Slugs in the garden can be a huge problem and apparently copper is a good slug repellent. If you encircle your plants with copper tape, it will keep the slugs out. It must work – since there are a number of copper tape products on the market designed to get rid of slugs. But does this really work?
Why Does Copper Work?
There are two reasons given for copper working as a slug repellent; toxicity and electric shock.
Copper is a known poison for many organisms and some copper chemicals are used to disinfect and kill organisms. It seems to make sense that copper tape or copper wire would have the same effect. If you think about this for a minute you will realize this can’t work. Most homes in North America use copper pipe to deliver water in our homes. If it were toxic – would we be using them?
Copper compounds may be toxic, but copper metal is not.
The green patina developed on copper metal over time is a copper carbonate salt and could be toxic.
The second claim is that the slime from slugs connects with the metallic copper and the slug gets a small electrical shock from it. This is unpleasant and slugs stay off the copper.
I have not been able to find any scientific reference showing that this is true. It is just repeated thousands of times. So let’s apply some logic. You can create a simple battery by inserting copper wire and a galvanized nail into a lemon. This will produce a small current that is measurable. You need 3 important components to make this work; two electrodes of different metals, and an electrolyte–the juice in the lemon. If you want to see a lemon battery in action have a look at this video.
In the case of the snail we have the copper, and the electrolyte in the form of slug slime.The second electrode is missing. Also missing is the connection between the two electrodes which allows the current to flow. I don’t believe that putting slime onto copper will produce an electric charge.
Does Copper Repel Slugs?
Let’s look at some video evidence.
Source: Does Copper Work on Slugs? See and Decide for Yourself! Just for fun!
Copper pennies and wire do not seem to work. Most products on the market are a type of copper foil or copper tape so this might work better and in fact some people suggest that a wider strip is better than a narrow strip.
Source: Copper Tape vs Slugs
That seemed to work quite well. But what about this video?
Source: Garden Pest Update: Slug vs Copper
Maybe some slugs hate copper more than others.
And this one:
Source: Slugs vs Copper Tape
How to Get Rid of Slugs
Jeff Gillman, one of the Garden Professors, commented “When I’ve tested copper the slugs seemed to have a slight preference for not crossing it, but would if that was what they need to do to get where they were going. I’d call it a mild repellant” . I think this is a good summary. Slugs will not go out of their way to cross copper in tape form, but it is not a fool proof solution.
This myth is busted!
The Latest Science
The latest testing found that bread dough and bread dough slurry were the best attractant for various species of slugs and snails. It was more effective than beer.
Getting Rid of Slugs and Snails
There are all kinds of methods for getting rid of snails and I have reviewed several of these including:
- Eggshells Control Slugs – Do They Really Work?
- Getting Rid of Slugs With Coffee Grounds
- How To Get Rid of Slugs With Beer
- How to Get Rid of Slugs With Copper
- How to Get Rid of Slugs with Diatomaceous Earth
References:
1) Photo Source: Aspen Grove Gardens
thanks very useful saxed me some pennies
i still would like to know if sand around your garden will keep the slugs out also .
will oyster shells stop slugs.
addison
Someone else posted about oyster shells. A quick search found only people who have tested it and say it does not work. Don’t know about sand – but there are so many kinds of sand to test. But I doubt sand works. Slugs are designed to crawl over things in nature – where there is lots of sand.
I used crushed oyster shell around my plants and it works as long as I cover the full area, out to the tips of the branch line, and refresh it if plant debris from overhanging plants fall onto the shells. Debris acts as a bridge that the slugs use to cross to the plant. I also use Sluggo (iron pellets) with less success. Pacific NW is slug heaven.
The copper tape works when it’s wet which the second video shows. The problem is keeping it wet.
Thanks for the comment. I had noticed the copper tape was wet. So I guess if you are willing to spray it every hour it works!
I don’t think wet is enough. I invested in some adhesive copper strips (before reading this post) and conducted my own test this morning – with dew all over the copper strip. Slugs were harvested and put to the wire, so to speak. They crossed it without batting a tentacle. Back to pellets for me… (Love the blog!)
You could try using 2 copper tapes with a 1.5V battery connected between them. (I’ve not tried it myself) I’ve long given up and gone back to slug pellets
Today’s slug pellets are probably more environmentally friendly than either manufactured copper, or batteries.
My only slug repellant is the colony of leopard slugs that lives on the property. They’ve never touched anything in my garden aside from smaller slugs and dead plants.
So, perhaps what is needed is a bi-metallic barrier, say a strip of copper tape, a small gap, then a strip of aluminium foil. Slug may cross one but will get a shock when he straddles both, and hopefully turn back.
Oh no thank you for the video was most helpful ! I think will try my eggs shells and sand idea ! Save a bit of money !
Your welcome. Egg shells don’t work well either. Apparently diatomaceous earth works–but you need to use the one made for gardening, not swimming pools.
What if you twisted a copper and a galvanized wire together? Those two metals plus the slime would create a current?
I believe the two wires would have to be separated and the slime make the connection for this to work, but I am not sure. In any event I have never seen this as a solution to the slug problem.
Could you put copper tape and plumber’s tape parallel and about 1/4 inch apart?
You could, but it won’t work.
I was suckered in to buying copper tape. DID. NOT. WORK. http://imgur.com/Y6P8xER
That is one of the reasons I write this blog. There is too much useless stuff on the market to buy. Only the truth will set us free.
Simple test. Fit copper tape round terracotta pot. Place 6 slug pellets on top of pot. Leave over night.
Result: 2 large dead slugs in morning. Case proved!!
What case are you trying to prove?
Great to see… to add to the video list, I liked this one on the topic: http://www.youtube.com/watch?v=ZFn9TT_rlXU
Same basic conclusion.