Charles Ellicott Commentary Joel 2:3

"A fire devoureth before them; and behind them a flame burneth: the land is as the garden of Eden before them, and behind them a desolate wilderness; yea, and none hath escaped them." — Joel 2:3 (ASV)

Before them ... behind them.— As with the locusts, so with the invading hosts of enemies: the country is found a paradise, and left a desert.