically distinguishable and, in defending the colony, are often themselves killed. Altruism is rare amongst aphids. The production of specialist castes( specialists that fulfill particular functions like division of labour) is a feature of organisms that live in colonies, like ants and bees. The galls are seen from June to late autumn wherever the host plant grows. Widespread and thought to be fairly frequent in England.

Discovered on poplar, local park, South Staffordshire. 1st October 2021. Photos © Peter Hillman.