A new multiply embedded nuclear polyhedrosis virus, AFMNPV, isolated from the celery looper (Anagrapha falcifera (Kirby)) was shown to be highly infectious to both Helicoverpa zea and Heliothis virescens in laboratory tests. In addition, AFMNPV infects many other lepidopterous pests of cotton. A small greenhouse test on cotton plants in 1990 confirmed the susceptibility of the above species and also Spodoptera exigua and Trichoplusia ni. Laboratory tests also confirmed the susceptibility-of Pectinophora gossypiella. Based on these tests, ARS entered into a Cooperative Research and Development Agreement with Sandoz Agro, Inc. to conduct further studies on the efficacy of the virus for the above mentioned species. In 1990 small scale field tests were conducted and showed that H. zea and H. virescens were approximately equal in susceptibility to residues of AFMNPV on cotton leaves at doses ranging from the equivalent of 4 x 10" to 4 x 10" polyhedra (PIB)/acre. However, by day 7 less than 50% of the original activity towards H. zea was left on the leaves. Residues of application of 4 x 10(12) and 4 x 10(11) PIB/acre caused less than 50% mortality 3 days after application. In 1991 similar tests were conducted to compare AFMNPV and a commercial preparation of the Heliothis virus (ELCAR^®). Methods were similar to 1990 tests. Only H. zea larvae were used in these tests as they are slightly less susceptible to AFMNPV. In general, less than 50% of the activity was left after 7 days for all doses tested. Results of these studies show that AFMNPV has potential as a microbial control agent for control of both species. However, field persistence, application rates and technology and formulation must be addressed.