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Slug Wars: Slug Control for Organic Gardens

Acrobatic slug munching on a Stargazer lily bud.

Super slug acrobat munching a Stargazer lily bud.

After my success with the potato bugs, I was feeling quite cocky. Until today. I have just come in from my garden where I noticed those shiny, slimy tell-tale slug trails in my veggies and a number of cucumber leaves with large slug-munch holes. Gah!

I live in the slug capital of the world. Well, at least it feels that way. We do see an occasional snail, but for the most part, it is those long, brown European red slugs, Arion rufus. In my area, they are rusty brown to really dark brown, and some are probably the black slug Arion ater, but without dissecting the things to check out the reproductive anatomy, there is no way to tell.

Frankly, makes no difference what their names are, and the closest I will ever come to dissecting a slug is cutting one in-half with my garden trowel. There are other species of slugs here, but these are the ones I find in my garden. Now for a little slug-fo ("slug" and "info". Clever, eh? I’m like that, you know).

'Slug-Fo' 101

Slugs belong to the large class of gastropods, from the Latin gastro (stomach) and pod (foot), and they do in fact serve a purpose by literally eating their way through life. Makes sense if you are basically just a stomach traveling around on a slimy foot — and eat they do!

These slime-coated denizens of my garden are not particularly picky eaters, which makes them useful in the environment — just not my garden. By breaking down dead organic matter, including animal feces, nitrogen, and other essential nutrients, get recycled and reused in different ways. I hate to admit it, even by fertilizing the soil.

Also, believe it or not, slugs are a part of some animal diets. Birds, like geese, ducks, chickens, blackbirds, and thrushes, as well as frogs and toads, are a few of the slug connoisseurs in our world.

Slugs reproduce by finding a mate or through self-fertilization since they are hermaphrodites. My local European slugs can lay up to an unsettling 500 eggs a year! If only they would stick to dead stuff and the dog poop. I have yet to be successful with slug training or relocation efforts, and thus my garden continues to be a slug battle zone.

Radish casualties.  

Slugs love my radishes.

Slug Anatomy for Dummies

If you look at the acrobat on my oriental lily (top photo), you can clearly see a large hole called the "pneumostome," or breathing hole. This is situated in the slug’s mantle, a vestigial anatomical area that, if he/she were a snail, the shell would be secreted from here. This is also where the slug sucks its head into for protection.

Under the mantle is the slug’s anus and genital openings. You can see a faint line running under and sort of parallel to the hole and this is the bottom margin of the mantle. The long, light-brown line running somewhat the length of my now-deceased circus slug is its skirt. Above the skirt is the foot and below the skirt is naturally the sole in goofy slug anatomy.

The two long tentacles on the amazing Sluggo’s head are light-sensitive opticals with the shorter tentacles underneath that area being sensory for tasting and feeling. I am so thankful my taste buds are not on my fingertips. They also smell through their eyes (optical tentacles).

Here is the disturbing part: Slugs have mouths full of teeth! Literally rows of thousands of rear-facing replaceable teeth that they use not only for eating my radishes but also fighting each other. If you are a banana slug, those teeth can make for some pretty perilous sex. It is a bit X-rated, so I won’t go into details, but it sounds like it is all fun and games until one slug chews off the other’s, ahem, appendage. Enough of the slug parts.

 Slime trail.

A petunia's leaves with slug slime.

Sluggomotion: Slip-Sliming Away

How does a slug get around my garden? Up a 3-foot lily? It’s all about the foot, ‘bout the foot, ‘bout the foot, and mucous. More than one type of mucous at that.

The slug’s slime is a multi-purpose mucous that keeps the gastropod from drying up into little slug raisins (muffin anyone?), leaves a trail for future mates to find them by (imagine if this were true for humans), provides self-defense, and lubricates their way around the world. Not all slug slime is created equal, though. After all, a slug cannot live by thin slime alone – one must have thick slime for traction (like climbing up lily stalks).

Then there is that muscular foot. Through a series of complicated muscle movements, the amazing Sluggo and his/her acrobatic buddies slide around, up and down, and all around, wagging their slug trails behind them. Propulsion created through waves of muscular motions and some slimy-goo for those hard-to-reach spots.

 Can o' beer trap success!

Successful can o'beer trap!

Time for the Punch Line: How to Control Slugs

I use several different prongs of attack in my war against slugs. There are other safe methods — these are my favorites and have worked the best for me and my garden.

Encourage natural predators to visit. Create habitats for toads and frogs and feeding stations to attract a variety of birds.

Frequently monitor for damage. This is very important to baiting and slaying. Know your enemy! Slugs do most of their feeding at night. During the day, they hide in cool, moist spots such as under flower pots (being squishy has it perks), rocks, wood, debris, and similar. Search and destroy missions should be targeted at these areas.

I have also found walking around after a light rain is helpful, since this brings them out of hiding. One spring evening, just about dusk, I went walking around my yard and those brown buggers were everywhere! I quickly donned some most stylish vinyl gloves and started “picking.” I filled a gallon bag. No joke. It was a triumphant, albeit gross, moment.

