Flies from a wild type strain of Drosophila melanogaster, previously kept at 25 degrees C, were reared at either 20, 25 or 29 degrees C. As expected, developmental time and adult body size decreased with increasing temperature. Adult longevity of flies reared at 25 degrees C was slightly greater than that of flies raised at 20 or 29 degrees C when measured at all three temperatures. This may reflect the laboratory history of the strain. On the whole, it appeared that longevity was independent of adult body size. These results support our previous conclusion (Zwaan et al., 1991) that developmental time and body size are not causally related to longevity in 'environmental' studies. It is stressed, that genetic analysis is needed to investigate the reputed correlation between development and ageing.