Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
July, 2008
Regional Report

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Mushrooms are a favorite food of banana slugs, which live on the forest floors along the Pacific Coast of North America.

Slimy Slugs, Slippery Snails

Whenever I spot a trail of glistening slime leading across a leaf or flower, I know that a slug or snail has been feasting. I'm always amazed at the amount of damage they can do in a relatively short period of time.

Slugs and snails are mollusks, more closely related to scallops and clams than insects. They range in color from greenish yellow to brown, black, white, charcoal gray, or rosy pink. Snails carry protective shells on their backs, retreating into them whenever they feel endangered. Most slugs are naked snails with no visible shells.

Controlling the Pests
The simplest way to control the amount of slugs and snails in your garden is to create an environment they don't like. Eliminating their favorite hiding places, such as piles of wet leaves, is a good first step. To catch them in action, start night patrols. They're easy to find during the evening or early morning hours when they're feeding the most. Handpick and destroy any critters you find. During the day they hide, often under flowerpots or plant debris. Moving these items around will often uncover a whole community, ripe for the picking.

Keeping Them Out
You can deter slugs and snails by placing barriers in their paths, from fence-like metal enclosures to materials sprinkled on the ground around the plants you want to protect. Solid copper strips make the best barrier, giving the mollusks an electric shock when they come in contact with it. Use at least a 3-inch-wide strip and lay it along the edge of beds, wrap it around tree trunks or pots, or stand it upright like a fence. Be sure to check for slugs and snails caught inside the barrier.

Laying paths of organic substances, such as wood ash, shredded bark, sand, or diatomaceous earth, around plants also will deter most slugs and snails. They don't like crawling over these sharp materials.

If handpicking and barriers don't offer adequate control, you can try trapping the critters. Successful traps require some form of attractant. The most widely known trap is beer. A Colorado State University study discovered that slugs and snails seem to prefer Kingsbury Malt Beverage (nonalcoholic), Michelob, Budweiser, Bud Light, and Old Milwaukee, in that order.

Raw potato slices, lettuce, yeast, smashed slugs, or commercially prepared wheat-based products also work well as attractants. Baits containing iron phosphate (such as Sluggo or Escar-Go) are safer for children and pets than baits containing metaldehyde, but it's still important to keep this and all other pesticides out of the reach of children and pets. I place the lure of choice on a plastic saucer and prop an aluminum pie pan up a few inches above the saucer to protect the bait from rain, pets, and curious children. I empty the trap every morning and replace the bait as needed.

Natural Predators
Fortunately there are a number of beneficial creatures, such as toads, frogs, snakes, ground beetles, and predatory snails, that love to eat slugs and snails. Even ducks, geese, and chickens can be sent on patrol to reduce slug and snail populations. You can encourage these beneficials by providing a diverse habitat in and around your garden and reducing your use of pesticides.

I use a combination of these methods to control destructive slugs and snails in my garden. I haven't gotten the upper hand yet, but it is certainly not from lack of trying! With that said, here's a disclaimer: Not all slugs are enemies and I'd be remiss if I didn't mention our native slugs, which are considered beneficial. Here in the Pacific Northwest we have Ariolimax, the second largest species of slug in the world. Called the banana slug because of its yellow color, it can grow to nearly 10 inches in length and weigh in at a quarter of a pound.

Banana slugs live on the forest floor where they process leaves, animal droppings, and dead plant material and recycle them into soil. If you garden near a forested area and happen to find one of these native recyclers in the garden, do him and yourself a favor by picking him up and tossing him back into the forest where he can work his magic on the forest floor.

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