Fenusa ulmi - Elm Mining Sawfly
= Kaliofenusa pusilla (Audinet-Serville, 1823)
= Fenusa (Kaliofenusa) altenhoferi Liston, 1993

Historically the two Kaliofenusa species were only separated in Britain in 1994. There appears to be little morphological or genetic difference between the species of Kaliofenusa and some authors now consider Kaliofenusa species as a single species under the name Kaliofenusa pusilla. In the 2023 status review, the two species were treated as one under the name ulmi. 

Widely recorded throughout all of mainland Britain, as well as on Skye (Musgrove, 2023).

Fenusa ulmi is an almost entirely black species with only the legs sometimes brown. In the female, the sawsheath appears to be unreliable for identification. In this species the frons has lateral walls that are almost straight-sided and lateral foveae are contained within elongated, narrow furrows that extend above the frontal furrow.

Eggs are deposited in the mid-veins of wych elm from where the larva forms a blister mine that often does not reach the leaf margin. The Kaliofenusa species appear to prefer suckers and regrowth.

Jump to other species of Fenusa

Size: 3 - 4mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: Bivoltine? April to June and August.

Plant associations: Ulmus glabra (wych elm)

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. D. 1994. Kaliofenusa carpinifoliae LIston (Hymenoptera: Tenthredinidae), a newly recognised leafminer on field elms in Britain. British Journal of Entomology and Natural History, vol.7 (1), pp15-18.

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 Natural England, unpublished