Calosoma (Chrysostigma) obsoletum Say, 1823

Calosoma obsoleta Say, 1823: 149 (described from Arkansas river, Colorado; neotype in Museum of Comparative Zoology, Harvard University, Cambridge, Ma)
Calosoma luxatum Dejean, 1825: 196
Calosoma indistictum LeConte, 1845: 208 (described from USA)
Calosoma obsoleta microsticta Casey, 1897: 345 (described from Fort Wingate, New Mexico; syntype in National Museum of Natural History, Washington)
Calosoma (Carabosoma) obsoletum Breuning, 1928: 110
Calallisthenes (Chrysostigma) obsoletum Lapouge, 1931: 381
Calhrysostigma obsoletum Jeannel, 1940: 167
Calosoma (Chrysostigma) obsoletum Gidaspow, 1959: 267
Calallisthenes (Chrysostigma) obsoletus Erwin, 2007: 80

Length 17-25mm. C. obsoletum has pronotum distinctly and evenly punctate with rounded rear lobes, just protruding from the base The elytra relatively longer with almost flat but still recognizable sculpture. All the intervals are a little convex and scaly. The foveae on the primary ones are not wider than the intervals themselves. The color of upper body is black, non-metallic.
C. obsoletum is present in all the western United States and in the south-west of Canada: Alberta, Manitoba and Saskatchawan (Bousquet, 2012: 242).

Examined specimens
Canada. Alberta: Empress (UASM)
United States. Colorado: Denver county (UASM); Kansas: Atchison (SB); Nebraska: Custer County (EM), Mitchell (EM); New Mexico: Water Canyon (Snow, 1881: 39), McKinley county (UASM).

Notes:Winged. It is found from lowlands to uplands, from up to 2100m altitude, on praries, open ground tilled fields. It is crespucular as well nocturnal and some time attracted to light at night, taking refuge under stones and various shelters in daytime. Adult feed prefereably on caterpillars of the moth Hemileuca oliviae and the larvae on the pupa of the same species (Burgess & Collins 1917: 87). Adults individuals have been found active from April to November, and overwintering in small cavities in the ground.
A brief description of larval stages can be found in Burgess & Collins (1917: 89).

Calosoma (Chrysostigma) obsoletum ♂ Say, 1823
United States: Texas, Denton county,
United States: Kansas, Atchinson, City streets, at light; JW McReynolds; May, 18, 56
Calosoma (Chrysostigma) obsoletum ♀ Say, 1823
United States: Kansas, Atchinson, City streets, at light; JW McReynolds; May, 12, 56