Gardening : War on Snails: Shelled Invaders a Tough Foe : Voracious garden pests can be controlled but never eradicated, experts say.
Coffee mug in hand, I slid open the glass door and stepped out onto the cool brick patio. It was early July, our first morning in the house we’d bought in Thousand Oaks. The sun was just peeking out from behind the hillside to the east, and the lawn glistened with early morning dew.
I glanced at the vegetable garden that bordered one side of our back yard. We’d inherited the carefully tended plot from the previous owners. Now the strawberries, zucchini, tomatoes, and other delicacies were ours to nurture and enjoy. Gardening would be a new adventure for my wife and I, who were longtime apartment and condo dwellers. We were eager to plunge ahead.
I took a step toward the garden, and my buoyant mood instantly evaporated. A soft, crunching sound was accompanied by a slimy, oozing sensation under the ball of my bare foot. I looked down, already guessing the obvious: I’d stepped on a snail.
Unfortunately, it wasn’t the only one. Silvery trails snaked all over the patio. And the garden! Shelled invaders were everywhere--hanging from the strawberry plants, slithering across the zucchini, clinging to the tomatoes.
After wiping my foot on the grass, I slouched back inside. “What’s wrong?†my wife asked, reacting to my look of dismay.
“We’ve been slimed,†I replied.
Thriving in Southland
The common garden snail, that nemesis of back-yard horticulturists everywhere, is no stranger to Southern California. Indeed, despite our dry, sunny climate--seemingly hostile to a creature that covets a damp, humid environment--snails and slugs (their non-shelled kin) thrive in the Southland.
“The reasons are simple,†said Don Zimmerman, assistant general manager for Armstrong Garden Centers. “The flowers, plants and vegetables in our yards provide an abundant food source. Sprinklers provide more than adequate moisture. And we don’t have frigid winters that kill snails off or drive them into hibernation.â€
Snails and slugs are members of the mollusk family, relatives of the more desirable abalone, clam and oyster. A native of Europe, the garden snail was most likely brought to North America by early French settlers, who, like their modern-day descendants, coveted the creature for food. (Yes, the snail you pick off your ivy is the same type you get at fancy restaurants.)
Since those early days, the garden snail has managed to blanket most of the continental United States. Here in the West they are regarded as one of the worst of garden pests, Zimmerman said.
Have Rasping Mouths
Snails and slugs feed on a wide variety of plants, cutting holes in foliage, leaves, fruits and stems with their rasping mouths, located on the underside of their bodies.
“They eat flower petals, the tender foliage of young shoots, and most kinds of leaves,†Zimmerman said. “They’ll even eat citrus leaves. I’ve found snails way up in the tops of 25-foot-tall orange trees.â€
“There are very few plants that snails won’t munch on,†added Bill Hicks, a horticultural pest control specialist with the landscape department of the Los Angeles Unified School District. “They especially love ivy. Ivy gives them food and a perfect hiding place all in one.â€
Snails are active mostly at night, when it’s cool and damp--just the time when many people choose to kick on their sprinklers. During the day they seek shelter from the sun, hiding under leaves, rocks or other yard and garden debris.
Although they are a year-round presence in Southern California, the snail and slug population does tail off from late October to early February. (Even the mild California winters are cold enough to drive some of them underground into hibernation.) The summer months of July through September are the peak season.
Control, Not Eradication
So what can you do to combat these slimy pests? Are your gardens and flower beds forever at their mercy?
Not at all. Several effective methods of snail control exist. That’s control, mind you, not eradication.
“Nobody ever gets rid of slugs and snails for good,†said Zimmerman, who has 45 years’ experience in the nursery business. “They’ll return from neighbors’ yards or hatch from eggs in containers of new plants or new soil. The best you can do is keep their numbers down--and even that is an ongoing battle.â€
There are several effective snail control methods to choose from--some fairly straight forward, and some a bit off-the-wall.
Baiting: Poisoning is the most widely used method of snail abatement. Commercial snail baits--in pellets, meal or emulsion form--are available from most nurseries and garden stores. These contain the chemicals metaldehyde and/or mesurol, which will attract and effectively dispatch slugs and snails.
