Euura pedunculi - viminalis group (formerly Pontania pedunculi)
See Liston et al (2017) for determination of adults. The host plant is widespread. Within this group, males of Euura aquilonis, crassipes, collectanea, myrsiniticola, pedunculi, saliciscinereae, samolad, viminalis, herbaceae and arbusculae are inseparable.
Note that specimens determined as Euura brevicornis by Liston in 2012 have been re-identified as pedunculi and brevicornis is now removed from the British list.
Euura pedunculi larvae feed on Eared Willow, Goat Willow and its hybrid with Tea-leaved Willow. The final instar larva emerges from the gall to overwinter externally. The larva is uniformly brown and has minute pseudocerci on the supraanal plate so close together as to appear as one. The gall is usually in contact with the midrib, projecting only below the leaf-blade. The pea-shaped gall is variably hairy, often warty and green often flushed with red.
Size: Female: 2.5 - 4.3mm, male: 2.8 - 3.7mm
Distribution: England, Scotland, Ireland
Flight period: Univoltine, possibly bivoltine in Southern England
Plant associations: Salix aurita, Salix caprea and Salix caprea x phylicifolia (Eared Willow, Goat Willow and its hybrid with Tea-leaved Willow)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Liston, A.D., Heibo, E., Prous, M., Vårdal, H., Nyman, T. and Vikberg, V., 2017. North European gall-inducing Euura sawflies (Hymenoptera, Tenthredinidae, Nematinae). Zootaxa, 4302(1), pp.1-115.
Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168. https://doi.org/10.3897/BDJ.2.e1168
Vikberg, V. & Zinovjev, A. 2006: On the taxonomy and the host plants of North European species of Eupontania (Hymenoptera: Tenthredinidae: Nematinae). - Beiträge zur Entomologie, Keltern 56 (2): 239-268