Exodus 8:17-19

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. Then the magicians said to Pharaoh, “This is the [supernatural] finger of God.” But Pharaoh’s heart was hardened and he would not listen to them, just as the LORD had said.