Charles Ellicott Commentary Joel 2:4

"The appearance of them is as the appearance of horses; and as horsemen, so do they run." — Joel 2:4 (ASV)

As the appearance of horses.— So also are locusts described in the Revelation: And the shapes of the locusts were like unto horses prepared unto battle (from this likeness the Italians call a locust cavalletta) ... and the sound of their wings was as the sound of chariots, of many horses running to battle (Revelation 9:7, 9:9).