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Guides
Calosoma externum
Narrow Searcher Beetle, Churchyard Caterpillar Hunter
Calosoma externum is a large predatory ground beetle in the family Carabidae, commonly known as the narrow searcher beetle or churchyard caterpillar hunter. First described by Thomas Say in 1823, this species is notable for its arboreal hunting behavior, ascending trees to prey on caterpillars. Adults reach 28–35 mm in length and are distinguished by their black bodies with bluish marginal reflections. The species occurs across much of the United States and into southern Canada.