Operation Big Itch, 1954, was an attempt to discover the potential of weaponized fleas. The operation, part of the Cold War-era United States biological weapons program, took place at Dugway Proving Ground in Utah.
According to "Using the flea as weapon," an article in the Army Chemical Review, "In the United States, the plague flea concept was competing against the use of mosquitoes, flies, ticks, and lice. Of these concepts, the United States put most of its energies behind weaponizing yellow fever in combination with the Aedes aegypti mosquito."