Sand Fly was one of the five open boats usually referred to as barges which, between 1823 and 1825 operated with Commodore David Porter's "Mosquito Fleet" during operations to suppress piracy in the West Indies. These vessels were equipped with sails and between 14 and 20 oars. They were not commissioned and had no regularly appointed commanding officers or crews but were manned from the larger ships of the squadron on an ad hoc basis for each expedition.
When Porter's flotilla departed Norfolk in February 1823, the barges were transported to his base at Thompson's Island (Key West), Fla., in chartered schooners. For over two years, they were quite active against pirates in the Caribbean, especially along the coast of Cuba, but surviving records do not document Sand Fly's specific operations. However, during her service, the United States Navy seriously hampered freebooters in the West Indies.
By the end of 1825, one of the barges had been lost at sea, and others had decayed to uselessness. One or more of these barges, whose names have not survived were still in service at Key West, but details of their subsequent careers are wanting.