Eutomostethus luteiventris

Distinguished from similar sawflies by the combination of black head and thorax with orange-yellow abdomen bearing black dorsal markings. The small size (5–7 mm) and association with rushes (Juncus) in damp habitats provide additional diagnostic context. In Britain and Ireland, the absence of males may aid identification, though this trait is not externally visible.

Damp places, typically associated with stands of rushes (Juncus spp.).

Common throughout Britain and most of Europe; introduced in North America. Recorded in Belgium (Flemish and Walloon regions), Canada (Alberta), and the UK (specimen from Thompson Common, Norfolk).

Single generation per year in the UK. Adults occur from late April to June.

Larvae feed on rushes (Juncus spp.). Early instars feed inside foliage; final instar feeds externally.

• Juncus spp. - larval host plantLarvae feed inside foliage initially, then externally in final instar

Single generation per year in the UK. Larval development occurs within and on rushes (Juncus spp.).

Final instar larvae switch from internal feeding within rush foliage to external feeding.

Genome sequenced as part of the Darwin Tree of Life project (haploid assembly 272.06 Mb in 6 chromosomal pseudomolecules; mitochondrial genome 30.01 kb). No significant economic or medical importance documented.

• Other Eutomostethus speciesSimilar size and general morphology; distinguished by specific color pattern of black thorax with orange-yellow marked abdomen and association with Juncus hosts
• Other Blennocampinae sawfliesShare family and subfamily characteristics; separated by host plant specificity and abdominal coloration pattern

• sawfly
• Tenthredinidae
• parthenogenesis
• rush feeder
• Darwin Tree of Life
• genome sequenced

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• The genome sequence of the Tenthredid wasp, Eutomostethus luteiventris (Klug, 1816) (Hymenoptera: Tenthredinidae).