Family Tenthredinidae (Common sawflies) » Euura pedunculi (Hartig, 1837)
Gall width 5 mm. The sawfly Euura pedunculi causes pea-shaped galls to form on the underside of sallow (salix) leaves. It is pale green in colour and sometimes tinged red. The surface may be hairy , especially on Goat Willow (Salix capraea). The gall’s position is marked on the upper surface by a yellowish scar, either flush with the surface or very slightly raised. Galls on Salix caprea are usually near the tip of the leaf. There are two generations per year. The adults are rarely seen, but the galls are common in England wherever the host plant grows.
Discovered on Goat Willow (Salix capraea), alongside canal towpath, South Staffordshire. 1st October 2021. Photos © Peter Hillman.