Abstract
During the study of the biology of two hymenopterous parasites which were being bred with a view to their utilization as biological control agents, certain interesting facts were observed with regard to the occurrence of diapause. It was found that the age of the parent female when an egg was laid had some influence on the tendencies of the larval progeny to enter diapause. This effect has already been briefly described (Simmonds 1946). Further, it was found that variations in the diet and temperature of development of the parent female had marked effects on her progeny in the same respect. Observations on the occurrence of diapause in many different species are legion, and it is not intended to enumerate these or to discuss in detail the manner in which each example may possibly be correlated with the experimental data obtained here. Various aspects of diapause and numerous examples occurring in the literature have been discussed by Cousin (1932) and Wigglesworth (1939), and examples occurring in the parasitic Hymenoptera by Flanders (1944).