Exodus 8:21

21. Swarms of flies The precise nature of this plague is doubtful . The word used, ערב , occurs only in this place and in the two psalms where this judgment is described, so that we get no aid in interpretation from parallel passages . The rendering of the Septuagint is dog-fly, an insect which in Egypt gives great annoyance to man and beast; and as the authority of that version is very high on Egyptian subjects, this is the most usual interpretation . These insects are described as coming in immense swarms, and settling in black masses on whatever part of the person of the traveller is exposed . Stuart Poole considers it to have been the domestic fly, which is now the most troublesome insect in Egypt . Hengstenberg quotes a traveller as saying: “Men and beasts are cruelly tormented by them . You can form no conception of their fury when they want to settle on any part of your body . You may drive them away, but they settle again immediately, and their obstinacy wearies out the most patient man . ” The distress arising from ophthalmia, now so common in Egypt, is much aggravated by the swarms of flies . Others, as Adam Clarke, Wordsworth, Kurtz, following a Jewish tradition, consider this plague to have been swarms of all kinds of noxious insects, and the author of the Book of Wisdom seems to have supposed that there were beasts also . ( Wis 11:15-16, etc.) Swarming creatures of some kind, probably of various species of insects, so afflicted Pharaoh that he yielded more than ever before, and consented to allow the Israelites to go into the wilderness and sacrifice. Further than this we cannot yet affirm.