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The class of Gastropoda (the snails and slugs) is second only to insects in terms of total number of species. Slugs and garden (land) snails are air-breathing mollusks (Mollusca Gastropoda) although the common slug usually has no shell at all. Most are herbivorous, some are omnivorous and a few are carvivorus; they like to feast on almost any plant like vegetables, flowering plants, grain crops and fruit trees. If these are available, they are the preferred food for slugs and snails. However, they will also eat decaying matter, carrion and even mulch, compost or soil.
Land snails make up only a small percentage of gastropods; there are far more marine snails, both in the seas and in fresh water. There are many kinds found in freshwater; the ones here on my creek front lot are Planorbis carinatus, aquatic pulmonate gastropod mollusks in the family Planorbidae. They hibernate in winter, like most snails. Last week when I was transplanting raspberry canes, I found quite a few about one to two inches under the mulch. They were about the size of a dime. If you want to know more about freshwater snails, this site has a good “determination guide”.
Escargot in butter and garlic
Three varieties of snails for sale
Escargot, as the dish is generally known, is a dish of land snails usually cooked in garlic and butter, and often served as an appetizer. Most Americans have never eaten snails although we eat other mollusks like clams, oysters, scallops, mussels and less commonly, squid, octopus and abalone. Not all snails are edible. The ones that are edible have a lot of magnesium, phosphorus, potassium, Vitamin B1, Vitamin E and many essential amino acids. Except for the butter used in cooking, they are low in fat and calories.
Common brown snail (H. aspersa)
The farm-raised snails in the United States and France are usually Helix aspersa (Common, or Brown garden snail) or H. pomatia (the Escargot, Roman Snail, Burgundy Snail, or Edible Snail.) The H. aspersa, often called petit-gris, are about one-third the size of H. pomatia. Spanish cuisine also uses Otala punctata, Theba pisana and Iberus gualterianus alonensis. Farm-raised snails are fed a diet mainly of ground cereals or green and dried foods. They must have their digestive tract emptied (usually by fasting for several days) before cooking. The H. aspersa is common world-wide in temperate climates; you may have them in your yard. If so they can be captured in the wild (so to speak), and if thoroughly purged, may be eaten. It is a common practice in much of the world.
If you don’t want to eat them:
I doubt there are very many gardeners who have not purchased snail bait or Sluggo or some other chemical and spread it around their prized flowers or fruits and vegetables. The success varies, but by and large the snails and slugs ultimately win. That’s because of sheer numbers. Some snails are hermaphrodite (having both sex organs) although they usually mate. Mating takes from 2 hours to as much as a day, producing about 80 pearly-white eggs (from one-eighth of an inch to one-quarter an inch in diameter), which are deposited into crevices in the topsoil two weeks after mating.  They can do this up to six times a year, so the potential is 480 new snails for every two snails in your garden. Frequency of mating increases as the temperatures increase from spring into summer.
If you are interested in chemical control, Geoff Stein wrote a good article, Snail and slug control from a veterinary perspective. There are some non-chemical suggestions for snail and slug control. I have always heard to put down crushed eggshells as they don’t like to cross rough surfaces. Now I find that is a fallacy. The snails move by propelling themselves by their muscular foot through their trail of mucus. The mucus makes moving easier, and also protects them from injury from sharp objects. They can even ‘walk’ over razor blades without injury. A strip of copper about an inch wide totally enclosing an area will protect it from slugs and snails. Their motion through their own mucus over the copper strip builds up an electrical charge, which deters them.
One easy thing you can do is to eliminate their hiding places. That means cleaning up any debris, dead or decaying plant matter, empty pots, and any nooks and crannies. If you have storage in the yard, like a shed or even a deck, they will hide under it in the daytime. Keeping it cleared of all possible dark, damp spots will help. The other good thing you can do is be prepared to be merciless when you find these pests in your garden. Carry a salt shaker and salt any you see. Carry your garden clippers and cut any you see. Leave a small board outside overnight. Turn it up first thing in your morning walk and you will find slugs ready for slaughter.
Salting snails in the garden
Planorbis on chinese lantern
I have heard to sprinkle corn meal or oat bran around the garden. That doesn’t work for me because it usually rains right after I do that, or the dewfall is heavy enough to make it a sloppy mess. The beer trap idea does work, and I have a trick to doing it. I place three bricks on the ground, in a rough triangle. I fill a disposable pie pan halfway with beer… the yeastier the beer smells, the better because the snails/slugs are attracted to the yeast. Place the pie pan between the three bricks and lay a stepping-stone over the bricks. Now the neighborhood dogs (and children) cannot get to the beer, and rain won’t dilute it. Pick up the stepping-stone the next morning and you should have a pan of drowned slugs.
The Federal Plant Pest Act (PPA) defines a plant pest as "any living stage (including active and dormant forms) of insects, mites, nematodes, slugs, snails, protozoa, or other invertebrate animals, bacteria, fungi, other parasitic plants or reproductive parts thereof; viruses; or any organisms similar to or allied with any of the foregoing; or any infectious substances, which can directly or indirectly injure or cause disease or damage in or to any plants or parts thereof, or any processed, manufactured, or other products of plants..."  This act was replaced as part of the Agricultural Risk Protection Act, which became law in June 2000.
Escargots au beurre d’ail (Escargot in butter and garlic)
1 tablespoon (6 grams) parsley, finely minced
1 teaspoon (6 grams) shallot, finely minced
1 tablespoon (9 grams) garlic, finely minced
1/4 teaspoon (2 grams) salt
1/4 teaspoon (1 gram) freshly ground black pepper
1/2 tablespoon white wine
1 teaspoon cognac
a dash of nutmeg
6 tablespoons (90 grams) butter, softened
12 escargots de Bourgogne
Pound parsley, shallot and garlic in a mortar into a paste. Combine with salt, pepper, wine, cognac, and nutmeg. Combine with butter. Alternately, place parsley, shallot, garlic, salt, pepper, wine, cognac, and nutmeg in the bowl of a mini-food processor and process until minced. Add butter and process to combine.
Preheat oven to 450° F.
Arrange snails in individual wells of escargot plates. Top each with 1/12 of the escargot butter. Bake for 9 minutes, or until snails are warm.
Yield: 2 servings.
Source: Jean-Pierre Silva, Hostellerie du Vieux Moulin, Bouilland, France, 1997.
 Bezemer T. M. & Knight K. J. 2001. Unpredictable responses of garden snail Helix aspersa populations to climate change. Acta Oecologica, 22, 201-208
Escargot bordeaux.jpg is licensed under the Creative Commons Attribution 3.0 Unported License. The author is Kadooshka.
Helix aspersa on greens GNU Free Documentation License, Version 1.2 Planorbis shells is in the public domain
Planorbis on rock, GNU Free Documentation License, Version 1.2
A Snail (Helix aspersa) in Balboa Park is in the public domain. www.pdphoto.org
Grapevine snail (Helix pomatia) GNU Free Documentation License, Version 1.2
Common variety snail Helix aspersa is licensed under Creative Commons Attribution 2.0 License.
Slug, GNU Free Documentation License, Version 1.2
Escargot Appetizer with Fork, iStockphoto #: 8170769, Used by Permission
Snail on Salad, iStockphoto #: 1965750 Used by Permission
Salt shaker over snails iStockphoto #: 2899323 Used by Permission
Strolling snails, iStockphoto #: 1824684 Used by Permission
Market snails in Italy, GNU Free Documentation License, Version 1.2