This is the Hoplocampa associated with apple species. Predominantly black bodied above and orange below. The head is orange with a central black patch. The stigma and wing venation are brown or dark. The stigma is clearly darker at the base than the apex.
Hoplocampa testudinea females cut and lay eggs into the ovary behind apple blossom. The larva feeds inside the developing fruit. The damaged fruit will drop before maturing, at which point the larva leaves the fruit and pupates underground. Larvae may migrate to a second fruit. If the larva dies but the fruit matures, a large circular scar on the surface of the apple is diagnostic.
Status: Locally common
Distribution: England, Scotland, Wales
Flight period: April to May
Plant associations: Malus pumila (apple)
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, 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
Liston, A., Prous, M. and Vårdal, H., 2019. A review of west palaearctic Hoplocampa species, focussing on Sweden (Hymenoptera, Tenthredinidae). Zootaxa, 4615(1), pp.1-45.