Pellets are by far the most popular and easiest form of snail bait to apply. The pellets should be spread around your garden and flower beds in the evening, preferably just after watering. Scatter them rather than making piles. One application every 10 days or so in peak season should be adequate.
Baiting is a simple procedure, but it does have drawbacks. The bait is poisonous to other creatures besides snails, including pets and humans. For that reason, it is best to avoid the pellets and use meal if you have dogs or small children who might ingest them. And never apply either form directly on garden vegetables.
Gathering: Simple hand picking is perhaps the easiest way to control snails in your garden--and as a bonus, it’s completely nontoxic. You simply grab the invaders by the shells and dispose of them.
The best hunting time is after 10 p.m. Head out to the garden with a flashlight and coffee can, and go to it. Yes, the snails may try to crawl out of the can. But an inch or two of soapy water in the bottom will cause the critters to ball up inside their shells.
The drawback to collecting is that you have to touch the slimy things. Having no shells to grab onto, slugs are especially loathsome, and harder to pick up than snails.
If you simply can’t bring yourself to touch slugs and snails, you can sprinkle salt on them, which will dissolve them. Be aware, however, that dispensing too much salt on the soil can harm your plants.
The beer trick: That’s right, garden snails and slugs are notorious beer lovers. Actually, it’s the yeast that attracts them--but I prefer to believe the mollusks share distant Bavarian roots.
At any rate, the beer trick is a simple and surprisingly effective way to control the pests. Simply fill a saucer or other shallow container with beer, and place the vessel in your garden so that its rim is even with the soil. Slugs and snails will crawl into the bowl to imbibe. In the process of quaffing the suds, they drown. Simply dump out the deceased intruders in the morning, and refill the container.
In place of beer, a solution of sugar water and baker’s yeast can be used--one teaspoon of yeast per three ounces of water, with a pinch of sugar.
Traps: Traps are another effective, nontoxic method you can employ to cut down the snail population. Remember how snails need to seek shelter during the day? All you have to do is provide a few irresistible hiding places, then collect your victims for disposal at day’s end. Squashing a few of the intruders and leaving them under your “cover traps†will help attract new tenants the following night.
Lettuce and cabbage leaves, melon and grapefruit rinds, and scooped-out potatoes all make excellent traps. You can set a larger one by taking a wood plank or piece of plywood and elevating it about a half-inch off the ground.
Be aware that strategic placement is important in setting effective cover traps. Try to put yourself in a snail’s shell when placing one: would you pick this place to lay low after an evening of garden frolic?
Predators: Several natural predators like to feast on snails and slugs. Certain types of beetles, birds and lizards; salamanders; opossums and garter snakes will all chow down on the protein-rich pests.
There are also a few effective predators you can obtain expressly for the task. Two of the best are ducks and box turtles, which will eagerly devour snails and slugs. Trouble is, they may also devour other things in your garden.
Not so a third predator, which ironically enough, is another species of snail. Called the decollate snail, this is one relative you don’t want around if you’re a garden mollusk. About the same size as garden snails, but sporting longer, curlier shells, decollate snails feed almost exclusively on their cousins--and they leave most plants alone. They’re sold only in certain Southern California counties, however. Check with local nurseries on their availability.
Barriers and irritants: A final method of nontoxic snail control is fortification. The idea is to make it difficult for the intruders to reach your garden delicacies by putting unpleasant obstacles in their way.
Lay down crushed eggshells, gravel, wood ashes or bark (cedar and oak work best) around garden plants and flowers. The rough, sharp edges of such barriers will repel snails and slugs by irritating their soft bottoms.
Some gardeners have found that a seaweed mulch will repel snails just as effectively. Citrus growers have long relied on a more high-tech barrier: copper bands wrapped around the tree trunks. Snails and slugs will not cross the strips, which apparently leave a bad taste in their mouths.
One enterprising gardener in my neighborhood took the barrier approach to the extreme. After using other methods to extinguish his snail population, he embedded a ring of 1-by-8-inch boards in the ground, completely surrounding the garden. He then coated the undersides of the boards, which faced out at a 45-degree angle, with petroleum jelly. As a final measure, he sprinkled rock salt around the barrier’s outer edge.
A bit extreme, perhaps, but the wall was highly effective for a time. He even gave his barrier a name: “The Escargot Line.â€
