The question of the effect of poisons on the blood of insects is a new one in entomo-toxicological literature. In a series of works by Metalnikov (1908, 1924, 1927) we have a study of the reaction of the blood of the larva of the Wax Moth (Galleria mellonella) in consequence of an injection into the body cavity of various substances and morbiferous microbes. The paper by Mrs. Tareeva and Nenyukov (1931) describes, very briefly and in general features, the picture of the blood of Calliptamus italicus in the case of poisoning by means of sodium arsenate or sodium fluoride.