The pilot said he saw something move inside the cockpit after he had completed a spray run. He glanced down but didn't see anything. He returned his scan to the surroundings and noticed transmission lines level with the aircraft. He pitched the nose up to avoid a collision but encountered a downdraft and was forced into the lines, severing three of them and knocking down a utility pole. The pilot was able to fly the airplane back to the airport and land without incident.