Community Horticulture Fact Sheet # 92 Slugs Few Northwest Gardeners
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Community Horticulture Fact Sheet # 92 Slugs Few Northwest gardeners have escaped the fleshy lobe just behind the head. They reach 5 damage done by those gluttonous garden to 6 inches, but when resting or under attack, inhabitants, slugs. They can quickly devour European black slugs curl into a ball. newly planted marigolds and lettuce. Ideal living conditions make Western Washington a •Great Gray Garden Slug - Limax maximus. veritable slug paradise. Our wet climate Native to Europe and Asia Minor, gray garden provides slugs with the moisture they need to slugs have a spotted or striped mantle. They survive and an abundance of plants to eat. are about 4 inches long, but can move four Combine this with the slug’s ability to times faster than a banana slug. These reproduce in large numbers, and it’s a wonder cannibalistic slugs are a serious threat to the we aren’t ankle deep in slug slime! native banana slugs. Slugs are soft-bodied animals without a •Milky Slug - Deroceras reticulatum. Imported backbone. Their heads contain a from northern Europe and Asia, milky slugs get concentration of nerve cells and sport tentacles their name from the milky slime they produce, tipped by small, light-sensitive eyes. Slugs especially when irritated. About 2 inches long, move on a muscular foot over a mucous trail they are usually light brown or gray with darker (slime) which is secreted by a gland beneath mottling. The concentric folds on the mantle the head. They can live from one to six years and a ridge running down the back help identify and can lay 500 eggs per year. They are milky slugs. They are a major pest, primarily herbivorous, avidly consuming green responsible for damage to grain fields, plants as well as fungi, lichens, worms, strawberries and vegetable crops. centipedes, insects, animal feces and carrion. •Greenhouse Slug - Milax gagates. Introduced Common Slugs found in this area: from the Mediterranean area, greenhouse •Banana Slug - Ariolimax columbianus, A. slugs are gray and 2 to 3 inches long with a dolichophallus, and A. Californicus. Their size, sharp ridge running along the back from mantle color and preference for wooded areas easily to tail. They prefer living in greenhouses, identify the only slugs native to the Northwest, burrowing into the soil and eating the roots of banana slugs. Up to 8 inches long, they are greenhouse plants. the second largest slugs in the world. Banana slugs can be white, yellow, tan, or brown and Slug Control: they usually have black spots. They prefer to Slugs play an important role in the complex feed in forests, but, if humans build within their interrelationships of the natural world, so habitat, they may continue to feed in gardens. elimination of all slugs would be both unwise and unjustifiable. We must maintain our •European Black Slug - Arion ater. Not always gardens by keeping destructive slug black, these slugs can be identified by the populations down in an environmentally ridges and furrows behind their mantle, the responsible manner. Try these suggestions: 600 128th Street SE, Everett, WA 98208-6353 425-338-2400 • Fax: 425-338-3994 • Master Gardeners: 425-357-6010 • TDD 1 -800-833-6388 • http://snohomish.wsu.edu • http://gardening.wsu.edu Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, sex, religion, age, color, creed, national or ethnic origin; physical, mental or sensory disability; marital status, sexual orientation, or status as a Vietnam-era or disabled veteran. Evidence of noncompliance may be reported through your local Extension office. Change the environment: Commercial slug baits: 1. Make your garden less alluring to slugs As with any pesticide, use slug bait by growing plants that slugs ignore and responsibly. Read the entire label and follow avoiding plants that slugs like. all directions carefully. 2. Plant a “sacrificial garden” full of plants that slugs love and eliminate the slugs you Until recently, most commercial slug baits were attract to it. a combination of a bait ingredient like apple 3. Start keeping slug-eating ducks, geese meal or bran and the molluscicide, or chickens, realizing that they may prove metaldehyde. Such products must include the equally damaging to your garden. following statement on the label: “This Encourage natural slug predators, such as pesticide may be fatal to dogs or other pets garter snakes, birds, frogs and ground if eaten. Keep pets out of treated areas.” beetles. Although you can apply it to the soil around 4. Eliminate places for slugs to hide: low- plants (being careful not to contaminate the branched shrubs; ivy or other ground edible parts of plants), it is best to put it into a covers; stacked wood; rock piles; tall grass slug trap. (See above.) and weeds; and piles of leaves. 5. Do not overwater. Remember that slugs If ingested by humans, metaldehyde can cause need moisture to survive. serious (even lethal) damage. Birds and other 6. Cultivate garden soil frequently to wildlife, especially small mammals, may die destroy slug eggs before they hatch. from feeding in metaldehyde areas. 7. Garden in wood-framed beds surrounded with 3-inch wide solid copper New slug baits are now on the market that are bands. When they touch the copper, slugs considerably safer for you, your pets and the receive an electrical shock. Copper environment. Under such brand names as banding is expensive, but it is also effective Sluggo, Worryfree and Escargo, they contain and permanent. Copper foils are much less iron phosphate as the active ingredient. These expensive, but will need replacing every baits work best if slightly moist, so apply them year or two. directly to the soil. They break down into 8. Have a slug hunt. Pay children to catch elements that act as a fertilizer in your soil. slugs or arm yourself with a flashlight and venture into the garden at night to pick Plants Slugs Plants Slugs slugs off plants. Drop them into a jar of Love Do Not Like soapy water. Gentians Anemone 9. Make slug traps. In the sides of a Lettuce Baby’s Tears plastic margarine tub, cut several one-inch- Lilies Bamboo square holes near the top. Put in bait, snap Lobelia Bleeding heart on the lid and put a rock on top, so it Marigolds Coral bells doesn’t tip over. Alternatively, make a trap Narcissus Cyclamen using a 2-liter pop bottle. Remove the cap Primroses Evergreen candytuft and cut the top off the bottle at the Strawberries Foxglove shoulder. Put the cut piece into the bottle Trillium Impatiens with the neck pointing in and duct tape the Tuberous begonias Sedum two parts together. Violas Wax begonias 10. Bait either trap with beer, a mixture of 2 Tbsp. flour, ½ tsp. brewer’s yeast and 1 tsp. Sources: The Western Society of sugar dissolved in 2 cups warm water, or Malacologists Field Guide to the Slug by commercial bait. When full, dump the trap David George Gordon in the garbage and make a new one. The Banana Slug by Alice Bryant Harper • Prepared by Betsy Koepp, WSUMG (96) and Kennell 8/03 .