Eastern tent caterpillars in Central Kentucky are mature, have dispersed from trees, and are on the move, leading experts to advise horse farm managers to move pregnant mares, if practical, to avoid contact with the crawling caterpillars.

Lee Townsend, MS, PhD, University of Kentucky (UK) College of Agriculture, Food, and Environment extension entomologist, indicated caterpillar populations are up in Central Kentucky this year.

“Mature eastern tent caterpillars leave trees in search of protected pupation sites, where they will spin cocoons and transform into adults; this dispersal is a normal part of their life cycle,” Townsend said. “These wandering caterpillars may move several hundred feet from the trees where they developed. The direction of travel tends to be random and directly related to air and ground temperatures. Movement will be slower when temperatures are cool and faster when they are warm. The caterpillars wander for a period of time until internal hormones signal that it is time to stop and pupate.”

Townsend said wandering caterpillars orient to dark, vertical objects so they will often climb tree trunks and fence posts. Check fence posts and rails to monitor caterpillar movement. If caterpillars are around, they are likely to be on these objects. Activity is expected for the next two weeks