The mutation chartreuse-limiio (chli), conferring yellow eye-colour on honeybees, was induced by prolonged gamma radiation of Apis mellifera with 6OCO (Soares, 1975, 1980). In subsequent crosses involving this gene, workers appeared which were unable to use their stings, these being structurally abnormal. The new phenotype was called split-sting (sps). The character had a frequency of 3·5% in the population when first observed, but this was raised to 62·0% after a selection programme. New crosses are under way to try to increase the frequency of this character still further.