On May 14, 2000, at about 1215 eastern daylight time, a Piper PA-22-150, N6860B, registered to a private owner, operating as a 14 CFR Part 91 personal flight, experienced a loss of engine power in the vicinity of Highlands, North Carolina. The pilot made a forced landing into the trees. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The private pilot and one passenger reported no injuries. The flight originated from a private airport in Highlands, North Carolina, about 15 minutes before the accident. The pilot stated he departed from the private airport to the south, climbed to 3,100 feet and started to level off when the airplane engine started running rough. He increased the mixture; the engine rpm increased and the engine ran smooth, then the engine started running rough again. He made a right turn while descending and the engine quit. There were no suitable landing areas available, and a forced landing was made to the trees. The pilot stated in a subsequent statement, "There is a good possibility (and I am 99% sure) I was on the left tank, because I always made a practice of using the left tank when the right tank was half or less, because the right tank was placarded for level flight only 1/3 or less." Examination of the airframe and flight control assembly revealed no evidence of a precrash mechanical failure or malfunction. Continuity of the flight control system was confirmed for pitch roll and yaw. Examination of the left and right fuel tanks revealed the fuel cap vents, and forward and aft fuel supply lines at the fuel tank were unobstructed. The forward and aft fuel supply line on the right side of the fuselage was unobstructed. The forward fuel supply line on the left side of the fuselage was not obstructed. The aft fuel supply line on the left side of the fuselage was obstructed. The line was removed and was found to be obstructed by insect larva from an undetermined source. Review of the aircraft logbooks revealed the wings were removed and recovered on July 24, 1980. No other maintenance was recorded as being performed on the wings. The engine assembly was removed from the airplane and mounted on a test stand. The engine started, ran, and developed power