God give equal opportunity to repent his sins

Exodus 8:16-32
The Plague of gnats: The magicians said to Pharaoh, "This is the finger of God." But Pharaoh's heart was hard and he would not listen. Strike the dust of the ground, the dust will became gnats.
The plague of Flies: But on that day I will deal differently with the land of Goshen, where my people live no swarms of flies will be there so that you will know that I, the Lord, am in this land.
The flies left Pharaoh and his officials and his people; not a fly remained. But this time also Pharaoh hardened his heart and would not let the people go.
This time Aaron did not stretch out his staff.
Why?
Flies speak to us of filth, disease, contamination and they are a nuisance.
A plague of flies meant bad news!
While the common house fly does not bit or sting, some like the Tsetse fly do and all flies are carriers of disease!
In the Scriptures, Satan the devil, that wicked serpent is called Beelzebub. In the Scriptures, Satan the devil, that wicked serpent is called Beelzebub.
Magicians can't produce  gnats by their secret arts, so they confessed that this is the finger of God.
All of these plagues let Egyptians know that the Lord am in this land. So as in the time near the end of day, disaster is more, let people turn to the Lord.
Stretch out the staff means God is with Aaron and Moses, but God can make it with the staff either.
How?
When people hardened his heart even the plagues and disaster happen could not let they turn to the Lord. God give equal opportunity to repent his sins.