Black and yellow Vespula nectaring on Sisymbrium loeselii. Stream floodplain disturbed in winter 2020-2021 by heavy equipment during stream restoration work. Large patches of bare ground, stands of exotic perennial grasses re-establishing, large patches of Chenopodium simplex and C. berlandieri with many ripe seeds, and patches of still-flowering Sisymbrium loeselii. Few other plants still flowering. Partly sunny afternoon, wind varying from calm to light breeze, good air quality, 55 F to 62 F.

Elevation ca 4000 feet. Disturbed riparian corridor on stream restoration site within a patchwork of native and non-native grassland.

Characters indicating Vespula include the notched apex of the Clypeus (=Vespinae), then the very short distance between eyes and mandibles to eliminate Dolichovespula, and the head not widening behind the eyes to eliminate Vespa. Within Vespula, the combination of black markings on terga 1-4, yellow longitudinal markings on scutum not complete, and eye with a complete dorsal yellow margin + T1 with a black diamond-shaped medial marking pointed to V. pensylvanica (based on Kimsey and Carpenter 2012).