The Lord said to Moses, "Tell Aaron to strike the ground with his stick, and all over the land of Egypt the dust will change into gnats."
So Aaron struck the ground with his stick, and all the dust in Egypt was turned into gnats, which covered the people and the animals.
The magicians tried to use their magic to make gnats appear, but they failed. There were gnats everywhere,
and the magicians said to the king, "God has done this!" But the king was stubborn and, just as the Lord had said, the king would not listen to Moses and Aaron. 1
References for Exodus 8:19