In the story of the fourth plague on Egypt, God threatens to and then does send flies all over Egypt, which contaminates the entire land. In this case, however, the writer makes it clear that the plague does not touch the land of Goshen, which is the dwelling place of the Israelites. So not only does God have the ability to call nature into action on His behalf, but was able to do so with a pinpoint-strike capability. The flies infested Pharaoh’s palace, and avoided the infestation of the land where the childen of Israel dwelled. So He was Lord of the Jews, Lord of the Egyptians, and Lord of the flies as well.
In the next account of the fifth plague, He threatened the cattle and livestock of the Egyptians, and followed through with the destruction of the livestock of the Egyptians, but the livestock of the Israelites was spared. After the flies, Pharaoh agreed to let the Israelites go into the wilderness to offer sacrifices to God, but when the flies relented, he hardened his heart again and changed his mind. The cattle plague was an escalation of sorts, because it was the first time that direct death occured. Although the water turning to blood did affect the fish not being able to live in the river, this time God directly killed the cattle and livestock of Egypt. God is getting more and more extreme in His attacks on Egypt.
What is the moral of the story? When judgement comes upon sinful or disobedient men, God will reserve a blessing for His righteous children. We can see judgement falling all around, but He will protect us and make a distinction between the sinful and the redeemed. We can hide in His hand. We can be covered by His blood and avoid the plagues if we keep our trust in Him and maintain our relationship with the Most High