וַיֹּ֨אמֶר יְהוָ֜ה אֶל־מֹשֶׁ֗ה נְטֵ֨ה יָדְךָ֜ עַל־אֶ֤רֶץ מִצְרַ֙יִם֙ בָּֽאַרְבֶּ֔ה וְיַ֖עַל עַל־אֶ֣רֶץ מִצְרָ֑יִם וְיֹאכַל֙ אֶת־כָּל־עֵ֣שֶׂב הָאָ֔רֶץ אֵ֛ת כָּל־אֲשֶׁ֥ר הִשְׁאִ֖יר הַבָּרָֽד׃
I rzekł Wiekuisty do Mojżesza: "Wyciągnij rękę twoję na ziemię Micraim o szarańczę, aby napadła na ziemię Micraim i pożarła wszelkie zioła ziemi, wszystko co zostawił grad."
Tze'enah Ure'enah
“Hold out your arm over the land of Egypt for the locusts” [10:12]. The Holy One said to Moses: Hold out your hand over the land of Egypt and locusts will come over the land of Egypt. Moses held out his hand and God caused a great wind to blow from the east for a whole day and night. The wind brought the locusts over the whole land of Egypt and there were so many locusts that they covered the whole land of Egypt. It was dark because of so many locusts. They ate all the vegetation and grain. Therefore, locusts are mentioned seven times in the Torah portion, since there were all sorts of locusts, large and small, red, black, white, green and brown.6Bahya, Exodus, 10:14.
Rashi
בארבה means on account of the plague of locusts (the prefix ב signifies “on account of”).
Sforno
על ארץ מצרים בארבה. A reference to the region from which the locusts generally came, i.e from the southern part of the continent. We have references of this kind in Isaiah 5,26 describing that these locusts traveled long distances before arriving in Egypt.