The black hole where the locust come from (verse 3) is symbolic of the black hole in our souls according to NT. That place of darkness that only God knows. The place where all our crud lives. The place we don’t’ show anyone. “Humans were made to reflect their wise, loving, creator but somehow their hearts have become full of rebellion, filth and wickedness…. Call it anti-creation…. Call it the black hole inside us all.”
But throughout the vision, according to NT, John wants his readers to know that God and the lamb remain in control; that there is victory in the end. The message is the same in this passage as it is through the whole Bible; those who repent and believe can flush out the crud from the dark hole of the soul and in the end, be spared the wrath of the locust.