Nahum 3:15
There shall the fire devour thee; the sword shall cut thee off, it shall eat thee up like the cankerworm: make thyself many as the cankerworm, make thyself many as the locusts. There shall the fire devour thee; the sword shall cut thee off, it shall eat thee up like the cankerworm: make thyself many as the cankerworm, make thyself many as the locusts.
Nahum 3:15 belongs to the prophecy of Nahum, which is chiefly concerned with Nineveh, the wicked capital of Assyria. Within that prophecy Nineveh is presented as a type of many later cities.
The verse predicts Nineveh's destruction by fire consuming the city and by the sword cutting off its people, eating them up like the cankerworm. It further declares that multiplying itself many as the cankerworm and many as the locusts would not save Nineveh from that destruction.
That predicted destruction was fulfilled by Assyria's defeat by the combined power of Media, Egypt, and Babylonia, followed by the fall of Nineveh itself.