Commentary for Exodus 10:19

רוח ים is A WEST WIND.

ויהפוך ה' רוח קדים, because the east wind had brought them from the west so that a west wind will bring them back to where they came from.

לא נשאר ארבה בגבולך, “not a single locust remained behind within the boundaries of your country.” The locusts, as opposed to the frogs at the time, did not die, the reason being that they had not come into existence for the purpose of this plague. They had merely been transported across a great distance, away from their natural habitat [this is all based on the opinion that the wordsותעל הצפרדע in 8,2 appears in the singular mode as opposed to the other occasions when this word appears in the plural mode. According to this view, a single frog became converted into millions of frogs for the sake of the plague, but after it had already left the river Nile. The frogs would therefore not have been able to “return” to their habitat, not having had a habitat in the first place. Ed.]