During tests, scientists controlling the RoboBee via a wire tether made it take off, hover, and change direction.
Each wing is attached to the top of an elongated carbon fibre body standing on wire legs. Like those of a real fly, the wings move independently and can rotate as well as flap.
The beating wings create a downdraft that keeps the robot aloft, while forward and backward flight is achieved by tilting its body.
The mini-robot could be developed for environmental monitoring, search-and-rescue operations, or crop pollination. Before that can happen, though, it must be given a miniaturised computer "brain" and a battery pack small and light enough to be carried into the air.
Project leader Professor Robert Wood, from the Harvard School of Engineering and Applied Sciences, said: "It's really only because of this lab's recent breakthroughs in manufacturing, materials, and design that we have even been able to try this. And it just worked spectacularly well."