Heat induced expression causes a rough eye phenotype and abnormal ommatidia and often lack bristles. Some males are completely or partially sterile. R1-R6 rhabdomeres are small and abnormally shaped. Size of the R1-R6 receptor cells is highly variable, they contain fewer ribosomes, some cells contain many mitochondria and the cytoplasm and nuclei stain less densely. R7 and R8 cells maintain essentially normal morphological features. Many pigment cells are absent or highly abnormal. Mosaic analysis reveals the toxin acts in a cell-autonomous fashion.