en_tn/nam/03/17.md

your commanders are like locusts that camp in the walls on a cold day. But when the sun rises they flee

Nahum compares the way that the officials in Nineveh will flee when the battle starts with the way that locusts will remain still while it is cold, but will fly away when the sun rises and the air becomes warm. (See: rc://en/ta/man/jit/figs-simile)

the place they go to is not known

"and no one knows where they have gone"