Our insect of the week (November 25, 2024) is Calosoma scrutator (also known as the caterpillar hunter. [COLEOPTERA: Carabidae]. This beetle is relatively common across much of North America. Adults often excrete a foul smelling oil when handled (smells like rancid olive oil). This specimen was collected by our former member Gordon Adams in Peoria County in 1964.

As their common name implies, adults and larvae prey on caterpillars (often Noctuidae and Geometridae). The life cycle is one year, but some adults have been observed overwintering and may live up to three years. Adults are attracted to lights at night, but do not frequently fly. They have been recorded climbing trees and shrubs in search of prey.

Eggs are laid individually during early summar months. They hatch within 3 – 15 days (depending on temperature). Larvae develop through three instars. It can take about one month before pupation. The pupal stage is passed in an earthen cavity constructed by the final instar larva. Yes, adults readily bite. Wonder how I know that?

Here are views of the beetle (top is dorsal view, middle is lateral view, bottom is frontal view).