Midrash su Esodo 10:20

"And YHVH shifted a sea-wind...[and not one locust remained]" (Exodus 10:19) What is "not one locust remained"? Rabbi Yochanan said: since the Egyptians rejoiced when the locusts came. They said, "Let us gather and fill barrels up of them." The Holy One Blessed Be He said, "Evildoers! With the plague that I brought upon you, you rejoiced in it!" Immediately, "And YHVH shifted a very strong sea-wind". This is a western wind. "And He lifted the locusts..." (Exodus 10:19) What is "not one locust remained"? Even those that had been pickled in their pots and barrels flew away and went to them. "And YHVH strengthened the heart of Pharaoh" (Exodus 10:20)