Sterictiphora geminata - Dark Twinhorn
One of two species in this genus widely distributed north to Sutherland (Musgrove, 2022). The abdomen is mostly black with a bronze sheen (in S. angelicae only the first two tergites are black) and thorax surface is dulled by microsculpture and puncturation.
Sterictiphora geminata larvae feed on roses and occasionally Mountain Ash. Other larvae of this genus feed from the edge of the leaf working inwards in a meandering zig-zag pattern similar to the Elm Zig-zag sawfly.
Size: 5 - 7mm.
IUCN Status: Least Concern
GB Rarity Status: None
Distribution: England, Scotland, Wales, Ireland
Flight period: April to June
Plant associations: Rosa spp., roses (Benson, 1952) and Mountain Ash, Sorbus aucuparia (Liston, 1995).
The National Biodiversity Network records are shown on the map below. (See terms and conditions)
- Sterictiphora geminata female Credit Martin Elkins
- Sterictiphora geminata female Credit Martin Elkins
- Sterictiphora geminata female Credit Martin Elkins
- Sterictiphora geminata male Credit Ian Andrews
- Sterictiphora geminata Credit Ian Andrews
- Sterictiphora geminata Credit Ian Andrews
- Sterictiphora geminata Credit Jane Hewitt
- Sterictiphora geminata middle instar larva on wild rose Credit Andrew Green
- Sterictiphora geminata middle instar larva on wild rose Credit Andrew Green
- Sterictiphora geminata middle instar larva anal segment Credit Andrew Green
- Sterictiphora geminata middle instar larva lateral glands Credit Andrew Green
- Sterictiphora geminata early instar larva on wild rose Credit Andrew Green
- Sterictiphora geminata early instar larva on wild rose Credit Andrew Green
References:
Benes, K. 1968: Description of the Larvae of Sterictiphora geminata and Cladardis elongatula (Hymenoptera, Symphyta). - Acta entomologica bohemoslovaca, Praha 65(3): 222-225
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., 1995. Compendium of European Sawflies, Chalastos Forestry, Daibersdorf
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
Lorenz, H. and Kraus M., 1957. Die Larvalsystematik der Blattwespen (Tenthredinoidea und Megalodontoidea). - Abhandlungen zur Larvalsystematik der Insekten No. 1. Berlin: Akadamie - Verlag
Musgrove, A.J. 2022. A review of the status of sawflies of Great Britain - Phase 1: families other than Tenthredinidae. Natural England, unpublished