Studies on the Thermal Constants and Seasonal Occurrence of the Seed-Corn Maggot in Wisconsin1

Abstract

The thermal constants for various stages of development of the seed-corn maggot, Hylernya cilicrura (Rond.), were investigated. After determining the threshold of development at approximately 50º F., observations on eight insectary cultures yielded the following thermal constants: egg development, 46 day-degrees; larval and pupal development, 236 and 287 day-degrees, respectively. Nineteen insectary cultures indicated 572.5 day-degrees from egg to adult. Field data indicated 600.7 day-degrees from adult to adult. The theoretical number of generations during 1957 in Wisconsin was 5.26. Four complete generations and two partial generations were observed in the field. Under field conditions, the preoviposition period was 2 to 3 days. The probability of seed-corn maggot estivation during the hotter summer months was low.