The appearance of them [is] as the appearance of horses,.... in their running, as Jarchi and Kimchi interpret it; they came with, as much swiftness and eagerness, with as much fierceness and courage, as horses rush into the battle.
Bochart has shown, from various writers, that the head of a locust is in shape like that of a horse; and Theodoret on the text observes, that whoever thoroughly examines the head of a locust will easily perceive that it is very like the head of a horse; see Re 9:7.
The Chaldeans are often represented as strong and mighty, fierce and furious, and riding on horses exceeding swift, Jer 4:13;and as horsemen, so shall they run; with great agility and swiftness. The particle "as" is observed by some, against those interpreters that apply this wholly to the enemies of the Jews, and not the locusts; and it seems indeed best to favour them; but Theodoret observes, that the "as" here may be taken, not as a note of similitude, but as used for the increase and vehemency of the expression.
Hierozoic. par. 2. l. 4. c. 5. p.