The transmission of a nuclear polyhedrosis virus (NPV) from generation to generation was studied in Spodoptera litura (F.). NPV-infected adults were produced by feeding 5th instar larvae with sub-normal concentration of NPV. Egg and larval mortality was observed in the progeny from infected adults, the transmission being transovum and transovarial. The healthy adults were able to transmit the NPV to their progeny by egg surface coating when fed with NPV orally, more so when both the sexes were fed. The larval mortality was more in the case of eggs laid on the first day and declined in the case of second and third day laid eggs.