Diseases –In mid- to late-season, naturally occurring diseases (fungi, bacteria, and viruses) of soybean insect pests can be important in control. A full leaf canopy, along with certain environmental conditions, apparently produces a microclimate favorable for insect disease development. Diseases often control armyworms, velvetbean caterpillars, green cloverworms, and soybean loopers. After diseased larvae have died, they may have a whitish moldlike growth covering their body surface, a black coloration with their bodies filled with fluid, or a near normal appearance (depending on the disease).
The presence of diseased worms indicates the population is being reduced naturally. When you find diseased larvae, withhold treatment for a few days to see if the disease will spread to a level that can control the population.
Predators and Parasites – Beneficial predators and parasites are very important in reducing the number of early-season insect pests. For this reason you should protect them to have their full benefit. Predators and parasites can often keep pests from reaching treatable levels. Some early-season insecticide applications to soybeans can severely reduce predators and parasites. Regular scouting of fields is essential in detecting insect pests as well as beneficials.