Several newly developed lepidopteran cell lines derived from the preemergent pupal fat-body and ovarian tissues of the cabbage looper, Trichoplusia ni (Hübner), the corn earworm, Heliothis zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith), supported replication of their homologous nuclear-polyhedrosis viruses. In addition, the multiple-embedded cabbage looper nuclear-polyhedrosis virus infected the cell lines from the other 2 insect species. New enriched media and culture techniques increased cell growth and production of virus polyhedra.