“What the cutting locust left,
The swarming locust
Has eaten.
What the swarming locust left,
The hopping locust
Has eaten.
What the hopping locust left,
The destroying locust
Has eaten.”
The big event that Joel was talking about was a locust plague. Apparently, there were a series of locust attacks, a fairly common event in the ancient world. The mild-mannered grasshoppers would suddenly join in groups during times of drought and then attack the growing grain fields in droves. There must have been three separate attacks. Joel called them cutting locusts, swarming locusts, and hopping locusts. One came right after the other to destroy the field crops.
Eugene Finnegan Bible Project 