Vegetable leaf miner (Liriomyza sativa) being a dipteran fly possesses polyphagous feeding nature. Among the insect pests attacking yard long bean, vegetable leaf miner once considered as a secondary pest is now appearing as a primary pest due to disruption of associated natural enemies. With a view to study the biology, investigation was carried out in entomology laboratory, Department of Entomology, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka during January to April, 2021. Results revealed that at laboratory condition, incubation period was 2.12 ± 0.31 days, larval stage lasted for 4.57 ± 0.49 days and pupal stage remained for 7.85 ± 0.67 days. Irrespective of sex, adult leaf miner lived for 1.5 ± 0.46 days without food source whereas 4.9 ± 2.20 days with supplementary food source. Higher pupal mortality (54.08%) was observed than larval mortality (21.07%).