This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
Procure a gallon or two of wheaten bran, or brewer's grains, and on a mild evening, just before or after a shower, place little patches of it about the garden in all directions, especially near box-edgings and similar places of retreat. About nine o'clock at night, provided with a good lantern and candle, and armed with a potful of air-slaked lime, visit all the little patches of bran in succession; you will probably be astonished at the vast numbers of these enemies congregated and feasting at your expense, when, with the pot of lime, you can give them such a dusting as will prevent them from ever again troubling you. If this plan be persevered in for a short time, the garden will be effectually cleared of slugs. I have applied this remedy for many years, and have never known it to fail. - H. Mitchell.
Ducks are said to be great destroyers of slugs and other vermin. Young broods may be allowed to wander about the garden every evening, and it is amusing to see the seal with which they attack the enemy; but quick-lime, used so as not to disfigure the garden (say one peck per acre), if quick and fresh, is an excellent remedy.