Under a common laboratory environment, three isofemale lines of Aedes (Stegomyia) aegypti were used to score metric properties (size and shape) of the wings during 10 generations. Since the number of generations was much higher than the number of founders in each line, genetic drift was expected to occur. Size tended to slightly increase with time, but its variation among the successive generations did not show any detectable information specific to each line. Shape could discriminate among lines in females. Males of lines A and B were not discriminated before generation 8, after which they became completely separated. For each line at each generation, the variance of size and the metric disparity index (as an estimate of shape variance) were higher in females than in males. From one generation to another, the within line shape variance decreased in both sexes, while shape similarity progressively and consistently decreased between males of lines A and B. At each generation, in both sexes, shape variance of the pooled lines was higher than that of each line separately, a pattern not observed for size variance. In conclusion, shape, as a metric property, was closer to a genetic character than size: (i) it showed modifications compatible with the hypothesis of genetic drift and (ii) its variation was related to the complexity of the sample.