The seasonal history of an insect has an important relationship to the success or failure of any efforts to usr parasites in its control. In the work on parasites of thr European corn borer, Pyrausta nubilalis Hubn., over a period of years, the writer has had an opportunity to observe the changes which have taken place in the seasonal history of this insect in Western Ontario. It was shown by the writer (Wislwt, 1942, 1944) that there was a gradual and rather consistent increase in the proportion of the population which had two generations instead of one. The present paper presents further data pertinent to this subject.

This project arose out of studies of the European spruce sawfly, Gilpinia hercyniae (Htg.), in connection with the Canadian Forest Insect Survey at the Dominion Entomological Laboratories, Fredericton, N.B. Bessa selecta (Mg.) had been observed as a parasite of the larch sawfly, Pristiphora erichsoni (Htg.), but particular interest was aroused in it as a parasite occurring on the European spruce sawfly. The latter host was frequently found to bear the eggs and integumental funnels of B. selecta. The object was to study its biology and effectivness as a possible control factor of the spruce sawfly. However, great difficulty was experienced in rearing the host due to high mortality caused by disease. Hence the original aims were not attained to the entire satisfaction of the author.