Strongylogaster multifasciata - Striped Fern-sawfly

Recorded commonly and widely across all of mainland Britain, as well as from the Hebrides, Scilly and Lundy (Musgrove, 2023).

A black and tan species and the commonest in this genus. This species is very similar to the rarer Strongylogaster xanthocera.

In some localities males of multifasciata appear to be rare, whereas S. xanthocera males are more frequent than xanthocera females. Males of multifasciata have the first tergite marked with yellow on the lateral faces and the yellowing is greater on tergite 2. In the male of xanthocera the abdomen has the first tergite black right to the lateral margins and usually with at least the second tergite black also.

In Strongylogaster multifasciata females, the third antennal segment is only partially yellow, the epipygium is usually brown and the hind femur is usually only black basally. Females of xanthocera have at least the first three antennal segments yellow, the epipygium is usually black and the hind femur is usually black almost to the apex. The anal cells of the fore wing lack a cross-vein. The labrum is black. The sawsheath of the female is divergent at the apex.

The green larvae feed on ferns. The head is marked with black on each temple and there is no black mark on the anal segment.

Jump to other Strongylogaster species

Size: Approx. 9 - 11mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: May to September

Plant associations: Pteridium aquilinum (bracken) and Dryopteris filix-mas (male fern)

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. 2023. A review of the status of sawflies of Great Britain - Phase 2: The Athaliidae and the Tenthredinidae (excluding Nematinae). Natural England, unpublished

Macek, J., 2010. Taxonomy, distribution and biology of selected European Dinax, Strongylogaster and Taxonus species (Hymenoptera: Symphyta). Acta Entomologica Musei Natioalis Pragae, 50(1).