Shoo Fly Pie may be a variation of the older Treacle Tart. Treacle is the British generic name for any syrup made during the refining of sugar can; i.e. Treacle, Black Treacle, Molasses, Golden Syrup, and Blackstrap are all treacles. During the 17th century, treacle was used chiefly as a cheap form of sweetener. By the 1700’s, refined sugar became affordable to the masses in Britain and overtook treacle as a general sweetener. Molasses was often substituted for treacle in colonial American recipes. Many early cookbooks have Molasses Pie recipes.