A low maintenance annual, the petunia produces non-stop flowers from spring to fall in a wide array of colors. During the months of June and July, the petunia often falls victim to the budworm caterpillar (Helicoverpa virescens).
The greenish budworm attacks the flower and flower buds of the petunia. The flower’s buds often fail to bloom and drop from the plant. Buds that do produce flowers appear frayed and chewed. The damage can become quite severe and the plant may succumb.
The budworm is the caterpillar of the budworm moth. The budworm moth is a light green and brown moth that measures 1 1/2 inches in length. The budworm larvae display shades of red, brown and green. Each caterpillar feeds voraciously for approximately one month before pupating in the soil into an adult.
Check the petunia daily at dusk for budworms, according to the Colorado State University. Pick the caterpillars from the plant and destroy them. Application of synthetic pyrethrins can also help gain control of the insects.