Monostegia abdominalis - Loosestrife Sawfly

Recorded widely in England and Wales north to Yorkshire, and more sparingly north to Ayrshire (Musgrove, 2023).

A frequent visitor to gardens with yellow loosestrife. The head and thorax are predominantly black but the clypeus, labrum, tegulae and edge of the pronotum are a drab orange. Mesopleura may also be tinged with orange. The legs are predominantly orange but bases of the coxae may be dark. Abdomen orange. Stigma and venation is dark except for the extreme base of wings. Previously thought to be parthenogenic in Britain, a single male was caught by Tony Irwin in Norfolk in 1982 and identified by Andy Musgrove in 2017.

Monostegia abdominalis larvae feed on yellow loosestrife, creeping jenny and scarlet pimpernel. The larvae coccoon in the ground. In summer generations, adults may emerge as quickly as two weeks after burying.

Jump to information on the genus Monostegia

Size: 6 - 8mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: Multivoltine, May to September

Plant associations: Lysimachia vulgaris, Lysimachia nummularia, Anagallis arvensis (yellow loosestrife, creeping jenny, scarlet pimpernel)


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.

Musgrove, A. 2019. A male specimen of the sawfly Monostegia abdominalis (F.) (Hymenoptera:Tenthredinidae) from Wheatfen, East Norfolk. British Journal of Entomology and Natural History, Vol. 32, BENHS, London.

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 Natural England, unpublished