In the past week, we’ve noticed a dramatic jump in the number of hornworm caterpillars and eggs in our test plots at the Upper Coastal Plain Research Station near Rocky Mount.
A healthy tobacco hornworm in Rocky Mount, NC. Note red horn, which distinguishes this caterpillar from tomato hornworms. Photo: Demetri Tsiolkas
As these caterpillars can eat a lot of tobacco in a short period of time, once scouting has revealed populations above threshold, growers should take quick action to prevent defoliation. Threshold is one hornworm per ten plants.
Horworm damage can be extensive if left unchecked. Photo via Sterling Southern, professor emeritus, NC State University Department of Entomology
Growers and scouts who are fortunate enough to see parasitized hornworms, like the one in the picture below, should keep in mind that visibly parasitized hornworms feed slowly and die before completing development. When scouting to determine if hornworms are at threshold, 5 parasitized hornworms = 1 healthy hornworm.
This hornworm was parasitized by braconid wasps. Although the white bodies look like “eggs”, they are actually tiny wasp cocoons. Photo: Demetri Tsiolkas
Written by: Aurora Toennisson