Feeding expts. have indicated that diet deficiency affects the general vitality of insects and the prolificacy of the [female][female]. Tests made by the author indicate that elemental deficiency or variation may likewise materially affect the prolificacy of [female][female]. The so-called trace elements were given particular attention. Tests indicate the possibility of a long-range effect of elemental absorption upon insect populations. This absorption may be directly through the leaf surface or by way of the root system. Indications are in many cases insect populations increase following fungicidal applications may be due more to a physiological change in cell sap than to a destruction of beneficial fungi.