Rhopalum (Corynopus) coarctatum



Conservation status

Not Assessed

Species Biology


  • Body length: 4-6mm
  • Head, thorax and abdomen black in colour
  • Legs black and yellow in colour, hindleg with small reddish patch
  • Petiole (narrow waist section behind thorax) with small enlargement
  • Square-ish head shape and narrow body
  • Could be confused with Rhopalum clavipes, but it lacks the reddish abdomen. Close-up views under a microscope and use of specialist keys will usually be required for identification


Irish records suggest some association with wetland habitats, such as riverbanks, lakesides, fens and reedbeds.

Flight period

Univoltine between early June-late August.

Nesting biology

Not known in Ireland, but suspected to use hollow stems and possibly deadwood. Multiple cells will be constructed in each nest, which will be deposited with paralysed flies on which the  larvae will feed on before pupating and emerging as adults the following year.

Flowers visited

None known in Ireland.

Similar species

  • Other Rhopalum species
  • Other small, black digger wasps
  • Small Ichneumon species


World distribution(GBIF)

Temporal change

Records submitted to Data Centre in 2024

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