Chlorops strigulus (Fabricius, 1794)
on Brachypodium

Brachypodium sylvaticum, Belgium, prov. Namur, Andenne, carrière du Bois de Tiarmont © Jean Yves Baugnée

the gall causer, reared male
Brachypodium sylvaticum, France, dép Sarthe, Vancé © Sébastien Carbonnelle. Probably this vacated gall was equally caused by some Chlorops.
host plants
Poaceae, monophagous (?)
Brachypodium pinnatum, retusum, sylvaticum.
synonyms
Chlorops cingulata Meigen, 1830.
note
Galls of this type generally are referred to Chlorops pumilionis, but in fact a number of species are involved, that can only be identified on the basis of reared material. C. strigulus is characterised by the large frontal triangle, far drawn out anteriorly and with deep grooves at either side, and by the white arista (JY Baugnée).
references
Spooner & Bowdrey (2012a), Dauphin & Aniotsbehere (1997a), Houard (1908a), Nartshuk (2006a), Roskam (2019a).