Approximately two-thirds of jumu^Hp126 homozygotes die as pharate adults. The remainder exhibit rough eyes and notched wings. The formation of longitudinal vein 5 is also incomplete in these escapers and bristles on the notum are occasionally lost. These phenotypes are more severe in jumu^Hp126/jumu⁰⁶⁴³⁹ heterozygotes. Sections of mutant eyes reveal an irregular array of ommatidia, and the inner R7 and, to a lesser extent, out photoreceptor cells are missing in a considerable fraction of ommatidia. The spacing of presumptive photoreceptor cell clusters are irregular in mutant eye imaginal discs, with some clusters fused. In this region of the mutant disc, a great increase in dead cells is observed/ F-actin is also found to have accumulated in the cells anterior to the morphogenetic furrow.