Exodus 8:17-18

They did so; Aaron stretched out his hand with his staff and struck the dust of the earth, and there were [biting] gnats on man and animal. All the dust of the land became gnats through all the land of Egypt. The magicians (soothsayer-priests) tried by their secret arts and enchantments to create gnats, but they could not; and there were gnats on man and animal.