Microinsect Flight: Recent Advances and Broad Prospects for a Comprehensive Study

The smallest insects are particularly useful for studying how body size affects flight mechanics, because they include the smallest flying animals and operate at single-digit Reynolds numbers, where viscous forces play a much greater role than in larger insects and other flying animals. This area has attracted researchers for several decades, but until recently all work on "miniature" insects focused on species that are many times larger than the smallest insects. Recent work on some of the smallest insects has revealed the uniqueness of both the structure of their wing apparatus and the kinematics and aerodynamics of their flight. This review summarizes recent advances in the study of miniature insect flight and identifies unresolved questions that will shape future research in biology, biomechanics, and bioinspired technologies, providing broad prospects for a comprehensive study of this subject.