Four-lined plant bugs are sap-feeding insects that can severely damage over 200 species of perennial plants, especially herbs. A dark brown to black, 1/16- inch diameter spot appears at each feeding site. Saliva injected as the insects feed kill surrounding tissue, which eventually dies and drops, leaving small holes. The damage is most intense on the new growth (Figure 1).
Adults are yellow-green with 4 black stripes running along the back. They are good fliers, moving from plant to plant. The immature nymphal stage is bright red to orange with black markings. They cannot fly so they remain on plants and cause pockets of extensive damage.
- A floating row cover can be used as a physical barrier.
- Insecticidal soap or pyrethrins can be used as contact sprays with some success.
- The insect must be hit with the spray and repeated applications are needed.
By Lee Townsend, Extension Entomologist