Explanation and summary
The eighth plague of the 10 plagues that the God of the Israelites sent as judgment upon Egypt, through Moses, was a swarm of locusts,. as recorded in the book of Exodus. In this plague, locusts cover the land and eat the remaining vegetation not destroyed by the hail. The Egyptian gods that were insulted by this plague include Isis (the goddess of life), Seth (an eath god), and perhaps others as well. The plague is recorded in Exodus 10:1-20 (see text below).
The plague of locusts was threatened, and so frightened were the servants of Pharaoh that they persuaded him to try to make some agreement with Moses, but the attempt of Pharaoh still to limit in some way the going of Israel thwarted the plan (Exodus 10:7-10). Then devouring swarms of locusts came up over the land from the eastern desert between the Nile and the Red Sea. They devoured every green thing left by the hail. The desperate situation created by the locusts soon brought Pharaoh again to acknowledgment of Yahweh (Exodus 10:16). This was the greatest profession of repentance yet manifested by Pharaoh, but he soon showed that it was deceitful, and again he would not let the people go. When the wind had swept the locusts away, he hardened his heart once more.
Biblical Text (KJV)
1 And the Lord said unto Moses, Go in unto Pharaoh: for I have hardened his heart, and the heart of his servants, that I might shew these my signs before him:
2 And that thou mayest tell in the ears of thy son, and of thy son's son, what things I have wrought in Egypt, and my signs which I have done among them; that ye may know how that I am the Lord.
3 And Moses and Aaron came in unto Pharaoh, and said unto him, Thus saith the Lord God of the Hebrews, How long wilt thou refuse to humble thyself before me? let my people go, that they may serve me.
4 Else, if thou refuse to let my people go, behold, to morrow will I bring the locusts into thy coast:
5 And they shall cover the face of the earth, that one cannot be able to see the earth: and they shall eat the residue of that which is escaped, which remaineth unto you from the hail, and shall eat every tree which groweth for you out of the field:
6 And they shall fill thy houses, and the houses of all thy servants, and the houses of all the Egyptians; which neither thy fathers, nor thy fathers' fathers have seen, since the day that they were upon the earth unto this day. And he turned himself, and went out from Pharaoh.
7 And Pharaoh's servants said unto him, How long shall this man be a snare unto us? let the men go, that they may serve the Lord their God: knowest thou not yet that Egypt is destroyed?
8 And Moses and Aaron were brought again unto Pharaoh: and he said unto them, Go, serve the Lord your God: but who are they that shall go?
9 And Moses said, We will go with our young and with our old, with our sons and with our daughters, with our flocks and with our herds will we go; for we must hold a feast unto the Lord.
10 And he said unto them, Let the Lord be so with you, as I will let you go, and your little ones: look to it; for evil is before you.
11 Not so: go now ye that are men, and serve the Lord; for that ye did desire. And they were driven out from Pharaoh's presence.
12 And the Lord said unto Moses, Stretch out thine hand over the land of Egypt for the locusts, that they may come up upon the land of Egypt, and eat every herb of the land, even all that the hail hath left.
13 And Moses stretched forth his rod over the land of Egypt, and the Lord brought an east wind upon the land all that day, and all that night; and when it was morning, the east wind brought the locusts.
14 And the locust went up over all the land of Egypt, and rested in all the coasts of Egypt: very grievous were they; before them there were no such locusts as they, neither after them shall be such.
15 For they covered the face of the whole earth, so that the land was darkened; and they did eat every herb of the land, and all the fruit of the trees which the hail had left: and there remained not any green thing in the trees, or in the herbs of the field, through all the land of Egypt.
16 Then Pharaoh called for Moses and Aaron in haste; and he said, I have sinned against the Lord your God, and against you.
17 Now therefore forgive, I pray thee, my sin only this once, and intreat the Lord your God, that he may take away from me this death only.
18 And he went out from Pharaoh, and intreated the Lord.
19 And the Lord turned a mighty strong west wind, which took away the locusts, and cast them into the Red sea; there remained not one locust in all the coasts of Egypt.
20 But the Lord hardened Pharaoh's heart, so that he would not let the children of Israel go.
International Standard Bible Encyclopedia, which is in the public domain (with minor edits).