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Electric Snail Fence: Organic-Tec

Electric snail fence overview:

In the past, I had been unsuccessfully fighting the battle against snails and slugs.  However, I recently discovered a very effective and relatively cheap organic way to fend off those pesky gastropods. The solution is simply to surround the tender greens with a battery-powered snail fence. This article will go through the details on how an electric snail fence works and the simple materials I used to make it happen.

 

Disclaimer:

I hate that I have to add this disclaimer.  However, since someone could possibly get harmed doing just about anything, I feel that I have to add this in.  

This electric snail fence is just something that I did for myself and I am only sharing my success story.  I am not telling anyone to go out and create this simple and very effective snail barrier.

 

Simple circuit:

  • Since the electric snail fence that I created is basically a modified simple circuit, I am going to take a few moments to go over some of the basics of a simple battery-powered circuit.
  • If you look at the first diagram (figure 1), you’ll see that there is a cartoon of a 9 V battery with a black wire and a red wire coming out of it. In this diagram, the red wire is also connected to a light bulb in series. Because the red wire and the black wire are not touching each other, the circuit is incomplete and no electricity is flowing through the system. Note the ubiquitous snail in this cartoon is relatively unimpressed by the current state of affairs.
simple circuit

(figure 1) simple circuit

 

  • In the second cartoon (figure 2), the ends of the red and black wires have been connected which completes the circuit. As a result, electricity is now flowing through the system and the light bulb is shining. The snail in this image is only minimally more interested than it was in the previous figure.

 

 simple circuit with light

(figure 2) simple circuit

 

Basic background information:

  • However, what the snail does not realize is that he is an excellent conductor of electricity. In the third cartoon (figure 3) you can see that the unconcerned snail has continued to crawl forward. By touching just one exposed wire, the circuit is incomplete and the snail continues to be unenlightened.
snail tempting the simple circuit

(figure 3) snail tempting the simple circuit

 

  • In the fourth cartoon, (figure 4), the snail has inched forward just enough to touch both bare wires at the same time. Since the soft parts of a snail are a great conductor of electricity, the snail has completed the circuit. Electricity is now flowing through the system and the snail is… well… shocked.
(figure 4) snail shocked

(figure 4) snail shocked

 

  • Unfortunately, the system presented so far only works if the snail is in that one strategic spot where the wires meet. Considering that the snail can crawl around the wires, there needs to be a more complete way to utilize this system and protect tender young plants.

 

(figure 5) snail on the loose

(figure 5) snail on the loose

 

Snail fence diagram:

  • As we now know, encircling seedlings with just one wire (figure 6), will do nothing to protect plants. The snail in this case can easily crawl across the uninsulated wire without any concern of completing the circuit and getting shocked.
(figure 6) snail unbothered by the one wire

(figure 6) snail unbothered by the single wire

 

  • However, if the seedlings are encircled with two complete parallel wires from each side of the battery, then there will be an effective barrier. In the next cartoon (figure 7), we can see each parallel wire is connected to its own side of the battery.
Electric Snail Fence

(figure 7) snail beware

 

  • It is also important to note that the wires from each side of the battery must not touch each other for the system to work. If the wires do touch, that will complete the circuit and electricity will take the path of least resistance to complete the circuit. In addition, touching wires will drain the battery. As you can see in the diagram, the red wire arches over the black wire in the top left side of the circle.  This arch allows complete circumferential protection of plants while also keeping the uninsulated wires from touching each other.

 

  • Finally, in search of a tasty morsel, the snail has inched forward (figure 8).  In doing so it has put itself in a position where it has touched both wires at the same time. The snail being the good conductor that it is, has completed the circuit and will likely find the experience rather unpleasant.
Electric Snail Fence

(figure 8) poor snail doesn’t get to snack

 

I am working on a video that I will soon upload to show the system in action (stay tuned).

As promised, I have created a video about all of this that is now viewable on YouTube (click on the image below)

 

 

Materials and Methods:

There are likely many ways to put this conceptual snail fence system into reality. However, the following are the materials and methods that I’ve used and found to be successful. The inexpensive materials that I have used can be found at any home improvement or hardware store.

 

What you need and how to put it together:

 

Wire:

The wire needs to be exposed/uninsulated wire for it to work.  Insulated wire will protect the snail from the electric exposure and will therefore defeat the whole purpose.  The wire that I have used to surround the plants is 18 gauge aluminum wire. I like the aluminum wire because it’s a good conductor of electricity, it’s relatively cheap and perhaps most importantly it won’t rust.  I suspect galvanized steel wire will work too, although I have not tried it.

Wire distance:

The parallel wires surrounding the plants need to be close enough together so that a snail can touch both ends of the same time. However, the wires should not be so close together that they will easily touch each other. I have used a distance of approximately 1 cm or 1/2 inch.

 

Securing the wire:

Stabilizing the wire is an important part of this system. Wires that aren’t secure will be prone to move and touch each other or migrate away from each other to the point of ineffectiveness.  Securing the wires to something solid also prevents snails from crawling under the wires.  I found it pretty easy to just staple the wires to the wood of a planter box.  An electric staple gun makes this a lot easier, but a hand powered staple gun will work too.

I stapled the wires to the top of the wood, but I suspect that stapling to the sides would be just as effective.  One drawback to stapling to wood is that when the wood becomes wet it is also a week conductor. Therefore, in chronically moist conditions, over time the battery could be drained of power.

