Charles Ellicott Commentary Exodus 8:24

"And Jehovah did so; and there came grievous swarms of flies into the house of Pharaoh, and into his servants` houses: and in all the land of Egypt the land was corrupted by reason of the swarms of flies." — Exodus 8:24 (ASV)

The land was corrupted. —Rather, as in the margin, destroyed. Kalisch observes, “These insects”—that is, the kakerlaque (Blatta Orientalis), “really fill the land and trouble humans and animals; they consume all sorts of materials, devastate the country, and are insofar more detrimental than the gnats, as they also destroy the property of the Egyptians.”