Larvae of Ephestia of the genotype ml ml were injected on the 8th day after the last larval molt with purified, high molecular DNA from + animals. After the animals hatched, the wings were scored for the occurrence of black pattern scales of type IV. Ten type IV scales were found on 606 wings of treated animals, leading to an estimate of 10-4[long dash]10-5 for aberrant scales. Injection into animals in the process of wing regeneration led to the appearance of clusters of 2[long dash]3 aberrant scales. While it is not yet certain that the aberrant cells constitute transformants, the method appears to be sufficiently specific and sensitive to solve this problem.