A cankerworm is a hungry insect, probably a stage of the locust, and the Bible uses it for ruin that comes in waves. Joel 1:4 lines up the palmerworm, the locust, the cankerworm and the caterpiller, each eating what the last one left. Yet Joel 2:25 carries a promise from God: “I will restore to you the years that the locust hath eaten.” Nahum 3:15-16 borrows the same picture for a proud city that will be consumed. The word is old, but the pattern is plain: loss that seems total, and a God who can give back. Start with Joel 2.
4 verses
That which the palmerworm hath left hath the locust eaten; and that which the locust hath left hath the cankerworm eaten; and that which the cankerworm hath left hath the caterpiller eaten.
And I will restore to you the years that the locust hath eaten, the cankerworm, and the caterpiller, and the palmerworm, my great army which I sent among you.
There shall the fire devour thee; the sword shall cut thee off, it shall eat thee up like the cankerworm: make thyself many as the cankerworm, make thyself many as the locusts.
Thou hast multiplied thy merchants above the stars of heaven: the cankerworm spoileth, and flieth away.
Matthew George Easton, 1897
(Heb. yelek), “the licking locust,” which licks up the grass of the field; probably the locust at a certain stage of its growth, just as it emerges from the caterpillar state (Joel 1:4; 2:25). The word is rendered “caterpillar” in Ps. 105:34; Jer. 51:14, 17 (but R.V. “canker-worm”). “It spoileth and fleeth away” (Nah. 3:16), or as some read the passage, “The cankerworm putteth off [i.e., the envelope of its wings], and fleeth away.”