Platycampus luridiventris - Flat Alder-cutter

North to Orkney, seemingly common and widespread (Musgrove, 2024).

Overall, a black insect with reddish-yellow legs which may be infuscated on the apices of the tibiae and tarsi. In the male, the tegulae, underside of the antennae and the hypopygium are brown. In the female, the edge of the pronotum and more or less the underside of the abdomen are brown. Sawsheath not projecting as far back as the long cerci.

Platycampus luridiventris larvae are unmistakable, being flattened against the leaf surface. They feed on alders and develop slowly, often to be found well into October. They make oval feeding holes in the leaf blade. In captivity, the final instar may cocoon in leaves or burrow into the substrate. The larva becomes an eonymph within the cocoon but prior to cocooning will empty its gut and holds its head in a more upright position.

Jump to information on the Platycampus genus

Size: 5 - 6mm

GB IUCN status: Least Concern
GB rarity status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: May to June

Plant associations: Alnus spp. (alders)

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 Natural England, unpublished