Cladius (Trichiocampus) ulmi (Linnaeus, 1758)

Cladius ulmi - Elm Knucklehorn

Cladius (Priophorus) ulmi (Linnaeus, 1758)
Cladius (Trichiocampus) ulmi (Linnaeus, 1758)
Cladius eradiatus Hartig, 1837
Priophorus laevifrons Benson, 1936
Priophorus ulmi (Linnaeus)
Tenthredo ulmi Linnaeus, 1758

North to southern Scotland. Apparently the more common of the two elm-feeding Cladius species, the assessment of which is clouded by unhelpful nomenclatural issues. Records assigned to 'ulmi' may have been subject to confusion, as Benson's Priophorus ulmi is not the same taxon as the currently recognised Cladius ulmi. Likely to have been affected by Dutch Elm Disease, but clearly able to persist on smaller hedgerow plants in the absence of larger trees (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 (Priophorus laevifrons).

The head on the frons and temples above smooth and shining without sculpture or hair-warts. Cladius ulmi is a black sawfly with pale tibiae and tarsi on all legs. The wings are subhyaline. The abdomen without any brown spot in the middle of the first tergite.

Larvae feed on elm creating holes in the leaf surface between the veins. They can be distinguished from the other elm feeding species, Cladius rufipes, by the presence of a black spot on the front of the face which is absent in rufipes.

Jump to other Cladius species

Size: 5 - 6.5mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: Bivoltine, May to August

Plant associations: Ulmus spp. (elms)

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

: Cladius ulmi female ex larva on elm Credit Mark Boddington

: Cladius ulmi female ex larva on elm Credit Mark Boddington

: Cladius ulmi larva Credit John Grearson

: Cladius ulmi larva Credit Mark Boddington

: Cladius ulmi on elm middle instar Credit Andrew Green

: Cladius ulmi on elm middle instar Credit Andrew Green

: Cladius ulmi on elm middle instar Credit Andrew Green

: Cladius ulmi on elm middle instar Credit Andrew Green

: Cladius ulmi leaf damage Credit Andrew Green

References:

Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London

Chevin, H. 2003: Biologie et description de la larve de Priophorus ulmi (Linné, 1758) (Hymenoptera, Tenthredinidae, Cladiinae). - Bulletin des Naturalistes des Yvelines, Versailles 30: 61-64.

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.