Objective To explore the effect of L -arginine on pupation time, eclosion time, eclosion rate andmale/ female ratio in Drosophila melanogaster. Methods Two groups of fruit flies were included in this study, the controlgroup received corn meal agar medium (basic medium) and the experimental group received 1% L -arginine added in thebasal medium. Seven pairs of fruit flies were placed in each tube, female: male=1∶1, 12 replicates in each group, and theparent flies were removed after 72 h. The time of pupation, the time of feathering, the number of feathering, and thenumber of males and females in each group were counted. Results After the addition of 1% L -arginine in the basicmedium, the numbers of pupation and feathering, and the feathering rate of the white eye (w¹¹¹⁸ ), residual wing (CyO)and wild type Drosophila melanogaster were increased by 313. 64% and 303. 53% ( P < 0. 01), 157. 09% and 182. 76% ( P < 0. 01), and 233. 33% and 239. 03% ( P < 0. 01), respectively. In the group with addition of 1% L -arginine, thepupation time of the both white eye and wild type flies was 2 days earlier than the control group. Conclusions Addition of1% L -arginine in the basic medium, used under the conditions of this experiment, can increase the fertility of laboratory fruit flies and can be applied to the expansion of laboratory fruit flies.