The Locust Swarm in the Book of Joel

In chapter one, we get a description of an actual literal locust swarm that came and crashed onto presumably Jerusalem and Judah in a literal sense. And so the second locust swarm happens in chapter two and it looks more like a figurative locust swarm. Joel just generically is like, hey, we got to repent. What of? I don't know. He quotes like eight other books of the Old Testament. Presumably everybody reading the book kind of knew what they were getting wrong and what to repent of.