וְאָ֨נֹכִ֜י הִשְׁמַ֤דְתִּי אֶת־הָֽאֱמֹרִי֙ מִפְּנֵיהֶ֔ם אֲשֶׁ֨ר כְּגֹ֤בַהּ אֲרָזִים֙ גָּבְה֔וֹ וְחָסֹ֥ן ה֖וּא כָּֽאַלּוֹנִ֑ים וָאַשְׁמִ֤יד פִּרְיוֹ֙ מִמַּ֔עַל וְשָׁרָשָׁ֖יו מִתָּֽחַת׃
Yet destroyed I the Amorite before them, Whose height was like the height of the cedars, And he was strong as the oaks; Yet I destroyed his fruit from above, And his roots from beneath.
Rashi on Amos
his fruit from above—I.e, the celestial princes. [from Midrash Tanchuma, Devarim 4; Tanchuma Buber, Addendum to Devarim 8]
Rashi on Amos
and his roots from below—I. e, the earthly princes. Another explanation: the wasp would blind their eyes from above and castrate them from below. [from Sotah 36a]