Exodus 10:12

This is no unusual plague in Africa and Arabia, where, when the harvest is ripe, they frequently come in vast numbers, and upon all their corn, and what they do not eat they infect with their touch, and the moisture coming from them, and afterwards dying in great numbers, they poison the air, and cause a pestilence. So that it is no wonder that Pharaoh and his servants were so concerned for this plague, so well known to them, especially considering that this was like to be far worse than all of the same kind which they had either seen or heard of.