Ultraviolet A (UVA) radiation (400–315 nm) is the major component of solar ultraviolet (UV) radiation that reaches the Earth's surface due to the role of the stratospheric ozone. UVA radiation can induce various types of negative effects in all organisms including insects, such as oxidative stress, cell death, and photo-receptor damage. The objective of this study was to further elucidate the biological effects of UVA radiation on diurnal insects. In the present study, the effects of UVA radiation on adult longevity and fecundity in a model diurnal insect, Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae), irradiated at different UVA-exposure times and intensities were investigated, as well as the developmental duration and cumulative survival rate of the first filial generation. The longevity of adults exposed to relatively low-intensity UVA radiation was prolonged for both sexes, and there was a significant increase observed after exposure for 3 h/day. The results also showed that UVA radiation did not induce mortality under our experimental conditions. Fecundity increased slightly with increasing UVA-exposure times but not significantly. Exposure to UVA radiation significantly prolonged the developmental duration from egg to emergence of the first filial generation. The cumulative survival rate from egg to emergence of the first filial generation was significantly elevated, but only when the parents were exposed to relatively low-intensity UVA radiation for 2 h/day. These results will aid in understanding the biological effects of UVA radiation on diurnal insects and give new insights into the mechanisms of adaptation/resistance to environmental factors in insects.