SummaryThe average numbers of ommatidia in the eyes of workers was 3826 and in the eyes of males 7082. Somatic mutations from recessive to dominant were detected in 7 genes, some reported in this paper, some in an earlier publication. The rates of reverse mutation estimated for males were: forchrr,μ=3·38×10−6; foroc,μ=1·96×10−6; forpe,μ=0·17×10−6, fors−la,μ=1·10×10−6and forsp, mu=2·17×10−6. The average wasμ= 1·75×10−6or, withoutpe,μ=2·15×10−6. Estimates for workers were: forby,μ=0·67×10−6; forchr,μ=1·45×10−6; forchli,μ=1·39×10−6; foroc,μ=1·56×10−6; forsla,μ=0·25×10−6; forsp,μ=1·53×10−6. The average for workers wasμ=1·14×10−6or, withoutsla,μ= 1·32×10−6. The balanced average somatic mutation rate for drones and workers wasμ= 1·6×10−6. So far,crhas not shown a single case of reverse mutation, which indicates that either its rate of mutation is less than 2·0×10−8or that it results from a chromosomal deletion. In all cases the mutation rate for a particular gene was greater in males than in workers.