Muscles provide the force necessary to generate movements that drive locomotor behaviors. Flying Drosophila use only a dozen pairs of flight steering muscles to regulate wing motion during both quick maneuvers and slow compensatory reflexes. Prior work demonstrated that the steering motor system is functionally stratified; small tonic muscles provide continuous, fine-scaled adjustments in wing motion while large phasic muscles execute rapidmaneuvers. My research aims to identify the mechanisms by which networks of local and descending interneurons control these two systems to generate a continuous stream of cohesive motor commands during flight. To identify cells that underlie flight behavior we use optogenetic techniques to perturb the activity of identified neurons and usequantitative behavioral techniques to measure changes in wing motion. To understand precisely how neural activitydrives changes in behavior, I will simultaneously measure wing kinematics and activity across the entire array of flight control muscles during optogenetic perturbation of functionally relevant interneurons. By integrating technological advances in neurogenetics and brain connectomics, I aim to understand the flow of information to the motor system at single-cell and circuit-level resolution. This work will provide a comprehensive view of the flight motor control system, detailing features from the level of animal behavior to the genetic identity of the circuit components controlling them.