Egypt's plague of lice and flies

Exodus Chapter 8: 15 But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.
16 And the LORD said unto Moses, Say unto Aaron, Stretch out thy rod, and smite the dust of the land, that it may become lice throughout all the land of Egypt.
17 And they did so; for Aaron stretched out his hand with his rod, and smote the dust of the earth, and it became lice in man, and in beast; all the dust of the land became lice throughout all the land of Egypt.
18 And the magicians did so with their enchantments to bring forth lice, but they could not: so there were lice upon man, and upon beast.

Exodus Chapter 8: 22 And I will sever in that day the land of Goshen, in which my people dwell, that no swarms [of flies] shall be there; to the end thou mayest know that I [am] the LORD in the midst of the earth.
23 And I will put a division between my people and thy people: to morrow shall this sign be.
24 And the LORD did so; and there came a grievous swarm [of flies] into the house of Pharaoh, and [into] his servants' houses, and into all the land of Egypt: the land was corrupted by reason of the swarm [of flies].