Flies — Or insects of various kinds; not only flies, but gnats, wasps, hornets; and those probably more pernicious than the common ones were.
Related Commentaries of Exodus 8:21
Exodus 8:21
21 Else, if thou wilt not let my people go, behold, I will send swarmsd 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.