For a nation is come up upon my land, strong, and without number, whose teeth are the teeth of a lion, and he hath the cheek teeth of a great lion.
For a nation - applied to the locusts, rather than "people" (Proverbs 30:25-26), to mark not only their numbers, but also their savage hostility; and also to prepare the mind of the hearer for the transition to the figurative locusts in Joel 2:1-32 - namely, the "nation" or Gentile foe х gowy (H1471)] coming against Judea (cf. Joel 2:2, "a great people and a strong").
Is come up upon my land - i:e., Yahweh's; which never would have been so devastated were I not pleased to inflict punishment (Joel 2:18; Isaiah 14:25; Jeremiah 16:18; Ezekiel 36:5; Ezekiel 38:16).
Strong as irresistibly sweeping away before its compact body the fruits of man's industry.
Without number - so Judges 6:5; Judges 7:12, the Midianites are said to be "like grasshoppers (or locusts) for multitude." So also the Babylonians (Jeremiah 46:23), and the Assyrians (Nahum 3:15).
Whose teeth are the teeth of a lion - i:e., the locusts are as destructive as a lion; there is no vegetation that can resist their bite (cf. Revelation 9:8, which is derived from Joel here, and applies the image to invaders far worse than insects). Pliny says 'they gnaw even the doors of houses.' Their two jaws are armed with saw-like teeth like the eye teeth of the lion and lioness.