Cladius pectinicornis - Stag Knucklehorn

Cladius (Cladius) pectinicornis (Geoffroy, 1785)
Cladius difformis (Panzer, 1799)
Nematus crassicornis Stephens, 1835
Tenthredo difformis Panzer, 1799
Tenthredo pectinicornis Geoffroy, 1785

North to Orkney, seemingly common and widespread. Benson (1958) described this as 'one of the commonest of sawflies' and, with the exception of three gall-making species, this remains the most frequently recorded member of the Nematinae. Note that Cladius difformis, as recognised by Benson, is lumped within C. pectinicornis. (Musgrove, 2024). According to Prous et al, 2019, there is currently no reliable key or species treatment available for this genus. The description follows Benson.

The head is shiny above without sculpture or hair-warts. A black sawfly with pale tibiae and basal tarsi on all legs. Females of Cladius pectinicornis are difficult to identify. The male antennae have almost equally long projections to the three basal flagella a shorter projection on the fourth and a minute projection on the fifth. The projection on the first flagella is about as long as the length of the following segment.

Larvae feed gregariously on roses, strawberry and greater burnet.

Jump to other Cladius species

Size: 5 - 7mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: Bivoltine, May to September

Plant associations: Rosa spp., Fragaria spp. and Sanguisorba officinalis (roses, strawberries and greater burnet)

The National Biodiversity Network records are shown on the map below. (See terms and conditions)

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. 2024. A review of the status of sawflies of Great Britain - Phase 3: The Tenthredinidae (subfamily Nematinae). Natural England, unpublished

Prous, M., Liston, A., Kramp, K., Savina, H., Vårdal, H. and Taeger, A., 2019. The West Palaearctic genera of Nematinae (Hymenoptera, Tenthredinidae). ZooKeys, 875, p.63.