Invasion of the Beetles

Gail Ruhl, Plant Disease Diagnostician, Purdue University

Chris Parker, Extension Educator in Morgan County, reports that their local high school had literally thousands of these Caterpillar Hunters in and around the building Monday morning. The warm weekend prompted the emergence of this species of beneficial ground beetle, Calosoma scrutator, which generally feeds at night and hides during the day.

This beetle climbs trees in search of caterpillar prey.  The beetle emits an odor to ward off predators and intruding humans and is also ‘equipped’ with a hefty set of mandibles which can deliver an unwelcome nip to imprudent handlers.  Although the beetles are active from May to November, it is reported that they seem to be especially numerous in May after trees are fully leaved out and while the spring flush of caterpillars is ravaging the foliage. The Caterpillar Hunter feeds on tent caterpillars, gypsy moth caterpillars and pupae, and other forest caterpillars and is strongly attracted to lights.

Links: Clemson University; Ohio State University Extension Fact Sheet

Related News: Green, stinky and harmless - IndyStar.com, by Dan McFeely - May 12, 2005

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.

Information listed is valid only for the state of Indiana.

Click image to enlarge

Calosoma scrutator

Photo courtesy of
University of Arkansas

Calosoma scrutator around buildings in Martinsville, IN

Photo courtesy of Chris Parker