The general title of this symposium Biological and Chemical Control of Plant and Animal Pests correctly emphasizes the fact that all available means must be used in control of injmious insects. Chemical control usually bas received major emphasis because of the discoveries of new organic insecticides. The virtues and powers of these new insecticides have been publicized by the advertising staffs of the large companies producing them. This is as it should be both because of their great effectiveness and also because, before the mid-1940's, we did not !mow how much damage insects could do. Plants often could not be grown free from insect damage before the discovery of DDT and similar insecticides. Chemical control must continue to be, generally, our first line of defense against mass insect attack.

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