We saw Pharaoh asking for prayers during the second plague. Then in the third plague, when the magicians failed to mimic the Lord's miracle, they confessed saying, -this is the finger of God.---The Lord is using these plagues to show that all power belongs to Him. In the fourth plague the Lord warns Pharaoh before striking. Then He releases a swarm of biting and non-biting flies in the land of Egypt. The miracle in this plague is that, the Lord shields His people from the same flies. Through the flies, the Lord shows a clear distinction between His people, and the Egyptians. The Israelites, even though they are still in slavery, they are experiencing God's-protection. --The Egyptians must have wondered, why are we the only ones attracting flies-