What exactly, was the plague of Arov?
Rashi and Targum Yonasan: It comprised a mixture 1 of wild animals, including snakes and scorpions, which killed the Egyptians.
Rashbam: It was a mixture of different species of wolves, which generally attack in packs at nighttime. 2
What is the significance of the phrase "u'Mal'u Batei Mitzrayim es he'Arov"?
Oznayim la'Torah: IN spite of the fact that the Egyptians fled to their homes and bolted all the doors, the wild animals found way to break into their houses. 1
Oznayim la'Torah (citing Seifer ha'Yashar): Hashem sent sirens from the sea to open the doors.
What is the significance of the phrase "and also the ground upon which they are"?
Seforno: This means that the ground upon which the houses stand will be filled with snakes and wild creatures that dwell underground. 1
Divrei Eliyahu and Kol Eliyahu: This hints at the Yid'oni, a ferocious beast attached to the ground by means of a sort of umbilical cord. It too, appeared in Egypt, together with the earth to which it was attached. 2
Oznayim la'Torah: The distinction that Hashem will make between Yisrael and the Egyptians will extend to the ground