In this paper we present the concept, fabrication, and testing of resonant cantilever wings for monolithic micro aerial vehicles (MAVs). Combining new analytical and computational fluid dynamic work to determine the resonant mode, forces, and power of resonating curved cantilevers, we present a framework to calculate and optimize robot designs for certain figures of merit (i.e., greatest excess power, smallest size, and fastest time for a swarm to search a volume). The optimization results reveal promising designs on scales ranging from fruit flies to dragonflies with the optimal MAV having a maximum continuous travel speed of 2 m/s, 10 mm wing length, and 9 mg total mass. We then fabricate curved cantilever wings to test the theoretical model, which confirm the resonant frequency, resonant mode shape, power dissipated, and net force generated. This work is the first demonstration of asymmetric force from a symmetric flapping cycle and of the feasibility of curved cantilever wings for completely monolithic MAVs.