Swarms of flies - Generally, supposed to be the dog-fly, which at certain seasons is described as a plague far worse than mosquitos. Others, however, adopt the opinion that the insects were a species of beetle, which was reverenced by the Egyptians as a symbol of life, of reproductive or creative power. The sun-god, as creator, bore the name Chepera, and is represented in the form, or with the head, of a beetle.

Swarms of flies upon thee - It is not easy to ascertain the precise meaning of the original word הערב hearob; as the word comes from ערב arab, he mingled, it may be supposed to express a multitude of various sorts of insects. And if the conjecture be admitted that the putrid frogs became the occasion of this plague, (different insects laying their eggs in the bodies of those dead animals, which would soon be hatched, see on Exodus 8:14 (note)), then the supposition that a multitude of different hinds of insects is meant, will seem the more probable. Though the plague of the locusts was miraculous, yet God both brought it and removed it by natural means; see Exodus 10:13-19.

Bochart, who has treated this subject with his usual learning and ability, follows the Septuagint, explaining the original by κυνομυια, the dog-fly; which must be particularly hateful to the Egyptians, because they held dogs in the highest veneration, and worshipped Anubis under the form of a dog. In a case of this kind the authority of the Septuagint is very high, as they translated the Pentateuch in the very place where these plagues happened. But as the Egyptians are well known to have paid religious veneration to all kinds of animals and monsters, whence the poet: -

Omnigenumque deum monstra, et latrator Anubis,

I am inclined to favor the literal construction of the word: for as ערב ereb, Exodus 12:38, expresses that mixed multitude of different kinds of people who accompanied the Israelites in their departure from Egypt; so here the same term being used, it may have been designed to express a multitude of different kinds of insects, such as flies, wasps, hornets, etc., etc. The ancient Jewish interpreters suppose that all kinds of beasts and reptiles are intended, such as wolves, lions, bears, serpents, etc. Mr. Bate thinks the raven is meant, because the original is so understood in other places; and thus he translates it in his literal version of the Pentateuch: but the meaning already given is the most likely. As to the objection against this opinion drawn from Exodus 8:31, there remained not one, it can have very little weight, when it is considered that this may as well be spoken of one of any of the different kinds, as of an individual of one species.

Else, if thou wilt not let my people go,.... But remainest obstinate and inflexible:

behold, I will send swarms of flies upon thee; the word used is generally thought to signify a "mixture", and is interpreted by many a mixture of various creatures; the Targum of Jonathan paraphrases it a mixture of wild beasts, and so Josephus (k) understands it of all sorts of beasts, of many forms, and such as were never seen before; according to Jarchi, all sorts of evil beasts are meant, as serpents and scorpions, mixed together; and so Aben Ezra says it signifies evil beasts mixed together, as lions, wolves, bears, and leopards; but it is not likely the houses should be filled with these, or the ground covered with them, as after related: and besides, they would soon have destroyed, all the inhabitants of the land, since as it follows they are said to be upon them; rather a mixture of insects is intended; the Septuagint; version renders it the "dog fly", and so Philo the Jew (l); which, as Pliny (m) says, is very troublesome, to dogs especially, about their ears, and this version Bochart (n) approves of:

and upon thy servants, and upon thy people, and into thy houses; they should be sent unto and settle first on his own person, and also on his ministers and courtiers, and upon all his subjects in general, and get into their houses, and be very troublesome guests there:

and the houses of the Egyptians shall be full of the swarms of flies, and also the ground whereon they are; their number would be so very great.

(k) Antiqu. l. 2. c. 14. sect. 3.((l) De Vita Mosis, l. 1. p. 622. (m) Nat. Hist. l. 11. c. 34. (n) Hierozoic. par. 2. l. 4. c. 15. col. 555.

Else, if thou wilt not let my people go, behold, I will send swarms of flies upon thee, and upon thy servants, and upon thy people, and into thy houses: and the houses of the Egyptians shall be full of swarms of flies, and also the ground whereon they are.

8:21 Flies - Or insects of various kinds; not only flies, but gnats, wasps, hornets; and those probably more pernicious than the common ones were.

swarms...: or, a mixture of noisome beasts, etc

8:20-32 Pharaoh was early at his false devotions to the river; and shall we be for more sleep and more slumber, when any service to the Lord is to be done? The Egyptians and the Hebrews were to be marked in the plague of flies. The Lord knows them that are his, and will make it appear, perhaps in this world, certainly in the other, that he has set them apart for himself. Pharaoh unwillingly entered into a treaty with Moses and Aaron. He is content they should sacrifice to their God, provided they would do it in the land of Egypt. But it would be an abomination to God, should they offer the Egyptian sacrifices; and it would be an abomination to the Egyptians, should they offer to God the objects of the worship of the Egyptians, namely, their calves or oxen. Those who would offer acceptable sacrifice to God, must separate themselves from the wicked and profane. They must also retire from the world. Israel cannot keep the feast of the Lord, either among the brick-kilns or among the flesh-pots of Egypt. And they must sacrifice as God shall command, not otherwise. Though they were in slavery to Pharaoh, yet they must obey God's commands. Pharaoh consents for them to go into the wilderness, provided they do not go so far but that he might fetch them back again. Thus, some sinners, in a pang of conviction, part with their sins, yet are loth they should go very far away; for when the fright is over, they will turn to them again. Moses promised the removal of this plague. But let not Pharaoh deal deceitfully any more. Be not deceived; God is not mocked: if we think to cheat God by a sham repentance and a false surrender of ourselves to him, we shall put a fatal cheat upon our own souls. Pharaoh returned to his hardness. Reigning lusts break through the strongest bonds, and make men presume and go from their word. Many seem in earnest, but there is some reserve, some beloved, secret sin. They are unwilling to look upon themselves as in danger of everlasting misery. They will refrain from other sins; they do much, give much, and even punish themselves much. They will leave it off sometimes, and, as it were, let their sin depart a little way; but will not make up their minds to part with all and follow Christ, bearing the cross. Rather than that, they venture all. They are sorrowful, but depart from Christ, determined to keep the world at present, and they hope for some future season, when salvation may be had without such costly sacrifices; but, at length, the poor sinner is driven away in his wickedness, and left without hope to lament his folly.