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How to Kill Slugs

Review of a Funny, Useful Book

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Picture of Minute Man hosta. As the photo shows, Minute Man hosta has variegated leaves.

Hosta is one plant you'll want to protect from these voracious garden pests.

David Beaulieu

50 Ways to Kill a Slug by Sarah Ford is packed with control tips for outwitting "the garden's number one enemy." It is first and foremost an informative, inexpensive little book that will help you overcome a major pest that ruins millions of landscape plants every year. Secondarily, because it is also written in a manner designed to bring a smile to your face, it could be a great way to get your kids interested in gardening. And who knows, maybe they'll even help out a little?

In my book review below I reveal some of Ford's secrets, focusing on the more-or-less organic ways to kill slugs.

Studying Up on the Enemy: Facts You Can Use in Killing Slugs

Before listing some facts cited in this book that you can use to help you kill slugs, let me report some information provided by the author that may motivate you (even more than you already are) to wage war on these garden pests:

  1. Slugs (Arion lusitanicus) are hermaphroditic, meaning they can mate with themselves
  2. "A slug has a lifespan of several years" (2-6)

When you combine 1 and 2, it helps account for why there are so many of them -- and why it's so necessary to have a plan to kill slugs, assuming you value your plants.

The following facts about slugs cited by Ford will be especially helpful in this pest-control project:

  1. They hide in dark, wet spots during the day and do their munching at night
  2. They exhibit a fatal attraction toward, for example, grapefruit rind and -- most famously -- beer
  3. In contrast, some other food-related items repel them, including salt and vinegar
  4. They dislike crawling over sharp objects with their soft bodies
  5. Despite their sliminess, they do have some natural predators

Before launching into the various ways to kill slugs, Ford wraps up the book's introduction by pointing out that one of the best preventive steps you can take in your battle is to engage in spring cleaning outdoors every year and, generally, to keep your landscape tidy, since slugs need something under which to hide out during the daytime. Also, since many people wonder, "After I kill slugs, what do I do with the bodies?" Ford notes that it's fine just to put them in the compost bin.

Barriers

Picture of foxglove flowers. Foxgloves are poisonous plants.

Picture: in contrast to hosta, slugs hate foxglove plants.

David Beaulieu

Ford covers three kinds of barriers that are effective in repelling slugs:

  1. Things that smell bad to slugs
  2. Sharp stuff that cuts into their soft bodies
  3. Materials that dry out the slug's moisture-craving skin on contact

Included in the first category, according to Ford, is the foxglove plant, which you can grow around plants that slugs eat to form a living barrier. Meanwhile, the second group includes:

  1. Diatomaceous earth
  2. Eggshells
  3. Grit
  4. Sand
  5. Gravel
  6. Crushed nuts
  7. Seashells
  8. Pine needles
  9. Sawdust
  10. Hair (both human and animal)

An example of the third type of barrier is the soot you scrape from your chimney.

Yucca extract, vinegar and salt are other products that are anathema to slugs. Elsewhere, I have discussed vinegar as a natural weed killer. Both vinegar and, especially, salt must be used in moderation, as they can have deleterious effects upon your garden when used in excess. Personally, with so many ways available to kill slugs, I'd avoid any tactic with possible negative consequences (why chance it?).

Traps to Kill Slugs

As I detail on Page 2 of my article on hosta plants, the beer trap is a classic way to kill slugs. The varmints will crawl into a beer-filled container (sink it into the ground) and drown. Hostas are one of the plants most often damaged by this pest. Delphiniums have the dubious distinction of also ranking high on the list.

Another example of a trap suggested by Ford is grapefruit rind. How do you make such a trap? Just buy a grapefruit, cut it in half, and eat the good part. Then take what's left over from these two halves (primarily the rind) and, using a knife, make a small notch on the edge of each (big enough for a slug to crawl through). Place them down on the ground (edge down), such that they form little domes.

The idea is that slugs will be drawn to the grapefruit halves. They will use the "door" (i.e., the notch you cut) in each to crawl underneath, where they'll spend the night. Then, in the morning, you'll:

  1. Check traps
  2. Find victims
  3. Kill slugs
  4. Repeat

On display here, by the way, is just one of many examples of Ford's sense of humor. Instead of using a boring title like "Grapefruit Trap" for this section, Ford's title is "Create a Slug Playhouse." And there's a drawing showing cartoonish slugs residing in igloo-like structures, replete with curtains, doors, chimneys, etc. Children will love it -- perhaps enough to help you out by going outside and setting up such slug traps.

Incidentally, Ford is British, but for the most part she avoids Britishisms. However, there is one example in this chapter. In speaking of using old carpet as a slug trap, she writes, "The next time you are taking a worn-out carpet to the tip, save a few small pieces to make a slug trap." "Tip" is a Britishism for "dump."

I, myself use old lumber for slug traps. But whether it be carpet, boards, or whatever, the principle is the same. The slugs, seeking darkness and moisture, will congregate underneath; you later check the trap, kill slugs, and repeat.

Baits, Plants Not on the Menu, and Predators That Kill Slugs

Picture of peony flower. As this peony flower photo shows, some of these perennials are burgundy.

Slugs seem to leave peonies alone, for the most part.

David Beaulieu

Let me conclude by mentioning a few of the many other options covered by the author.

If you scatter oat bran on the ground as bait, slugs will eat it. Then something funny happens: the oat bran expands while inside their bodies, and they will explode! Again, your kids will probably be dying to try this method out once they read about it.

Cat food and dog food are also good baits according to Ford. These pet foods won't kill slugs, though; you have to finish them off yourself, after the critters unwittingly take the bait. Ford admits there's a problem with the use of this bait, however: it could also draw stray cats and dogs. Not to worry, I have your back. Just consult the following two articles to address these problems, should they arise:

Some plants simply don't end up on the typical slug menu very often. So you could grow just these plants if you really wanted to take the easy way out. In this category Ford lists, for example:

Finally, if you want someone else to do your dirty work for you, the following are listed by Ford as being predators that will kill slugs:

  • Birds (thrushes, specifically)
  • Frogs
  • Toads
  • Salamanders (but they would have to be large salamanders)
  • Moles

If you're already laboring over the separate issue of mole control, however, you're unlikely to take much consolation in the fact that moles kill slugs.

50 Ways to Kill a Slug was copyrighted in 2003 by Octopus Publishing Group Ltd.

Disclosure: A review copy was provided by the publisher. For more information, please see our Ethics Policy.

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