Dolerus aericeps - Red-backed Weeper

Often appearing later in the year than other adult Dolerus species. Recorded widely across all of mainland Britain, as well as the Hebrides (Musgrove, 2023).

In the female the mesonotum is red at least on the side lobes and with a black scutellum. Usually the front lobe is red but black is not uncommon. The mesopleurae are heavily cratered in the middle. The abdomen is orange with a black base to the sawsheath. The female is similar to Dolerus madidus and Dolerus triplicatus. In madidus and triplicatus the legs are entirely black, whereas aericeps has red about the knees.

In the male the thorax is entirely black. The knees and most of the length of the tibiae are red. The head is bronzey. Dolerus aericeps is one of only two Dolerus species found on the wing in mid to late summer. This species is best identified by the genitalia.

 Larvae feed on horsetails in wet areas.

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GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: May to September

Plant associations: Equisitum sp. (horsetails - wet habitat species)

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, 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

Musgrove, A.J. 2023. A review of the status of sawflies of Great Britain - Phase 2: The Athaliidae and the Tenthredinidae (excluding Nematinae). Natural England, unpublished