New Defender's Study Bible Notes
9:7 like unto horses. See Joel 2:4-5 (also note Revelation 9:9 here). Evidently Joel, who prophesied very graphically of the coming day of the Lord, also had received a vision of this invading swarm of locust-like demons. Part of his prophecy deals with an actual invasion of the land by real locusts, but, as often happens in the Old Testament prophetical books, the immediate vision yields to a vision of far-future events, the first being merely a type of the much greater event yet to come.