Some scholars understand this section as a second description of the locust plague in chapter 1. But in chapter 1, the plague is described as a past event. In this section, the verb tenses seem to describe a future event.
For this reason, other scholars understand the passage as a warning of another locust plague that has not yet happened.
Still other commentators understand this passage as apocalyptic language (symbolic language about God’s future judgment). In this view, the writer uses the imagery of a locust plague to describe an invading human army on the coming day of the Lord.