An Iridescent Purple Carabid (Ground Beetle) Found in Field Crops of Kentucky

Beetles have hard forewings that may partially or totally cover their membranous flight wings. These wings can be dull, very colorful, or covered with small hairs (as in Dectes stem borer). Many have a bright metallic color, and in many cases, these beetles are geographically associated with their abundances in rainforests or tropical areas rather than temperate zones. However, in Kentucky there are many colorful beetles that live in forests or on agricultural lands. Many members of the ground beetles or species in the Carabidae family are known to display metallic colorations (see the Tiger beetles article) and feed on other insects.

Since 2018, we have been studying the presence of ground beetles in Kentucky wheat, corn, and soybean fields. However, a large (1 inch in length) colorful species had not been found until last week, when for the first time, we observed a couple of beetles with an intense purple iridescent color on the hard wings, dorsum, and head (Figures 1 and 2). This species is identified as Dicaelus purpuratus, which can be found from Florida to Ontario, Canada. Although the Entomological Society of America has not provided an official common name yet, beetles of this specific group can be found elsewhere and classified as notched-mouth ground beetles.

Not much is known about the biology, habits, or phenology of this species, but it has powerful mandibles that are specially adapted for breaking the shells of snails, which may be its primary prey. Coincidentally, the field where we found this beetle has a historical abundance of snails. ∆

Raul T. Villanueva, Entomology Extension Specialist, Armando Falcon-Brindis, Research Associate Entomology, and Zenaida Viloria Research Analyst, University of Kentucky