a crop-destroying locust, named for the way it shears vegetation off
The name is a verdict, not a species label. Hebrew built this insect's name from a verb meaning "to cut off, prune, shear," so the word says roughly "the shearer." It identifies the creature by what it does to a vineyard rather than by how it looks, exactly the way another locust name in the same list means something like "the finisher" (חָסִיל).
All three appearances are scenes of ruin. In Joel 1:4 the shearer heads a chain of four locust names, each wave eating whatever the wave before it left. In Joel 2:25 the same four names return in a different order, with the shearer now last, as God promises to repay the years the swarm ate. In Amos 4:9 it stands alone: God struck the gardens, the vineyards, the fig trees and the olive trees, and the shearer devoured them.
That reshuffled order in Joel is why most scholars today no longer read the four names as four species, or as four stages in one insect's growth. A prophet describing a life cycle would not put the stages in a different order the second time around. The four names are better heard as four ways of naming a single catastrophe, each accusing the insect from a different angle: this one shears, one swarms in sheer numbers (אַרְבֶּה), one licks the ground bare (יֶלֶק), one finishes off whatever is left.
Amos settles the point that the shearer needs no chain of companions to make sense. Used by itself, with no sequence in view and mature olive trees as its victims, the word carries the whole weight of "the destroyer" on its own.
Disputed
Whether gazam denotes a specific insect or stage, or is simply a general name for the destructive locust.
- majorityA general term for a destructive locust, with no species or developmental stage specified; the name describes the damage, not the taxon.; BDB, s.v. גָּזָם, p. 160; HALOT, s.v. גָּזָם; Duane A. Garrett, Hosea, Joel (New American Commentary 19A; Broadman and Holman, 1997), 316
- minoritySpecifically an early, wingless, crawling stage of the desert locust, the reading preserved in the Aramaic tradition (Targum Jonathan and the Peshitta both render zaḥlā, a legless locust).; Wilhelm Gesenius, Thesaurus philologicus criticus linguae Hebraeae, s.v. גָּזָם; Yehuda Feliks, "Locust," Encyclopaedia Judaica (Keter, 1971); David Nevo, "The Desert Locust, Schistocerca gregaria, and Its Control in the Land of Israel and the Near East in Antiquity," Phytoparasitica 24 (1996): 7-32