Beer traps are a favorite but require thoughtful placement. I use two types: cat food cans sunk into the ground and glass jars on their sides. The cans should not be flush with the ground – this prevents beneficials from accidentally stumbling in. The horizontal jar is slightly angled to help the beer pool at the bottom and keeps most of the rain or sprinkler water from filling the trap up. I do not empty them every day unless the trap has filled with slugs.

There are also commercially made traps. These are more eye-appealing, if that is a concern. These guys are not beer snobs. Cheap is fine. I had a homebrew batch that didn’t turn out well and use it and the slugs are loving it to death!

Using slug bait. I was using a purportedly safe slug bait and killer product that contains iron phosphate. However, the more I read about it, the more skeptical I am. Even though it was approved by the Organic Materials Review Institute (OMRI), I don’t think we know enough. Remember, there was a time in the not-so-remote past that people thought glyphosate was safe.

By the way, the next time you get slimed, wipe it off before washing. That mucous is hydrophilic, meaning it loves water and will become more instead of less. What are your tried and true safe slug slaying methods?

Susan Slape-Hoysagk is a registered nurse who moved her family to the northern Oregon coast in order to live a more self-reliant life. She gardens and cans and enjoys backpacking, hiking, camping, skiing and swimming in the nearby lake. Connect with Susan on her Dreaming in a Sleepless World Blog and on Facebook. Read all of Susan’s MOTHER EARTH NEWS posts here.

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8/14/2016 1:24:39 PM

Hi Jura and Anonymouse - thank you for sharing your experiences! Good to know about the Dominique hens and the nettle slurry. People keep telling me "just put salt on them." Besides the gooey mess this leaves behind, salt is not good for your plants. Especially in the amount I would have to use!

8/12/2016 9:01:50 PM

Large Fowl Dominique hens are excellent for slug and snail control. Our Black Star hen used to puff her feathers in disgust when she followed the Dominique ladies food calls and found that they were eating *slimy* things. The Dominiques even went under the deck to pick slugs and snails from the underside. We had our backyard, up to and including our trees, overrun with slugs and snails. After having the Dominiques out for about four hours a day for two or three weeks I went out one evening and realized that there were NO slugs on the deck, in the trees, or anywhere else I looked.

8/12/2016 4:07:59 AM

Thanks for sharing your knowledge. A few words from my observation: Neighboring ducks and geese avoided eating slugs unless faced starvation. 2 years ago we had invasion of the barbarian slimy tribe, what made me to find out ways to combat it. Beer traps and manual collecting after evening rains- #1 way of ad hock decreasing their number. Copper wire coiled around mushroom stumps and raised bed edges curbed with copper strip stood for a #1 mean of preventing them from foraging on my crops. It worked until the copper got oxidized and as such stood as no hindrance to the beasts. (treating with an abrasive paper helped) Coarse material (shattered glass ) placed on their pathways did not work at all btw. Firstly I used to put my mucous harvest into a jar with a salt (which produced a waste product of no future use), but then stared to think in a permaculture way and dumped the collected slugs into nettle slurry (or high temp compost pile).

8/11/2016 11:39:59 PM

Hello Martha and thank you for taking time to comment. I have heard of people using copper wire and strips for slugs, thank you for sharing. I have not had problems with my potted plants but will keep this in mind for future use. Thanks! Susan

7/28/2016 7:11:58 AM

Finding damage to houseplants that spent the summer outside, I realized snails and slugs were responsible. I tried using copper tape and also wrapping pots with copper wire seems to work. I read that copper gives the pests a "shock." Though I have not witnessed it happening, this summer there were a few wandering snails & slugs in the morning. I believe the copper works in preventing them from getting into the planters.

7/23/2016 5:07:55 PM

Hi Amanda! It has taken me some years to get things under control. Late summer into fall is when they lay their eggs. Some hatch and some over-winter to hatch early next spring (also a good time to really hit them. I never get rid of all of them but I have cut their numbers down significantly. Look up slug eggs online,especially the pictures. Finding and destroying them are very helpful in decreasing their numbers. Food grade Diatomaceous Earth (DE)is something that works well in dry conditions. It isn't an instant kill but is another method of attack. Just keep trying and thanks for reading my blog and stopping in to comment!

7/22/2016 2:44:41 PM

Hi Susan, slugs are my nemesis too! Every year they plague me, and it seems that no matter what I do, I can never get rid of them all. I have tried beer traps but that didn't seem to work well for me. Salt works if you can pour a bit right on them, or I have had success with a diluted ammonia spray. This year I resorted to using slug bait (iron phosphate) because I just didn't know what else to do-here in Calgary in June and July the days are so long that I would have to be outside at 2 am in order to pick them off the plants at night. I do go out first thing in the morning, and as you said, after a rain there seems to be more of them out there and I pick of quite a few. Mine are small brown ones here, harder to find, but just as voracious! I picked quite a few off of my rhubarb this morning!