The book of Joel mentions four types of locusts that would destroy the agriculture of Israel. Joel 1:4 says, “What the cutting locust left, the swarming locust has eaten. What the swarming locust left, the hopping locust has eaten, and what the hopping locust left, the destroying locust has eaten” (ESV). When were these predictions fulfilled? Were these literal locusts or a metaphorical reference to something else?
The time of the fulfillment depends, to some extent, on the date the book of Joel was originally written. Scholars debate the exact time of composition, but it was likely around 845 B.C.
In chapter 1, Joel describes the devastation caused by an invasion of locusts. The damage is so severe that the nation is brought to ruin; every strata of society is affected: drunkards (Joel 1:5-7), citizens of Jerusalem (Joel 1:8-10), farmers (Joel 1:11-12), and priests (Joel 1:13). The prophet then calls on the people of God to repent.
Some interpreters see the locusts as symbolic of an invading army, suggesting the locusts refer to another animal such as a horse (similar to Jeremiah 51:27). Other commentators view these locusts as a reference to modern-day helicopters, interpreting Joel’s prophecy as a prediction of a future war. However, such views neglect the intention of the author and the understanding of the original audience. Israelites saw locust swarms as deadly due to the locusts’ ability to wipe out an entire year’s harvest. Locust plagues had been seen before (Exodus 10:1-3; Psalm 105:34-35).
There is no doubt that Joel was warning his readers about a future day when God would judge all people. Most likely, Joel used a recent devastation of locusts as an illustration of Judgment Day. The disaster brought upon Israel’s agriculture was a small taste of a coming judgment on Israel and a later judgment upon the whole earth. Part of this prophecy was fulfilled when Israel was defeated by its enemies and taken into exile. The remaining judgments (2:28ff) will take place in the future Day of the Lord.
In summary, the prophet Joel is most likely referring to a literal locust invasion that took place shortly before his writing, around 845 B.C. The literal swarms of locusts that invaded in successive waves to destroy the crops of Israel spoke of a soon-coming invasion of enemies as well as a future day of judgment.