Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
July, 2010
Regional Report

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Banana slugs live on the floors of forests along the Pacific Coast of North America. They seem to have a fondness for mushrooms, and they spread seeds and spores when they eat.

Creatures of the Night

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, a place to retreat when they feel threatened. Most slugs are naked snails with no visible shells.

Controlling the Pests
The simplest way to control the number of slugs and snails in your garden is to create an environment they don't like. Eliminating their favorite hiding places, including moist garden debris and piles of wet leaves, is a good first step. To catch them in action, go on garden patrols after dusk. They're easiest to find in the evening or early morning hours when they're most actively feeding. Just handpick and destroy any critters you find. During the day they hide and you'll often find them under flowerpots or plant debris. Move these items around and you'll 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 good barriers, giving the critters an electric shock when they crawl over the strips. 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.

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

If handpicking and barriers don't offer control, you can try trapping the critters. Successful traps require some form of attractant to lure them to the area. The most widely known trap is baited with beer. A Colorado State University study discovered that the critters' favorite beers are 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 to use than baits containing metaldehyde, but it's still important to keep these and all other pesticides out of the reach of children and pets. I've also had success trapping slugs and snails by soaking a terra cotta pot in water and then up-ending it in the garden, using a stick or stone to prop up one side. The slugs crawl in to hide and each morning I empty the trap and reset it.

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. You can encourage these beneficials by providing a diverse habitat in and around your garden, and by 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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