Alar (Daminozide), a plant growth retardant, is used in different fruit orchards especially of apples and mangoes to increase the production by preventing pre harvest fruit drop, promoting colour development and increasing the storage life. In an earlier study we have demonstrated both neurotoxic and teratogenic effects of Alar in a model organism Drosophila melanogaster. As an extension of the previous work, the present study is designed to investigate the effects of Alar on larval and adult behaviour of the fly. The Results demonstrated no significant alteration in feeding rate of treated larvae, but their foraging path length was shortened considerably, indicating impaired locomotion. Moreover, the onset of their specific courtship behavior like orientation, tapping and wing vibration was significantly delayed which suggest that the treated males were less vigorous and females were less receptive than the controls. In addition, Alar treatment was associated with reduction in copulation duration and subsequent decline in Courtship Index indicating lower reproductive fitness. Collectively, the findings suggest that Alar is ethotoxic for D. melanogaster. © 2019, Zoological Society, Kolkata, India.