White Cutworm:1 Bionomics and Evaluation of Larval Sampling Schemes in Asparagus2

Abstract

The white cutworm, Euxoa scandens (Riley), was studied in commercial asparagus fields between 1973 and 1975. Monitoring adult flight activity with a blacklight trap revealed that male moths were more attracted to the blacklight than females. Males were found to have a unimodal flight activity pattern, whereas females exhibited a bimodal flight activity pattern. In Michigan the white cutworm was found to be univoltine with seven larval instars. Larval food selection was found to be random with equal probability that the larval food would feed on unharvested spears or the “butt” remnants of a harvested spear. Feeding behavior was one of the pnncipal components of plant damage. Four different larval sampling schemes were evaluated: baited and unbaited pitfall traps, baited barrier plots, and baited open plots. Pitfall traps baited with an apple pomace bait formulation of carbaryl caught significantly greater numbers of white cutworm larvae per day than unbaited traps. Baited barrier plots were found to be best for obtaining population density estimates; however, open baited plots were best for larval detection. The number of cutworm larvae trapped was highly dependent on trap orientation to the asparagus rows.