LIFE HISTORIES, FLIGHT PATTERNS, AND RELATIVE ABUNDANCE OF NINE CUTWORMS (LEPIDOPTERA: NOCTUIDAE) IN MANITOBA

Abstract

AbstractSix of the nine most common indigenous species of noctuid moths caught in a light trap at Glenlea, Man., over an 11-year period were univoltine and three were typically bivoltine but sometimes trivoltine. For the univoltine species, the day of peak catch and the day of 50% catch differed only by 3 days or less during 11 years. The timing of flight periods of Feltia jaculifera (Gn.), F. herilis (Grt.), Agrotis venerabilis Wlk., and Nephelodes minians Gn. were not influenced by the degree-days above 10 °C and the standard deviation of the date of 50% catch for these species was within 5–6 days. The date of 50% catch was more variable for Crymodes devastator (Brace) and Euxoa ochrogaster (Gn.), and the variation for the latter was partly explained by a relationship between flight dates and accumulated degree-days above 10 °C. For the multivoltine species, Pseudaletia unipuncta (Haw.), Discestra trifolii (Hufn.), and Xestia adela Franc., the day of peak catch for two generations also varied little from the day of 50% catch for each generation, but the day on which peaks occurred varied from year to year. Only for the first generation of D. trifolii was the day of 50% catch correlated with accumulated degree-days over 10 °C. Moth numbers for each species were not necessarily high when there were reports of crop damage by their respective larvae. There was no correlation between catches of moths in the first and second generation of multivoltine species, and there were no patterns of population trends among any of the economically important species. The life history, feeding habits, and economic importance of each species are discussed.