The penetrance of the female sterile and rough eye phenotypes in cutletrJ865a/Df(2L)ed1 flies is more than 99%. The penetrance of the wing phenotype is 38%. Homozygous eyes contain numerous ommatidial clusters with less than the normal number of photoreceptor cells. The positions of the missing cells suggest that they correspond to presumptive photoreceptors R1, R6 and R7. Homozygous clones grow more slowly than their wild-type twin spots in the eye, wing and leg discs.