A genetic analysis of two laboratory strains of Drosophila melanogaster that displayed opposite oviposition tendencies with respect to egg, insertion behavior was performed. In general, the insertion characteristic appears to be dominant over the noninsertion characteristic and is controlled by a polygenic system associated mostly with chromosomes 2 and 3. The results of this study indicate that these genes may be concentrated at the distal end of chromosome 2L and at the distal end of chromosome 3R, and their presence on both of these chromosome regions is needed to approach the full egg insertion effect, suggesting the presence of interaction among genes in these two regions.