“…Previous studies of the karyotypes in this family (Metz, 1916;Boyes, 1953Boyes, , 1963Kaul et al, 1978) have shown that the size of the sex chromosomes varies considerably among species, as also occurs for other dipteran groups (Boyes and Boyes, 1975;Kaul and Tewari, 1979; Parise, P.P.M., unpublished data). The results of our analysis of the karyotype of P. intermutans fit this pattern of autosomal and sex chromosomic organization.…”