The Second Affiliated Hospital of Soochow University 1 article published in JoVE Behavior A Simple Technique to Assay Locomotor Activity in Drosophila Xiang Long1, Huanhuan Du1, Mengni Jiang1, Hongrui Meng1,2 1Institute of Neuroscience, Soochow University, 2Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University The present protocol assesses the locomotor activity of Drosophila by tracking and analyzing the movement of flies in a hand-made arena using open-source software Fiji, compatible with plugins to segment pixels of each frame based on high-definition video recording to calculate parameters of speed, distance, etc.