The warning presented to Pharaoh is a stark ultimatum: continued defiance will trigger an unprecedented invasion, devastating whatever economic and territorial security Egypt has left [קאסוטו]. Pharaoh's stance is not merely a reluctance to free the Israelites, but an act of absolute refusal and complete rebellion [פרדס יוסף]. The impending threat is a massive swarm of locusts, an insect named specifically for its sheer multitude, as it outnumbers all other living species [אבן עזרא].
The arrival of locusts in Egypt is a highly irregular event. These small, leaderless insects do not typically migrate there, as the land lacks their natural pasture. Therefore, their sudden appearance is a profound miracle designed specifically to humiliate Pharaoh's arrogant heart [ביאור יש"ר]. This reality dismisses any notion that Moses simply observed the natural approach of an incoming swarm; had it been a normal phenomenon, the Egyptians would have noticed it as well and would not have viewed it as miraculous [שד"ל].
Moses declares that the invasion will strike the very next day. Setting the plague for the following day allows the east wind to blow continuously for a full day and night, bringing the swarm through seemingly natural forces [העמק דבר]. Additionally, the timing is an act of exact retribution. During the plague of frogs, Pharaoh asked Moses to delay removing the frogs until the next day, willfully extending the suffering of his people just to test God. In response, God schedules this new disaster for the exact same timeframe [שפתי כהן].
The primary approach among commentators is that roughly one month passes between the plague of hail and the arrival of the locusts, fitting into the twelve-month duration of the plagues. The hail struck in the month of Adar, destroying the early-ripening barley and breaking the dormant tree branches, but leaving the late-ripening wheat and spelt unharmed. A month later, in Nisan, the wheat had grown and the trees had just begun to blossom. The locusts arrive precisely at this moment to consume the fresh blooms and the final remnants of the crops that survived the hail [רמב״ן, הטור הארוך].
The warning specifically targets the borders of the nation, carrying deep psychological weight. Despite the devastation of the hail, Pharaoh still maintains a sense of security because his national borders and the foundational wealth of his country remain intact. This new plague is designed to penetrate that safe haven and entirely shatter his illusion of control [רש"ר הירש]. Furthermore, the invasion serves a geopolitical purpose. At the time, Egypt was engaged in border disputes with neighboring nations. Miraculously, the locusts swarm exclusively within the original borders of Egypt, stopping exactly at the boundary line. This precise targeting reveals the true borders of the state to the world, delivering a profound lesson in divine justice [חתם סופר].
Uniquely, the narrative launches directly into Moses issuing the warning, without first recording God's command to him. Some suggest Moses deduced the nature of the next plague on his own, either because God had previously revealed all the plagues to him, or because he recognized a specific phrase from God regarding telling future generations, which is historically associated with locusts. However, the accepted explanation is that God did explicitly command Moses, but the narrative is simply condensed to avoid repetition. By omitting the initial divine instruction, the focus shifts directly to the execution of the mission and the dramatic dialogue that unfolds between Pharaoh, Moses, and the royal advisors [פענח רזא, הדר זקנים].