Eggs and each instar of the cabbage looper, Trichoplusia ni , were introduced weekly into Missouri soybeans to assess natural mortality. Percent recovery 24 h later demonstrated high mortality due to predation, which peaked between flowering and pod fill of the soybeans. First and 2nd instars were most susceptible, with seasonal average mortalities of 51.9 and 43.5%, respectively; 3rd and 4th instars were least susceptible, with averages of 30.1 and 25.0%, whereas mortality of 5th instars, 34.9%, was intermediate. Few of the recovered eggs or larvae were parasitized, but disease caused significant mortality of larvae, due especially to a late-season epizootic of the entomopathogenic fungus, Nomuraea rileyi (Farlow) Samson. Parasitism, mostly by Rogas nolophanae and Cotesia marginiventris peaked at 36.3% in July. Mortality due to disease reached a peak of 70.0% late in the season, again due to the epizootic of N. rileyi . Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Diseases and disorders; Diseases; Microbial diseases; Ecology; Population dynamics; Habitat; Terrestrial habitat; Land and freshwater zones; Nearctic region; North America; USA Plathypena scabra (Noctuidae); Hymenopteran parasites; Cotesia marginiventris & Rogas nolophane; Bacterial diseases; Bacillus thuringiensis & Nomuraea rileyi; Larva mortality, soybean plants; Mortality; Causes, eggs & larvae; Plant and vegetation habitats; Soybean fields, mortality of eggs & larvae; Missouri; Columbia area; Mortality causes, eggs & larvae in soybean fields Trichoplusia ni (Noctuidae); Bacterial diseases; Bacillus thuringiensis & Nomuraea rileyi; Mortality; Causes, eggs & larvae; Predators; Podisus maculiventris (Hemiptera); Larva mortality, soybean plants; Plant and vegetation habitats; Soybean fields, mortality of eggs & larvae; Missouri; Columbia area; Mortality causes, eggs & larvae in soybean fields Cotesia marginiventris; Rogas nolophane (Braconidae ); Lepidopteran hosts; Plathypena scabra; Host larva mortality; Missouri; Columbia area; Lepidopteran host larval mortality, soybean fields Podisus maculiventris (Pentatomidae); Prey; Trichoplusia ni (Lepidoptera); Prey mortality, eggs & larvae; Missouri; Columbia area; Lepidopteran prey mortality