Exodus 8:21-24

For if you do not let My people go, hear this: I will send swarms of [bloodsucking] insects 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 insects, as well as the ground on which they stand. But on that day I will separate and set apart the land of Goshen, where My people are living, so that no swarms of insects will be there, so that you may know [without any doubt] and acknowledge that I, the LORD, am in the midst of the earth. I will put a division (distinction) between My people and your people. By tomorrow this sign shall be in evidence.” ’ ” Then the LORD did so. And there came heavy and oppressive swarms of [bloodsucking] insects into the house of Pharaoh and his servants’ houses; in all the land of Egypt the land was corrupted and ruined because of the [great invasion of] insects.