Exodus 8:16-17:

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.
And they did so; for Aaron stretched out his hand with his rod, and smote the dust of the earth, and it became lice throughout all the land of Egypt.

Notes on Exodus 8:16-17:

Lice are a curse!  If you have them, you can command them to be gone, as you do not deserve any curse as a Christian.

See also:

Sickness as Chastening and Judgment in the Old Testament
Condition: Lice