Fiery Searcher

Calosoma scrutator (Fabricius)

Carabus scrutator Fabricius, 1775:239. [Holotype, sex unknown, USA, Virginia (Banks) (BMNH).]

DIAGNOSTIC COMBINATION.—These large, metallic blue and green beetles with broad, inflated elytra are easily recognized on color alone, differing from members of C. aurocinctum by the former’s bicolored pronotum. Color and luster: black, with golden green spots near eyes, pronotum with dark blue or black disc and golden green or purplish margins, elytra metallic or dark green, venter with blue luster, appendages brown with blue luster. Form: size large, head and pronotum narrow relative to broadly inflated elytra; eyes large and prominent Structure: pronotum with sides evenly arcuate, small rounded hind angles, without basal setae; elytra serrate near humerus, with striatopunctate intemeurs, punctures connected by scaly cross lines, intervals convex; middle tibia markedly arcuate, in male with dense brush of reddish setae; male foretarsi with four dilated articles, each with spongy pubescence beneath. ABL = 25.0 to 35.0 mm; TW = 11.0 to 16.0 mm (from Gidaspow, 1959).

GEOGRAPHICAL DISTRIBUTION.—Although I have not seen any specimens, Gidaspow (1959, 1963) indicates that these beetles were found in Guatemala and Venezuela. They are relatively common also in Mexico.

NATURAL HISTORY.—Lindroth (1960) indicates that these beetles are found in hardwood forests where they feed on tent and noctuid caterpillars. They are fully winged and fly to lights at night.

MATERIAL EXAMINED.—Type (see above) and 20 specimens from the eastern United States.

Calosoma scrutator, also known as the fiery searcher and caterpillar hunter, is a species of ground beetle belonging to the genus Calosoma, subgenus Acalosoma. This beetle can be as large as 35 millimetres (1.4 in) long. The distribution of this species is relatively widespread, but it is nonetheless uncommon in North America. The adult beetle is known to excrete a foul-smelling oil when it is handled. The oil has been described as smelling similar to rotten milk or rancid olive oil.