Because they had said to the Israelites, "Go and sweep and clean our houses, our courtyards, and our streets," He changed the dust of the air into lice, so that the vermin lay piled up in heaps an ell high, and when the Egyptians put on fresh garments, they were at once infested with the insects.
The fourth plague was an invasion of the land by hordes of all sorts of wild animals, lions, wolves, panthers, bears, and others. They overran the houses of the Egyptians, and when they closed their doors to keep them out, God caused a little animal to come forth from the ground, and it got in through the windows, and split open the doors, and made a way for the bears, panthers, lions, and wolves, which swarmed in and devoured the people down to the infants in their cradles. If an Egyptian entrusted his ten children to an Israelite, to take a walk with them, a lion would come and snatch away one of the children, a bear would carry off the second, a serpent the third, and so on, and in the end the Israelite returned home alone. This plague was brought upon them because they were in the habit of bidding the Israelites go and catch wolves and lions for their circuses, and they sent them on such errands, to make them take up their abode in distant deserts, where they would be separated from their wives, and could not propagate their race.