Calosoma (Callitropa) externum (Say, 1823)

Carabus externus Say, 1823: 150 (neotype: Little Rock Ark(ansas); Museum of Comparative Zoology, Harvard University, Cambridge, Ma)
Calosoma longipenne Dejean, 1831: 568 (type: Amérique Boréale; Muséum National d'Histoire Naturelle, Paris)
Calosoma (Callitropa) externum Breuning, 1928: 116
Callitropa (s. str.) externa Lapouge, 1932: 384
Callitropa (s. str.) externum Jeannel, 1940: 213
Calosoma (Callitropa) externum Gidaspow, 1959: 273
Calosoma (Callitropa) externum Erwin, 2007: 92


Length 28-35 mm. C. externum, like the other species collected by Jeannel (1940) in the subgenus Callitropa (s. str.), has an elongated shape, and it is winged; therefore its metaepisterna are longer than wide. It differs, however, from the others because its elytra are clearly striated, with intervals that are faintly scaly. The colour of the upper body is black with bluish reflections on the margins.
C. externum occupies almost the entire United States, even though it seems more common in the eastern part. It has been found occasionally in Canada (northern shores of Lake Erie), but it does not seem to be a permanent resident (Lindroth, 1961: 49). Towards south it can reach Mexico (Nuevo Leon), where a dead specimen was recently (sept. 2016) discovered and photographed (inaturalist.org).

Examined specimens and literature’s data
Canada. Ontario: Turk Point, long Point, Point Pelee National Park (Lindroth, 1961: 49)
Mexico. Nuevo Leon: Monterrey, Cerro de la Silla (inaturalist.org/obs. 4027470)
United States. Alabama: Tuscaloosa county (UASM); Arkansas: Little Rock (neotype, MCZ); Connecticut (Burgess & Collins, 1917: 21); Delaware: Newark (www.gbif.org); Distr of Columbia: Washington (Burgess & Collins, 1917: 21); Georgia (Burgess & Collins, 1917: 21); Illinois: Chicago (SB), Dixon Springs (http://bugguide.net/); Iowa (Burgess & Collins, 1917: 21); Kansas: Atkinson (SB), Salem, Turnpike, Wellington (www.gbif.org), Shawnee county (http://bugguide.net/), Sumner county (http://madrean.org/); Kentucky: Christian county (UASM), Warren county (http://bugguide.net/); Maryland Cove Point (http://www.covepoint-trust.org/); Massachusetts (Breuning, 1928a: 117); Michigan: Third Sister Lake (www.gbif.org); Minnesota: Olmsted co., Ramsey co. (St. Paul), Houston co. (Gandhi & al,, 2005: 922); Missouri: Vernon county (SB), St. Charles county, Stoddard county (http://bugguide.net/), Jefferson county (UASM); Nebraska: Lancaster county (http://bugguide.net/); Nevada: Vernon county (UASM); New York (Burgess & Collins, 1917: 21); North Carolina: Durham county (http://bugguide.net/), Raleigh (SB); Ohio: Delaware county, Franklin county (www.gbif.org); Oklahoma: Stillwater (Burgess & Collins, 1917: 21), Norman, Johnston (www.gbif.org); Oregon: Enterprise (www.gbif.org); Pennsylvania (Burgess & Collins, 1917: 21); South Carolina (Burgess & Collins, 1917: 21); Tennessee Great Smoky Mountains N.P. (www.gbif.org), Obion county (UASM); Texas: Palo Pinto county (http://bugguide.net/), Live Oak county (EM), Sherman (www.gbif.org); Wisconsin: Columbia, Dane, La Crosse (Messer, 2009: 33).

Notes: Winged, often attracted to light at night. It lives in grassland and fallow land, in lowlands and midlands up to an altitude of 1000m. Occasionally, has been noted climbing trees, but probably it secures most of its food near the ground. It feeds on the grasshopper Melanopus spretus, the beetles (Melonthinae) of genus Lachnosterna, and various caterpillars as Cirphis unipunctata, Malacosoma americanum and Lymantria dispar. The adults happen to overwinter in the soil (Burgess & Collins, 1917: 22). Active individuals have been found from May to October, according to data of the examined materials, but also from April to November, according to Larochelle & Larivière (2003: 177).
The description of larva in all stages and pupa has been given by Burgess & Collins (1917: 23).

Calosoma (Callitropa) externum
(Say, 1823)
Amérique Boréale
(holotype of Calosoma longipenne Dejean, 1831)
(coll. Muséum National d'Histoire Naturelle, Paris)
Calosoma (Callitropa) externum
(Say, 1823)
United States, Kansas: Atkinson, city streets,
at light, 16.V.1956, JW MacReynolds
Calosoma (Callitropa) externum
(Say, 1823)
United States, North Carolina:Raleigh,
10.X.1948, E Thompson

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