Monday, June 20, 2011
This large ground beetle is called a Narrow Searcher (Calosoma externum) and they are found throughout Eastern North America in forested areas and nearby grasslands. We commonly find them under rock piles on one farm we own in the river bluffs. They also go by the common name of Caterpillar Hunter which eludes to their diet of primarily caterpillars. This preference for caterpillars makes them beneficial to agriculture because of the large amount of harmful moth caterpillars they consume. The caterpillars frequently climb trees in search of their prey. Look out tent caterpillars!
Most species within this genus are all black, with a few exceptions that are metallic in coloration. This particular species is black with metallic purplish-blue wing and pronotum margins. All species within this genus produce a foul smelling chemical from glands near the tip of their abdomen. This is a defense mechanism designed to thwart predators.
These beetles hibernate throughout the cold months and become active again in the spring. During the hottest parts of the summer months these beetles may go unseen and return again with autumns cooler temperatures.