The persistence of a nuclear polyhedrosis virus (NPV) on soybean after death and lysis of NPV-killed (AgNPV)Anticarsia gemmatalis(Hübner) larvae on the plants was examined. Bioassays of virus on leaflets (which had no direct contact with the diseased larvae) collected from these plants showed that AgNPV activity persisted on the plants for the entire 7-wk test period, with up to 62.7% larval mortality in bioassays conducted after the seventh week. Regardless of the canopy location (higher or lower) of the virus-killed cadavers, AgNPV activity was higher on the leaflets collected from the lower canopy after 2 wk and remained so for the duration of the test. This may be related to movement of AgNPV into the lower canopy by rainfall and wind where it can be better shielded from sunlight inactivation by the foliage. A separate test was conducted in which uninfected larvae were caged for 5 d on soybeans at weekly intervals after death of AgNPV-infected larvae. The mean larval mortality during the 4-wk period of this test was higher in treatments in which AgNPV-killed cadavers had died in the upper canopy. This may be explained by the preference of the uninfected larvae for the upper canopy.