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written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

In 1980 I was new to cental Washington. I believed those who told me that the local climate was too dry for us to be bothered much by garden slugs. With less than a foot of rain a year, I believed them. It just didn’t seem wet enough. Imagine my surprise when I walked out in my backyard and noted hundreds of gigantic slugs on the back of the neighbor’s garage. I had never seen slugs this big before! I measured one and it was eight inches long!

The size was alarming and the vast numbers of slugs was troublesome. These slippery, mucousy molluscs would creep along our back deck at night, leaving a slippery slime trail and deterring anyone from going out barefoot. Imagine stepping on one of these giant slugs in the dark. Ugh! Fortunately, these slimy critters seemed to prefer noshing on the shrub undergrowth, instead of devouring my garden. Because there were so many slugs, we periodically put out slug bait, but it was a losing battle because of their overwhelming numbers. Thankfully, when we moved to a new house, it didn’t have slugs.

Slugs haven’t disappeared from area gardens, but area gardeners seem better equipped to fight them. There are two main types of slug fighting molluscicides (pesticides that kill slugs). One material, metaldehyde, has been available since the 1930s. It can be found in granules, sprays, and bait products available for killing slugs. Familiar products containing metaldehyde include Deadline, Go-West Meal, Slug-Tox, and Cory’s Slug and Snail Death. The problem with these products is that they can also be toxic to wildlife such as our dogs, other pets, and birds. They must be applied correctly to help prevent unintended poisoning of animals.

Other slug-fighting materials contain iron phosphate, a comparatively non-toxic chemical that can be used safely in the garden without worrying about children and pets. Iron phosphate molluscicides first hit the market in the United States around 1997. Materials such as Sluggo, Escar-go, Slug Magic, and Worry Free baits are now readily available to gardeners. Glenn Fisher, Oregon State University entomologist, has researched the effectiveness of different slug baits and found that the iron phosphate baits are just as effective as the metaldehyde baits.

If you have a slug problem and are intending to fight the problem with slug fighting pesticides, Fisher points out the following:

– You will never get rid of all your slugs since “90 per cent of the slugs are underground at any one time.” The best anyone can expect is to decrease the population by 60 percent.

– Apply baits in the spring just before new growth emerges and before little sprouts pop out of the ground. Slugs are more likely to go for the bait before tender new food becomes available.

– Cereal-based baits performed the best for Fisher, especially in areas exposed to frequent rain or irrigation. Fisher found that the baits were most effective when applied right after irrigation or rain when conditions in the garden were moist. That’s when the slugs are most likely to come out and give them a try. Be sure to follow label directions and keep in mind that slugs are nocturnal creatures.

– Apply baits twice in the fall. When weather starts to turn cooler in the fall, apply a slug bait to kill slugs before they lay eggs, and again a bit later in the fall to kill the baby slugs that slipped by the first application of bait.

Trapping is another method of slug “control” that seems to appeal to gardeners, perhaps it’s because beer is often used to bait these traps. The slugs are attracted to the traps by the odor of the beer and then fall into the trap and drown. While beer-baited homemade and commercial slug traps are one way of decreasing slug numbers, they usually aren’t effective in decreasing large slug populations in large garden areas. That’s because the beer-baited traps attract slugs only within an area of a few feet. Slug traps are also labor intensive, needing to be cleaned out and refilled every few days.

By the way, there is no reason to waste good beer or ale on your garden slugs. The slugs are not beer connoisseurs, they’re simple attracted to the odor of fermented sugar. You can make a mixture of one tablespoon of yeast, one tablespoon of flour, one tablespoon of sugar, and one cup water. It will ferment and attract the slugs just like beer does.

It might be more fun to go out into the garden every night after dark and use a flashlight to locate these slimy creatures. You can kill them by dropping them into a bucket of soapy water. You may be able to enlist the help of other family members by having a contest to see who can collect the most slugs and provide special rewards for the largest and smallest slugs found. If you’re good at it, you may even make a dent in the slug population. Have fun slugging it out!

Published: 7/19/2008 1:48 PM



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