Passage
That which the palmer-worm hath left hath the locust eaten; and that which the locust hath left hath the canker-worm eaten; and that which the canker-worm hath left hath the caterpillar eaten.
That which the palmer-worm hath left hath the locust eaten; and that which the locust hath left hath the canker-worm eaten; and that which the canker-worm hath left hath the caterpillar eaten.
Joel 1:2 Hear this, ye old men, and give ear, all ye inhabitants of the land. Hath this been in your days, or in the days of your fathers?
Joel 1:3 Tell ye your children of it, and [let] your children [tell] their children, and their children another generation.
Joel 1:4 That which the palmer-worm hath left hath the locust eaten; and that which the locust hath left hath the canker-worm eaten; and that which the canker-worm hath left hath the caterpillar eaten.
Joel 1:5 Awake, ye drunkards, and weep; and wail, all ye drinkers of wine, because of the sweet wine; for it is cut off from your mouth.
Joel 1:6 For a nation is come up upon my land, strong, and without number; his teeth are the teeth of a lion, and he hath the jaw-teeth of a lioness.
The verse centers on "palmer-worm", "hath", "left", "locust", and "eaten". It is saying that the verse draws attention to "palmer-worm" and "hath", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 3's "Tell ye your children of it and..." into verse 5's "Awake ye drunkards and weep and wail...", so "palmer-worm" and "hath" belong inside that flow. In Joel context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "palmer-worm" and "hath" with trust shaped by these words, not by a vague optimism outside the passage.