Elcar (Heliothis nuclear polyhedrosis virus) was applied to corn through center pivot irrigation systems to control larvae of Helicoverpa zea. Screen cages were used to capture moths as they emerged from the soil, and the projected number of moths produced per acre was calculated. The projected number of bollworm moths produced per acre in untreated plots was 1,518 in 1991 and 2,698 in 1992. The reduction in number of moths produced varied from 25 to 100% depending on timing and rate of application. Elcar was most effective in reducing the number of moths produced when the corn was treated once during the tassel stage and three times during the silking stage.