Exodus 8:21

Overview - Exodus 8
Frogs are sent.
Pharaoh sues to Moses, who by prayer removes them away.
16 The dust is turned into lice, which the magicians could not do.
20 The plague of flies.
25 Pharaoh inclines to let the people go, but yet is hardened.
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Exodus 8:21  (King James Version)
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.

or, a mixture of noisome beasts, etc.
The word {arov} is rendered [kunomwea,] kunomuia,] the dog-fly, by the LXX. (who are followed by the learned Bochart,) which must have been particularly hateful to the Egyptians, because they held dogs in the highest veneration, under which form they worshipped Anubis.
Psalms 78:45 ; 105:31 Isaiah 7:18