The Lord shall hiss (see Isaiah 5:26, and note ad loc.). For the fly that is in the uttermost part of the rivers of Egypt. The "fly of Egypt," like the "bee of Assyria," represents the military force of the nation, which God summons to take part in the coming affliction of Judaea.
The prophetic glance may be extended over the entire period of Judah's decadence, and the "flies" summoned may include those which clustered about Neco at Megiddo, and carried off Jehoahaz from Jerusalem (2 Kings 23:29-34).
There may be allusion also to Egyptian ravages in the reigns of Sargon, Sennacherib, and Esar-haddon. In any general review of the period we shall find it stated that, from the time of Sargon to that of Cyrus, Judaea was the battle-ground upon which the forces of Assyria (or Assyro-Babylonia) and Egypt contended for the empire of western Asia.
The desolation of the land during this period was produced almost as much by the Egyptian "fly" as by the Assyrian "bee." The "rivers of Egypt" are the Nile, its branches, and perhaps the great canals by which its waters were distributed.
The bee that is in the land of Assyria. The choice of the terms "bee" and "fly," to represent respectively the hosts of Assyria and Egypt, is not without significance. Egyptian armies were swarms, hastily levied, and very imperfectly disciplined.
Assyrian were bodies of trained troops accustomed to war, and almost as well disciplined as the Romans.