The governing relations are formulated and solved describing the extraction of energy through piezoelectric (PZT) devices in elastic and viscoelastic wings, a process generally referred to as energy harvesting or scavenging. The process can be used not only to store the recovered energy but also as a control device to prevent torsional divergence, fluter, control reversal, material failures, creep buckling, excessive deflections, etc. This can be accomplished by means of combinations of optimal designer viscoelastic, aerodynamic and PZT or magnetic properties. However, the requirements are diametrically opposed as harvesting calls for large deflections and hence more power generation, while stability demands small and limited deflections. Illustrative examples are presented and evaluated. The evolution to and beyond optimum states of several principal parameters is studied and illustrated.