This they did, and when Aaron stretched out his hand with his staff and struck the dust of the earth, gnats came upon man and beast. All the dust of the earth turned into gnats throughout the land of Egypt.
The dust itself obeys God's command; He has infinite arrows in His quiver. When the magicians failed here, they had to confess "This is the finger of God", a divine power that has the devil on a chain, and stops him short with nothing but a gesture.
AI summary
Commenting on Exodus 8:16-19
And the magicians did so with their enchantments, to bring forth lice,.... They made use of their magical art, and juggling tricks they were masters of, to produce the like sort of creatures, or at least to make such appear, or seem to appear, to the eyes of men: but they could not; God would not suffer them to do it, to impose upon Pharaoh...
The very smallness of these insects made them a terrible scourge in Eastern lands, where their sting embitters life; their insignificance became their terror. The magicians never even tried to imitate them, and owned at last, This is the finger of God.
AI summary
Commenting on Exodus 8:16-19