TEMPORAL OCCURRENCE OF THE VARIEGATED CUTWORM (LEPIDOPTERA, NOCTUIDAE) ADULTS IN IOWA WITH EVIDENCE FOR MIGRATION

Adult activity and ovarian dynamics of the variegated cutworm, Peridroma saucia (Hübner), were studied during 3 yr by using blacklight traps. Initial mating in females coincided with ovarian development, with females continuing to mate up to six times during their lives. Adult catches, ovarian dynamics, and degree-day calculations indicated that P. Saucia has three generations each year in Iowa. Very few preovipositional females were collected during the spring flight. This observation and the strong association of adult activity during the spring with weather patterns resulting in southerly winds suggested that P. Saucia adults migrate into the state each spring when weather conditions are favorable. Flights during June through November contained a large portion of preovipositional females. Degreeday calculations also revealed that adults collected during June and July were the progeny of spring migrants, but temporally distinct influxes of migrants may produce distinct peaks of adult activity during June and July. Degree-day calculations and the collection of a few preovipositional females during the spring suggested that P. Saucia may overwinter as pupae, which may produce adults that contribute to the influx of migrants in the spring. © 1990 Entomological Society of America.