PHENOLOGY AND REPRODUCTIVE STATUS OF ADULT REDBACKED CUTWORMS, EUXOA OCHROGASTER (GUENÉE) (LEPIDOPTERA: NOCTUIDAE), IN SOUTHERN MANITOBA

Abstract

AbstractThe phenology and reproductive status of adults of the redbacked cutworm, Euxoa ochrogaster (Guenée), were determined from blacklight (BLT) and sex-attractant (SAT) trap catches at four locations in southern Manitoba in 1987 through 1989. The flight period was of 9–12 weeks duration, extending from late June to early October. The first male and female moths were captured at about the same time in the BLT and SAT. The peak catches of the BLT occurred during the first 3 weeks of August (weeks 5 and 6 of the flight period) and those of the SAT about 1 week later. The SAT continued to capture male moths for 2–3 weeks after the last moths appeared in the BLT. Most females captured during the first 2–3 weeks of the flight period were virgins who had not yet initiated egg development. Most mating, egg development, and oviposition took place during a 3- to 4-week period that included the 2 weeks before, the same week as, and the week after the peak BLT catches (weeks 3–7 of the flight period); these activities occurred in the 3–4 weeks before the peak SAT catches. The data suggested that there was competition between SAT and females in attracting males and, consequently, the SAT catch data may not be providing accurate measurements of the sizes of breeding populations of males in the field. The BLT catches underestimated the length of the flight period by about 1.5–3 weeks.