Biology and Control of the Purple-backed Cabbage worm in Newfoundland1

Abstract

The purple-backed cabbage worm (Evergestis pallidata Hufnagel) was first reported in Newfoundland in 1943 and is now considered a major pest of cruciferous crops throughout the province. Only one generation was observed. The insect passes the winter in the prepupal stage in an earthen cocoon at or near the surface of the soil. It pupates in June and the moths emerge during the latter part of July. Eggs are laid in masses on the under surface of the lower leaves of susceptible plants, and hatch in 4 to 8 days. There are four larval instars. The species was found to be unusually free from natural enemies, not a single parasite being reared from field-collected larvae in a 3-year study. Satisfactory control was obtained with DDT either as a spray or as a dust. A spray containing 1 lb. of 50% DDT wettable powder in 50 gal. of water applied to cabbage and turnips at 125 gal. per acre gave 90% reduction; 3% dust at 25 to 35 lb. per acre gave 83%.