The developmental theory of ageing predicts a positive correlation between developmental time and adult longevity. Experiments that vary larval density and food level have been carried out to test this prediction. The results show differences in viability, developmental time, starvation resistance and adult longevity. It is concluded that pre-adult developmental time is not a causal factor for the determination of adult longevity in Drosophila melanogaster. The observed variation in adult longevity is discussed in relation to viability selection and changed adult physiology.