First generation larvae of Heliothis zea (Boddie) and H. virescens (F.) were collected in wild geranium, Geranium dissectum L. and G. carolinianum L. in Washington County, Miss. during May in 1988. These larvae were reared on artificial diet and tested as adults using a vial bioassay for resistance to the synthetic pyrethroid, cypermethrin. Survival of H. zea moths tested at the rate of 10 ug/vial of cypermethrin was 2.9 and 5.6% for males and females, respectively. Resistance occurred more frequently in H. virescens than in H. zea moths and 26 and 41.5% of the H. virescens males and females, respectively, tested survived the 10 ug/vial rate of cypermethrin. The F₁ male and female H. virescens moths that survived the 10 ug/vial rate of cypermethrin were mated, and the resulting F₂ larvae were tested as third instar larvae for pyrethroid resistance using a cotton terminal bud bioassay. In the cotton terminal bud bioassay 65% of the F₂ larvae tested survived an application of cypermethrin applied at its highest recommended field rate (0.09 kg [AI]/ha). These data indicate that if the F₁ adult and F₂ larval populations in cotton in June were treated with pyrethroids, control problems would be more likely to occur later in the growing season.