Revelation 9:9
And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle.
Cross-reference
Joel 2:5–7
Allusion
Joel 2:5-7 directly compares locusts to chariots and warriors—the exact same imagery of wing-sound like chariots and orderly advance.