A gnat is any of various small dipterous insects or flies, with biting mandibles; term chiefly applied in America to smaller forms, as buffalo gnats, black flies (genus Simulium) or fungus gnats.
Gnat was one of five ship's boats equipped with sails and double banked oars for duty with Captain David Porter's West India Squadron which was fitted out under an act of Congress approved 20 December 1822 to cruise "in the West Indies and Gulf of Mexico for the suppression of piracy." When fully organized the squadron comprised Sea Gull, eight small schooners, Gnat, and five other barges. The squadron was assisted by ships already on the West India Station including John Adams, Peacock, Hornet, Spark, Grampus, and Shark.
On 14 February 1823, ships of the squadron sailed from Hampton Roads to fight it out with buccaneers and rout them in hand-to-hand combat amidst the shallows and mangrove swamps of the Caribbean. Gnat and the other barges were loaded on two chartered schooners and proceeded directly to Porter's base established at Thompson's Island (later named Key West), Fla. From there, the small squadron was used convoying American merchantmen in the Gulf of Mexico, chasing the pirates who dared to venture out, and mounting boat and barge expeditions which scoured the coasts of all the islands to the north of Puerto Rico, including Santo Domingo and Cuba. Every bay and inlet and key of all this region was carefully searched. On 8 April 1823 the pirate schooner Pilot was run ashore near Havana ; two pirates were killed and one captured. In July the expedition encountered the pirate schooner Catilina near Sigaumpa Bay, Cuba. After a running sea fight, pirates jumped overboard while others put off in a launch for shore. Catilina's commander, the notorious pirate Diabolete, was killed in the action. Those pirates not drowned or killed in the sea fight were rounded up ashore and taken prisoners. On 25 March 1825 a pirate's lair was destroyed east of Matanzas, Cuba. Two pirate schooners were captured, at least 8 pirates were killed and 19 were taken prisoner.
Commodore David Porter was succeeded in command by Commodore Lewis Warrington in flagship Constellation. Warrington continued the same system that had been established by Porter, constantly watching the coasts and protecting merchantmen until the freedom of the seas had been assured. In his message of December 1826, the President was able to report to Congress, that piracy had been totally suppressed. From Florida to Cape Horn and even into the Pacific, the Navy had put a stop to outrages by resolute show of force.
The fate of Gnat is unknown. By the close of 1826, it had been reported that one of the five barges had been lost at sea. Some had fallen victim to decay, and the remainder cruised on the Florida Station for the remainder of their careers.