What snails eat

A garden snail is not a tiny cow, and it is not only a pest of lettuce. The radula can rasp living leaves. Seedlings suffer because one night of feeding removes a large share of a very small plant. The same ribbon of teeth takes algae off a wall, fungi, decaying leaves, and the softened flesh of fallen fruit. Many land snails are grazers and detritivores that sometimes eat crops, rather than strict herbivores. Carrion, the eggs of other snails, and empty shells, for the calcium in them, are food for some species. A few land snails are hunters. The rosy wolf snail is one. So is the decollate snail, which has been sold, unwisely, as a living pesticide.

What a snail is able to eat and what it takes first are different. Soft, damaged, or already decaying tissue is easier than a dry intact leaf. People still sink beer traps because the smell of yeast overlaps with overripe fruit, not because snails are drinkers. Poison baits work because they are food with a toxin added, metaldehyde in the older products and iron phosphate in the less reckless ones. Iron phosphate is the better of those two if a bait is genuinely required, and the label still matters. Night picking, and a band of copper tape around one raised seed tray, will often save the seedlings without a broadcast poison.

Calcium is a separate hunger. A snail on a mortar joint may be feeding on lime. Crushed eggshells vanish from a compost heap for the same reason. If you are defending a seedbed, a sacrificial source of calcium away from the row is a more precise offer than letting the wall, or the seedlings, be the only mineral in reach.

Salt is not a food and not a control. It kills by pulling water out of a soft body, and it salts the soil it touches. A tip that begins with a handful of salt is describing an injury, then calling it gardening.