Stink bug adults are green or brown, flat-topped insects that are about 1/2 inch long. They are shield-shaped, with a large triangle on their backs. They lay their eggs in clusters on the leaves. Nymphs are rounded, variously colored, and look little like the adults until they approach maturity.

Stink bugs are a contaminant in harvested peas because the nymphs are the correct size and shape to be indistinguishable from the peas by mechanical harvesting equipment.  

Life Cycle

Several species of stink bugs infest a variety of plants in Illinois.  All overwinter as adults, especially under boards, logs, and leaf litter.  In the spring and early summer, adults become active, and females lay barrel-shaped eggs neatly arranged in small clusters on leaves.  Each female may lay hundreds of eggs.  Immature stink bugs (nymphs) develop through 5 stages over a 5- to 7-week period before reaching the adult stage.  Some species complete two successive generations in one year, others only one.  Numbers of adults are greatest from August through October.       

Management

• Use a sweep net to scout pea fields within a few days of harvest to determine if a problem with stink bugs exists. If necessary, use an insecticide with a short preharvest interval to control the stink bugs.
• An alternative to an insecticide application is to adjust blowers and air cleaners within the processing plant to effectively remove the bugs. 
• Services include plant and insect identification, diagnosis of disease, insect, weed and chemical injury (chemical injury on field crops only), nematode assays, and help with nutrient related problems, as well as recommendations involving these diagnoses. Microscopic examinations, laboratory culturing, virus assays, and nematode assays are some of the techniques used in the clinic.