Regarding the conundrum of the four stages of locusts in Joel 1, Nogalski says:
“Rather than searching the past, a command is given to recount ‘it’ to
future generations, making sure the message is conveyed for four generations…
Significantly, then, this dual command refers to the message the prophet wants
to convey, not to an event…the number of locusts corresponds to the number of
generations who are to be told of ‘it' in 1:3.”
Therefore, according to Nogalski, the locusts should not be investigated as one historical plague that had a four-stage program of destruction that Joel reports. Rather, the locusts are figurative (as the Rabbis and early church fathers also read them). They represent the four generations who have been told "[Has anything like this ever happened in your days or in the days of your ancestors?] Tell it to your children, and let your children tell it to their children, and their children to the next generation." (Joel 1:2-3)
Interestingly, the LXX has a different order of the first six of the Minor Prophets than does the MT (English Bible also); where Joel is second. In the LXX Joel is fourth. According to the LXX reader/theologian/redactor/editor, is Joel the fourth generation? Amos and Micah make plenty of sense as precursor-generations to Joel.