John Calvin on Nahum 3:17

And thy princes are as locusts: this refers to the wicked doings, by which they laid waste almost the whole earth. As then the locusts and chafers, wherever they come, consume every kind of food, devour all the fields, leave nothing, and the whole land becomes a waste; so also have been thy princes; they have been as locusts and thy leaders as the locusts of locusts, that is, as very great locusts; for this form, we know, expresses the superlative degree in Hebrew. Their leaders were then like the most voracious locusts for the whole land was made barren by them, as nothing was capable of satisfying their avarice and voracity.

The Prophet then adds, They are locusts, who dwell in the mounds during the time of cold; but when the sun rises, not known any more is their place He now shows, that it would not be perpetual, that the Ninevites would thus devour the whole earth, and that all countries would be exposed to their voracity; for as the locusts, he says, hide themselves in caverns, and afterwards fly away, so it shall happen to thy princes. But this passage may be taken to mean, — that the Ninevites concealed themselves in their hiding-places during the winter, and that when the suitable time for plundering came, they retook themselves in different directions, and took possession of various regions, and brought home plunder from the remotest parts. This meaning may be elicited from the words of the Prophet; and the different clauses would thus fitly coalesce together, that when the Ninevites left their nests, they dispersed and migrated in all directions. I do not at the same time disapprove of the former meaning: they are then like locusts, who lodge in mounds during the time of cold; but when the sun rises, — that is, when the season invites them, (for he speaks not of the winter sun,) but when the heat of the sun prevails and temperate the air, — then, he says, the locusts go forth and fly away, and known no more is their place He means, in short, that the Ninevites plundered, and that they did so after the manner of locusts; and that a similar end also was nigh them; for the Lord would destroy them, yea, suddenly consume them, so that no trace of them could be found. It follows —

Nahum 3:18

18. Thy shepherds slumber, O king of Assyria: thy nobles shall dwell in the dust: thy people is scattered upon the mountains, and no man gathereth them

18. Dormitaverunt pastores tui, rex Assur; jacuerunt fortes tui; dispersus est populus tuus super montes, et nemo congregans.