One of the significant features of the 20th century has been a massive increase of insect control by chemicals, an exercise in applied entomology and chemistry; another has been the appearance of insecticide-resistance, a consequence of general biological principles. It is typical of the generosity of Americans, who have played so leading a part in the development of the one and in research on the other, that they have chosen a Canadian to describe them in their Memorial Lecture. This honor is taken as a token of the high regard in which entomology in Canada is now held. It also offers the opportunity of paying tribute to J. H. Comstock, who founded the Department of Entomology at Cornell University which has been Mecca to so many Canadian students.