Caring for petunias Caring for petunias Caring for petunias Cutworms and caterpillars are the prime insect attackers of petunia plants and your primary concern when caring for petunia plants. Cutworms are 1.5 inches to 2 inches long and may be gray, brown or black. Caterpillars may be smooth, or hairy and grow up to 4 inches in length. Cutworms coil when disturbed, and are usually found about 2 inches deep in the soil of damaged plants near the base. The most likely pests of young petunias are the surface-feeding cutworms and climbing cutworms.
Caterpillars begin their damage as adult female moths or butterflies, which lay eggs on plants.
However, larvae, and mature caterpillars do their part as well. Climbing cutworms shear leaves off older plants as well as young ones. Just one surface-feeding cutworm can sever the stems of many young plants in an evening. Both hide in the soil during daylight hours and feed only after sundown. Once the cutworm matures, its adult form is that of a dark, night-flying moth with stripes or bands on the forewings.