Exodus 8:17-21

They did so; and Aaron extended his hand with his staff and struck the dust of the earth, and there were gnats on every person and animal. All the dust of the earth turned into gnats through all the land of Egypt.

The soothsayer priests tried with their secret arts to produce gnats, but they could not; so there were gnats on every person and animal.

Then the soothsayer priests said to Pharaoh, “This is the finger of God.” But Pharaoh’s heart was hardened, and he did not listen to them, just as the Lord had said.

Then the Lord said to Moses, “Rise early in the morning and present yourself before Pharaoh, as he comes out to the water; and say to him, ‘This is what the Lord says: “Let My people go, so that they may serve Me.

For if you are not going to let My people go, behold, I will send swarms of flies on you and on your servants and on your people, and into your houses; and the houses of the Egyptians will be full of swarms of flies, and also the ground on which they live.