During an application flight, the pilot maneuvered the helicopter in order to conduct another pass, maintaining vigilance of the high lines and trees in the vicinity of his operations. The pilot stated that he did not see the 2 wires spanning from across the road into the bean field where he was applying insecticide. He flew right into the wires which subsequently entangled around the mast of the helicopter. During the forced landing to the field, the "controls locked up" and the helicopter spun to the right 3 times before impacting the ground. The helicopter was substantially damaged. The pilot reported no preimpact mechanical failures or malfunctions with the helicopter that would have precluded normal operation.