A divine promise assures the complete removal of a devastating threat, scattering it into desolate wastelands. The primary approach among commentators identifies this threat as a massive locust plague. Unusually, this swarm attacks from the north, deviating from typical migration patterns that originate in the south or east [ביאור שטיינזלץ]. God promises to banish these insects to a barren desert where, devoid of food, they will starve [רד״ק, אבן עזרא, מצודת דוד]. Because the swarm is unimaginably large, divine winds will split and scatter it in opposite directions. The vanguard will be driven into the eastern waters, such as the Dead Sea or the Sea of Galilee, while the rear guard will be swept into the western waters of the Mediterranean [רוב הפרשנים].
As millions of insects perish in the arid wilderness, an overwhelming stench will rise from their decay. While this foul odor emphasizes the sheer scale of the rotting mass, some note a specific distinction in the decay: the stench arises both from the rotting corpses that pollute the air with disease and from the spoiled eggs and remnants the locusts leave behind [מלבי״ם]. The complete eradication of this swarm occurs because of the immense scale of its actions. The insects caused such profound devastation that God is moved to mercy [רד״ק, ביאור שטיינזלץ, מצודת דוד]. From another perspective, the plague is removed because it has successfully fulfilled its purpose of awakening the people to repentance, making further affliction unnecessary [מלבי״ם].
Beyond the physical insect plague, the invading force from the north also represents the historical armies of the Assyrian kings, whose troops God will similarly scatter to the east and west [רש״י]. On a deeper spiritual level, this northern threat symbolizes the evil inclination, which lies hidden within the human heart. God will ultimately banish this internal adversary to a desolate place where there are no people to tempt [רד״ק]. In this spiritual context, the eastern and western seas represent the First and Second Temples. The evil inclination directed its efforts toward these holy sites, causing the nation to sin and ultimately bringing about their destruction [רש״י, רד״ק].
The magnitude of the evil inclination's actions is understood through its ambitious targets; it specifically attacks the greatest individuals, focusing its temptations on Torah scholars [רש״י, רד״ק]. Furthermore, its methods are marked by sophisticated deceit. Rather than directly tempting a person with an obvious sin that would surely be rejected, it encourages the performance of a Commandment, such as waking early to attend synagogue. Its true intention is to create opportunities for a person to stumble along the way through improper thoughts or harmful gossip. Because it abuses God's Commandments to trap individuals, the foul stench of its deceit rises, sealing its doom [חומת אנך]. Ultimately, eradicating the evil inclination addresses the root cause of sin, which naturally leads to the removal of the physical locust plague that served only as the resulting punishment [מלבי״ם].