It is expected that soybean (Glycine max [L.] Merr.) cultivars resistant to various insect pests shall play an important role in integrated pest management programs. Certain soybean cultivars have been shown to possess resistance to Mexican bean beetle (Epilachna varivestis Mulsant) (Van Duyn et al., 1971, 1972), bean leaf beetle (Cerotoma trifurcata Foster), striped blister beetle (Eplicanta vittata Fabricius) (Clark et al., 1972) and corn earworm (Heliothis zea Boddie) for leaf feeding (Beland and Hatchett, 1976; Joshi and Wutoh, 1976; Joshi, 1977; Hatchett et al., 1976). It has been suggested that 2 to 3 weeks age difference has considerable effect on the expression of antibiosis to corn earworm as expressed by low larval weight and higher larval mortality in cases of resistant genotypes.