Nysius is a very difficult genus, and most species are hard to identify, requiring close examination of a specimen.  N graminicola is medium-sized, usually between 4.0 and 4.5 mm; males are smaller and some larger females at over 5mm have been recorded in Leicestershire. It has a dark ring at the base of the 2nd antennal segment.  The 1st hind tarsal segment is longer than the combined length of the 2nd and 3rd segments and claws - sometimes only slightly.  The matt area of the metapleuron is smaller than N senecionis and does not include the longitudinal groove in the uper part of the metapleuron.  For confirmation, check that the bucculae (the sheath of the rostrum) is tapering to the rear, and not truncate; and check that the male genital capsule has teeth on the margin of the aperture. 

other Nysius, especially the common N senecionis, which has 1st hind tarsal segment shorter than the combined length of the 2nd and 3rd segments and claws. 

• dark ring at base of 2nd antennal segment
• 1st hind tarsal segment is longer than the combined length of the 2nd and 3rd segments and claws
• bucculae tapering
• male genital segment with teeth on the margins of the aperture

Detailed photos of a specimen needed, showing antennae, metapleuron and hind tarsi.  If possible, photograph or describe bucculae and aperture of male genital segment .  Note size, and sex.

RDB3 (ref.: British Heteroptera checklist 2021 on British Bugs website)

Rarely recorded.  There was an influx of this species towards the end of the very hot and dry summer of 2026

https://www.britishbugs.org.uk/heteroptera/Lygaeidae/Nysius_senecionis.html  (this includes a note regarding N graminicola)

Kirby, P. (2015)  British Heteroptera: Keys to terrestrial families other than Miridae (2nd draft).  Unpublished

Dolling, W.R. (2003)  Identification of Nysius — again. Het News 2   https://www.britishbugs.org.uk/HetNews/Issue%202_Autumn%202003_397Kb.pdf