Results are reported from the third year of a 3-year project aimed at examining the feasibility of calibrating the standard 75-50 cone-shaped Heliothis spp. pheromone trap. Replicating the previous two years (1987-88), four traps/spp were deployed around four, 20-acre plots in cultivated cotton. Traps were monitored daily, nighttime observations of moth activity were conducted four nights/week, and whole plants were inspected for eggs and larvae following nighttime sampling. The proportion of H. zea among immatures collected was higher than in previous years (ca. 18% vs <5% in 1987-88) ; however, H. virescens was still the predominant Heliothis species ovipositing (82%) on cotton and captured by hand (84%) in the area sampled, and in trap collections (53%) over the season. For H. virescens, as in 1987-88, the correlation between moths captured by hand at night and egg numbers was highly significant (P<0.0001), and the highest correlation (P<0.0019) between egg counts and trap captures occurs with a time lag of ca. 2 days, as in 1988 vs 4 days in 1987. For H. zea, no correlation was found between hand-captures and egg counts, and the highest correlation (P<0.0008) between egg and trap counts occurred with traps peaking 24-48 hours prior to the oviposition peak; low incidence of oviposition in cotton by zea in 1987-88 precluded comparisons. Impacts of abiotic factors on the system, particularly temperatures, precipitation, plant density, and insecticide applications, are addressed.