Wings are the defining character of pterygotes, and were a key innovation in the evolutionary history of insects. Flight is important for a vast range of activities, and the detailed structure and form of the wings primarily reflects their adaptation for flight. The wings are connected to the thorax via the most complex joints of any animal, and the thoracic musculature provides control of the wings as well as high power output. By varying their detailed wingbeat kinematics, many insects are able to achieve excellent agility and maneuverability. The aerodynamics of insects differ greatly from the aerodynamics of fixed-wing aircraft, and it is these differences that explain the ability of insects to lift their weight with comparatively small wings. Even so, flight is the most energetically demanding of an insect's activities, and the power for flight may be provided by oxidation of several different substrates. Flight is only useful if it is stable and controlled, and a range of different sensory systems is used to provide the necessary feedback.
This chapter is divided into seven sections. Sections 9.1 and 9.2 describe the structure and form of the wings. Section 9.3 considers how the movements of the wings are generated, and is followed by Section 9.4 on wing kinematics. Section 9.5 reviews the aerodynamic mechanisms of insect flight, and is followed by Section 9.6 on power. Section 9.7 describes the sensory systems that are used by different insects in flight control.