Relation of Temperature for Hatching to Elimination of Diapause in Eggs of the Pale Western Cutworm, Agrotis orthogonia Morrison (Lepidoptera: Noctuidae)

Abstract

A weak diapause occurs in eggs of thc pale western cutworm, Axrotis orthogonia Morrison. It does not occur nor is it manifested equally in all eggs. As the eggs are laid in thc fall and hatch the following spring, the diapause 1s sufficient to ensure that they will not hatcll readily upon development to maturity in the fall and that hatchinig is delayed until food is available for the newly hatched larvae (Jacobson, 1962). The rate of hatch of eggs in which diapause has been eliminated varies directly with temperature and hatching may occur at temperatures slightly above freezing (Jacobson and Blakeley, 1958).