Yeremia 46:20

46:20 Egypt is like a beautiful young cow.

But northern armies will attack her like swarms of stinging flies. ¹ 

[46:20]  ¹ tn Heb “Egypt is a beautiful heifer. A gadfly from the north will come against her.”
The metaphors have been turned into similes for the sake of clarity. The exact meaning of the word translated “stinging fly” is uncertain due to the fact that it occurs nowhere else in Hebrew literature. For a discussion of the meaning of the word which probably refers to the “gadfly,” which bites and annoys livestock, see W. L. Holladay, Jeremiah (Hermeneia), 2:331, who also suggests, probably correctly, that the word is a collective referring to swarms of such insects (cf. the singular אַרְבֶּה [’arbeh] in v. 23 which always refers to swarms of locusts). The translation presupposes the emendation of the second בָּא (ba’) to בָּהּ (bah) with a number of Hebrew mss and a number of the versions (cf. BHS, fn b).