Nematus brischkei (formerly Craesus brischkei) - Brischk's Regal-sawfly

One of four Nematus species in Britain and Ireland characterised by the enlarged basitarsal segment. Rare and/or unobtrusive, recorded from Hornbeam in Bedfordshire in 1948 and 1949 (Chambers 1950), and from Hazel in Warwickshire in 2023 (Musgrove, 2024). More recently reported from Hertfordshire in 2024. This species is shining in the centre of the upper part of the mesopleura with the punctures clearly discernible amongst very fine microsculpture (Nematus alniasti lacks microsculpture here). The femora are mainly black. Males are unknown.

Nematus brischkei larvae are solitary feeders (at least in late instars) on hornbeam and hazel. The larvae have yellowish prolegs and are less marked than alniastri.

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Size: 7 to 8mm

GB IUCN Status: Vulnerable
GB Rarity Status: Nationally Rare

Distribution: England

Flight period: May to June

Plant associations: Carpinus spp. and Corylus spp. (hornbeams and hazels)

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

Chambers, V. H. 1950: Croesus brischkei Zaddach, a sawfly (Hym., Tenthredinidae) new to Great Britain. - The Entomologist's Monthly Magazine, Fourth Series, London 86(11): 85-86

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 Natural England, unpublished