Baseline data were collected on the natural occurrence of the nuclear polyhedrosis virus ofAnticarsia gemmatalis(Hübner) in Louisiana and Texas in preparation for future attempts at introduction and establishment of the virus. The virus was not detected inA. gemmatalislarvae collected from 12 sites in Louisiana or 2 sites in Texas (total n = 3,391) on numerous sampling dates in 1989 and 1990. The only exception was a possible, light infection in one insect collected at a site that had been sprayed withA. gemmatalisnuclear polyhedrosis virus during 1979–1981. The virus was not detected in any of 24 soil samples collected from two sites in Louisiana in spite of detection of as few as 15.9 polyhedral inclusion bodies per g of soil in positive controls. Attempts were made in the laboratory to determine whether the viral infections could persist in adults and be transmitted to the progeny. TheA. gemmatalisnuclear polyhedrosis virus was not so transmitted, even thoughSpodoptera frugiperda(J. E. Smith) adults, the positive control, transmitted their homologous nuclear polyhedrosis virus to 14.3% of their progeny. It is hypothesized that a lack of vertical transmission is the reason that theA. gemmatalisnuclear polyhedrosis virus apparently is not indigenous to the United States.