Charles Ellicott Commentary Jeremiah 51:14

"Jehovah of hosts hath sworn by himself, [saying], Surely I will fill thee with men, as with the canker-worm; and they shall lift up a shout against thee." — Jeremiah 51:14 (ASV)

The Lord of hosts has sworn by himself.— This is, as in Jeremiah 49:13, Amos 6:8, the most solemn form of affirmation. Compare Hebrews 6:13, and Note on Jeremiah 49:13.

Surely I will fill you with men, as with caterpillers. —Better, with grasshoppers or locusts, the fullest type of the swarms of the destroyer (Nahum 3:15). The “Surely” answers to the Hebrew “For if,” as giving the condition on which the shouting depends.

They shall lift up a shout against you. —The thought is the same as in Jeremiah 25:30. The “shout” is that of those who tread the grapes in the wine-press, and that, as in Isaiah 63:2-3, is the received symbol of conquest and destruction.