The 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: for cll', fl=3'38 x 10-6 ; for oc, fl= 1'96 x 10-6 ; for pe, fl=0'17 x 10-6 , for Sl', fl= 1'10 X 10-6 and for sp, fl=2 '17 x 10-6 . The average was fl= 1'75 x 10-6 or, without pe, fl=2'15 X 10-6 . Estimates for workers were: for by, fl=0'67 x 10-6 ; for cll', fl= 1'45 x 10-6 ; for cll\ fl= l' 39 x 10-6 ; for oc, fl= l' 56 x 10-6; for s", fl=0'25 x 10-6 ; for sp, fl=1'53 x 10-6 . The average for workers was fl=1'14 X 10-6 or, without Sl', f\=1'32 x 10-6. The balanced average somatic mutation rate for drones and workers was fl= 1'6 X 10-6. So far, cr has not shown a single case of reverse mutation, which indicates that either its rate of mutation is less than 2'0 x 10-8 or that it results from a chromosomal deletion. In all cases the mutation rate for a particular gene was greater in males than in workers.