A study was made of the spatial pattern of the progeny produced in boxes with 25 oviposition tubes, by groups of six Drosophila melanogaster females during 24, 72 and 216 h. Each female was fertilized by a male carrier of a dominant mutation in such a manner that the behavior of each female of the group as well as that of each group could be determined by a study of their progeny. The pattern of spatial distribution of the progeny was aggregated, reaching its highest value at 72 h. Gregarious behavior of individuals was defined by the number of sites among which they disseminated their progeny in a 24 h-cycle; while for groups it was estimated by the variance/mean ratio. The fertility, egg-adult development time and mortality rate were recorded. Comparisons between the tubes showed statistically significant differences in the number of individuals and of phenotypical composition. These gregarious distributions could contribute to local genetic differentiation.
