Over the land; over divers parts of the land, shaking his rod towards the several quarters of it. An east wind in those parts is a most violent and pernicious wind, Exo_14:21Num_11:31, and a dry wind, and therefore fit for the engendering of those creatures. This wind brought them from Arabia, where they are in great numbers, as we have seen, Exo_10:12, though God miraculously increased their numbers, and their power of doing mischief.