Euura triandrae (Benson, 1941)

Euura triandrae - proxima group (formerly Pontania triandrae )

See Liston et al (2017) for determination of adults. Males are rare. There is some doubt as to whether this is in fact a species separate to Euura proxima.

Larvae feed on almond willow causing coffee bean shaped galls that transect the leaf blade but grow more on the upper surface . Single, or very few galls per leaf. The galls are green becoming dark red or brownish above, yellow-green below, and with a smooth surface. There is some doubt as to whether the gall characteristics are useful as an indicator of the species or whether they are caused by the host plant.

 

Size: Female: 2.9 - 4.5mm, male: not assessed

Status: Local

Distribution: England, Scotland, Ireland

Flight period: Bi- or multivoltine

Plant associations: Salix triandra (almond willow)

References:

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