Dispersal, Flight, and Diurnal Activity Patterns of Adult Southern Corn Billbugs (Coleoptera: Curculionidae)

Dispersal into cornfields, flight, and diurnal activity patterns of the adult southern com billbug (SCB), Sphenophorus callosus (Olivier), were studied in eastern North Carolina during 1979 and 1980. Com plant damage (an index of SCB density) in fields with different cropping histories was initially concentrated either on the field edge next to last year\u27s corn in rotated fields, or the edge next to the overwintering site in nonrotated fields. Although damage patterns and trapping studies suggested that SCB dispersal into fields was primarily by walking, SCB are capable of strong flight. Weevils of both the overwintered and summer generations were caught in flight traps. Diurnal activity patterns of adult SCB were often bimodal; peak numbers of adults were found on plants and caught in pitfall traps in late morning and mid- to late afternoon. Changes in adult activity appeared to be better explained by changes in temperature than by changes in light intensity. Least activity occurred when temperatures were above 30°C or below 20°C