Recorded widely across much of Britain, including Orkney. Benson (1952) described the range as extending 'north to Dumfries, sparingly', and hence a range expansion northwards would seem to have occurred. It is noted that an unknown but probably small proportion of records may have actually referred to the similar Tenthredo semicolon (Musgrove, 2023).
One of five Tenthredo species with a band of white antennal segments: colon, fagi, ferruginea, livida, semicolon. In colon and semicolon the white is confined to at most segments six to eight. The stigma of the forewing is unicolorous brown and the costa yellowish-brown. The scutellum is black and never white marked. The metapleuron and lateral face of the first tergite are each white-marked. The head above is mostly impunctate and shining black.
Tenthredo semicolon has previously been confused with colon. Tenthredo colon has more microsculpture on the mesopleura and mesosternum giving it a duller appearance. The hind femur has at least the apical third black, whereas in semicolon it is only black at the extreme apex. The most reliable characteristic is the lancet where the more basal teeth in colon are relatively flat. In semicolon, they are subtriangular and strongly produced.
Tenthredo colon larvae feed on a broad range of plants.
Size: 10 - 12mm
GB IUCN Status: Least Concern
GB Rarity Status: None
Distribution: England, Scotland, Wales, Ireland
Flight period: May to August
Plant associations: Circaea lutetiana (Enchanter's Nightshade), Epilobium hirsutum (Great Willowherb), Pteridium aquilinum (Bracken), Fuchsia spp. (Fuschias) and Salix spp. (Sallows, Willows)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Fekete, K. (2018) Beginner’s guide to identifying British Tenthredo, Natural History Museum, London. http://www.nhm.ac.uk/content/dam/nhmwww/take-part/identification-trainers/sawflies-guide-id-trainees.pdf [Accessed 26Apr2019]
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 Natural England, unpublished