And the Lord did so,.... And this he did immediately of himself without any means; not by the rod of Aaron, to let the Egyptians see that there was nothing in that rod, that it had no magic virtue in it, and what was done by it was from the Lord himself, who could as well inflict plagues without it as with it; see Psa 105:31 and there came a grievous swarm of flies; or a "heavy" (q) one, which was both very numerous, and very troublesome and distressing: into the house of Pharaoh, and into the houses of his servants, and into all the land of Egypt: into the palace of Pharaoh, and into the palaces of his nobles, ministers, and courtiers, and into the dwelling places of all his subjects, throughout the whole land, excepting the land of Goshen: the land was corrupted by reason of the swarm of flies; Josephus (r) says, the land lay neglected and uncultivated by the husbandmen; it may be, the air was infected by the flies, which produced a pestilence that took off many of the inhabitants; so among the Eleans, as Pliny (s) reports, a multitude of flies produced a pestilence; however, it is certain many of the inhabitants of Egypt perished by them; they might sting them to death, suck their blood, and poison them with their envenomed stings; see Psa 78:45. (q) "gravis", Montanus, "gravissime", V. L. (r) Ut supra. (Antiqu. l. 2. c. 14. sect. 3.) (s) Nat. Hist. l. 10. c. 28.