 

Light bulb:

The light bulb is an optional part of the electric snail fence . However, I like having a light bulb in the circuit because it makes it easy to test the system. If the wires are touching, then the light will be on to inform there is a problem that needs to be adjusted.  In addition, touching the wires with a piece of metal at a later time is a convenient way to test the battery’s power.

 

Housing unit:

The battery (and optional light) need to be protected from water damageSmall food containers are a cheap and effective way to protect electronics from the elements. However, a small hole needs to be created in the side of the container for the wires. Unfortunately, this hole then becomes a weak link in the barrier against water. To address this issue, once the system has been put together, I apply a liberal amount of grease in and around the hole which I found to be very effective.

Battery:

I like using a 9 volt battery because it provides good amount of voltage to do the job, but not over do it.  In addition, battery clips for a 9 volt battery are small and cheap.

 

Inside, outside, leave me alone:

It is possible that there will be snails inside the flower box after protective electronic barrier is established.  Therefore, it is very possible that this electric snail fence would not only keep snails out, but also trap snails in.  Handpicking the snails out of the protected area is necessary.  In keeping with the organic theme, snail beer traps within the barrier may help to address any remaining stragglers trapped within.

 

Warning:

  • Bad things can always happen.
  • For example, if a battery gets wet or becomes old it can corrode and leach battery acid. Battery acid can eat through plastic and therefore go into the soil or harm anything else for that matter. Battery acid can also burn skin.  I have not had any of these issues but I know they could potentially happen.  So please be careful anytime you use batteries.
  • In addition, anytime electricity is used, there is always a conceivable risk that somehow, under the right circumstances, that it could start a fire.
  • As a result of these potential hazards, (and others that I haven’t yet thought of), I am only presenting this information as a story of what I have done.  I am not recommending that anyone go out and create this simple, cheap, effective and organic system for protecting plants from snails and slugs.

 

An easier option?

After I figured all of this out and felt pretty good about myself… I then discovered that you can just buy a product that is basically plug and play.  It is called  “SlugsAway Electronic Slug And Snail Fence” and quite honestly it looks a lot easier to set up.   That being said, if you are covering a lot of ground, it would be cheaper to use the snail fence described in this post.

Good luck and happy snail free gardening!

 

 

About Thomas Osborne, MD

Dr. Osborne is a Harvard trained Radiologist and Neuroradiologist who loves to share his insight about medicine and gardening.

9 comments

  1. Okay, this looks really impressive but I know me. I will probably curl my own hair before I zap a snail. So I go the easy route; I use diatomaceous earth. It’s a bit cruel as it tears their soft underbellies up but, like you, I want to enjoy my own lettuce.

    • Thomas Osborne, MD

      Thanks Pat!
      The electric snail fence does work surprisingly well. I also do my best not to harm other living things… but there’s a point where I will not eat anything from my garden if I just watch in pain as my plants are devoured.

      On that note, more often than not, the snails only get a small zap a few times before they turn back. Ill upload a video to youtube (and add it to the site) soon that shows this. However, on occasion a snail does get stuck and, well, cooks. Sigh.

      I have not heard about your diatomaceous earth technique. Sounds interesting. Perhaps you could share some more information about his when you have a chance. Thanks!

  2. Hi I am interested in the electric snail/slug fence and I am wondering if copper wire could be used instead of galvanised or aluminium?

    • Thomas Osborne, MD

      Hey Alf
      Good question, thanks for asking.

      So basically any kind of metal wire will work… Some better than others.
      The major issues to consider is cost of materials and longevity in the environment.
      Most metals will oxidize and corrode when left outside. This will make the surface less conductive and may also weaken the metal.

      To answer your question, copper will definitely work and it is an awesome conductor….but it will oxidize if left outside (think of an old penny).
      This copper oxidization is not a big issue initially, but over time a thick film of corrosion will make the surface less conductive.

      The other issue is cost. Copper is rather expensive these days. For a small project, this may not be a big issue, but if you are covering a lot of ground then it adds up.

      I picked aluminum wire as the best option for me because it is very cheap, easy to find and doesnt really rust/oxidize/corrode.

      Hope this helps,

  3. Thank you for this detailed info, it motivated me to do my own project. I used old wooden ceiling planks for fence frame and copper wire (the store didn’t have aluminium at the moment). The fence works excellent (zero slugs detected since it was installed). I would appreciate any feedback on my project if you have the time:
    http://spacepetuniareview.blogspot.com/2014/05/slug-wars-chapter-1-making-diy-electric.html

    Cheers!

  4. Thanks for your design Igor. I’ve seen others make fences like this, but your design is different. That’s a great idea using insulated wire and stripping one side of it. So long as enough insulation is removed so that snails will definitely come in contact with the bare wires, it will work and we have the added benefit that the wire is insulated from the wood and staples. Copper will oxidize in time but the oxidation is easily removed by going over it with a pencil eraser.

    I plan to make something similar, but instead of using a 9V battery I’ll try a lower voltage, maybe 6v. If that works it’s better because the snails would less likely be killed. And I’ll mount the boards vertically (actually use the sides of my raised bed). They wouldn’t have to move away from the fence, to be safe; they would just have to let go and fall to the ground. I think they might have a lesser chance of dying that way.

  5. Sorry, I meant to respond to the author Thomas, not Igor.

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