The pilot reported that he was performing an aerial application pass when he felt a “big tug” on the helicopter. The pilot realized he had struck a wire as the helicopter pitched up and started to slow. The helicopter flew about 150 yards when the pilot felt another “huge jerk” on the rear of the helicopter. The helicopter started to spin and rotated about 2-3 times before it impacted the ground and rolled over coming to rest on its left side. On exiting the helicopter, the pilot observed the wire wrapped around the helicopter. It had cut into the tail rotor gearbox “tearing it” off the helicopter. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operations. The pilot reported that prior to conducting the aerial application pass, he circled the field and did not observe any obstructions. The pilot did not submit the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report Form 6120.1.