Field control failures in populations of tobacco budworms (Heliothis virescens (F.)) occurred in 1992 in the Lower Rio Grande Valley. El Nino weather phenomenons and poor timing of pyrethroid use were speculated as the cause of the above normal infestation and field control failure rates. Adult vial tests for cypermethrin susceptibility showed very low mortalities and high LC 50 values on tobacco budworms in 1992. However, topical application of cypermethrin on third instar larvae reared in the laboratory from field collected specimens indicated high levels of mortality by 72 hours post treatment, but not in 24 or 48 hours.