Comparison of daily and seasonal values of whole-body lipid, ovarian development, and two mating parameters (percentage of mating and number of spermatophores) were examined in adult soybean loopers,Pseudoplusia includens(Walker). Laboratory moths had a greater percentage of whole-body lipids and numbers of chorionated eggs compared with field-collected 3-d-old moths. Females contained a significantly higher percentage of whole-body lipid than males. Late-season (November) females delayed chorionated egg maturation and had higher nonegg lipids than in summer (July, August, and September) and early fall (October) females. Both sexes contained a greater percentage of whole-body lipids late in the fall compared with early-season moths. There was no shift in the daily percentage of mating or number of matings between seasons. Thus, soybean loopers appear to exhibit some of the physiological characteristics associated with Johnson's oögenesis-flight syndrome proposed for migratory insects.