Hornworms are active now and can be found feeding on solanaceous plants (tomatoes, potatoes, tobacco). This is the first of two generations that normally occur each year in Kentucky. While the first generation is usually much smaller than the second, plants are smaller so just a few hornworms can be very destructive.
Hornworm moths lay single eggs on the undersides of leaves in the upper third of plants. These insects hang and feed under leaves (Figure 1); irregular holes appear as they feed. Large worms can eat entire leaves, causing extensive damage very quickly.
- Bt insecticide is a selective means of controlling caterpillars with minimal impact on beneficial species. However, Bt products are most effective against small worms and these products are degraded relatively quickly by sunlight, so the length of protection is short.
- Spinosad products also provide some selective control with a longer residual life.
By Lee Townsend, Extension Entomologist