Issue 5, May 21, 2010
Fourlined plant bug is a pest on mint, lavendar, sage, artemisia, sunflower, and other herbs. It is particlarly a problem on mint, being its most severe pest. Damage appears as contorted leaves with brown to black spots. Frequently, the spots are numerous enough to coalesce into large areas that may consume half or more of the leaf.
Close observation in spring reveals the red nymphs hiding in the leaf axils. At this time they are about one-eighth inch long, but will continue to feed and grow to about one-quarter inch long. They will then molt into the one-quarter inch long adults that are greenish-yellow with four black stripes running the length of the body. The adults are very active runners and fly readily when disturbed. The adults are obvious on the plants because they do not hide. By the end of June, they will have mated and inserted their eggs into plant stems where they will remain until hatching next spring. Because the eggs overwinter in the stems, removing plant debris in early spring should reduce their numbers.--Phil Nixon