The pilot said that he had been spraying several corn fields and flying under the power lines. On a pass heading northbound, and flying under power lines, the pilot said that the tail of the airplane caught the bottom wire, tearing the tail off and flipping the airplane on its back. Examination of the accident site revealed an east-west running power line preceding the airplane wreckage by 250 feet. One of the wires showed fraying and unraveling. Examination of the airplane wreckage revealed no anomalies.