This paper reports a MEMS micro force sensor with differential tri-plate comb drives. Bulk micromachining is utilized to construct the high aspect ratio devices. The sensor has a high sensitivity, good linearity, and a large bandwidth, which are required for characterizing flight behavior of fruit flies (Drosophila). The technique allows instantaneous flight forces, which result from the combination of aerodynamic forces and inertial forces, to be captured in real time, providing valuable data for understanding flight biomechanics in Drosophila. The integration of the MEMS micro force sensors into flight simulators will provide a novel and efficient experimental paradigm for further insect neurophysiology studies. The potential impact of this research extends beyond gathering flight data on Drosophila by demonstrating how MEMS technology can be used to provide valuable tools for biological investigations.