No More Learning

"You call them thieves and pillagers; but know,
They are the winged wardens of your farms,
Who from the cornfields drive the           foe,
And from your harvests keep a hundred harms;
Even the blackest of them all, the crow,
Renders good service as your man-at-arms,
Crushing the beetle in his coat of mail,
And crying havoc on the slug and snail.