And the LORD said unto Moses, Rise up early in the morning, and stand before Pharaoh; lo, he cometh forth to the water; and say unto him, Thus saith the LORD, Let my people go, that they may serve me.
Rise up early ... Pharaoh; lo, he cometh ... Pharaoh still appearing obdurate, Moses was ordered to meet him while walking on the banks of the Nile, and repeat his request for the liberation of Israel, threatening, in case of continued refusal, to cover every house, from the palace to the cottage, with swarms of flies х `aarob (H6157)]; while, as a proof of the power that accomplished this judgment, the land of Goshen should be exempted from the calamity. The appeal was equally vain as before; and the predicted evil overtook the country in the form of what was not "flies" such as we are accustomed to, but, as the original word signifies, a mingling, divers sorts of flies (Psalms 78:45) - the gad-fly, the dog-fly, the cockroach, the Egyptian beetle-for all these are mentioned by different writers. Flies succeed gnats in ordinary seasons; and in consequence of the dampness of the air for a considerable portion of the year, flies, fleas, and bugs are plentiful. They are very destructive, some of them inflicting severe bites on animals, others destroying clothes, books, plants, everything. The worship of flies, particularly of the beetle (scarabacus), was a prominent part of the religion of the ancient Egyptians.
Moreover, the tutelary deity of Lower Egypt was worshipped under the symbol of a winged asp (Wilkinson's 'Ancient Egypt,' vol. 5:, pp. 45, 84). The employment of these winged deities to chastise them must have been painful and humiliating to the Egyptians, while it must at the same time have strengthened the faith of the Israelites in the God of their fathers as the only object of worship.