16 Then the Lord said to Moses, "Say to Aaron, "Stretch out your staff and strike the dust of the earth, so that it may become gnats throughout the whole land of Egypt.' " 17 And they did so; Aaron stretched out his hand with his staff and struck the dust of the earth, and gnats came on humans and animals alike; all the dust of the earth turned into gnats throughout the whole land of Egypt. 18 The magicians tried to produce gnats by their secret arts, but they could not. There were gnats on both humans and animals.
Matthew Henry's Commentary on Exodus 8:16-18
Commentary on Exodus 8:16-19
(Read Exodus 8:16-19)
These lice were produced out of the dust of the earth; out of any part of the creation God can fetch a scourge, with which to correct those who rebel against him. Even the dust of the earth obeys him. These lice were very troublesome, as well as disgraceful to the Egyptians, whose priests were obliged to take much pains that no vermin ever should be found about them. All the plagues inflicted on the Egyptians, had reference to their national crimes, or were rendered particularly severe by their customs. The magicians attempted to imitate it, but they could not. It forced them to confess, This is the finger of God! The check and restraint put upon us, must needs be from a Divine power. Sooner or later God will force even his enemies to acknowledge his own power. Pharaoh, notwithstanding this, was more and more obstinate.