Rumours of copper's slug-&-snail-stopping super powers have been in circulation for as long as I can remember. From copper foil tape to copper mesh, I've even heard of gardeners lining their raised beds with copper plumbing pipes!
I personally have always used copper tape or copper mesh to deter slugs, and anecdotally it seems to do the trick for the most part - but I've never spared much thought for how it's actually supposed to work.
So, what does copper tape do to slugs and how does copper tape work? A quick google will produce a flurry of competing theories:
Electrical Current ; some people assert that as the slug or snail passes over the copper a minute electrical current causes them discomfort. This is allegedly due to the difference in electrical potential between the copper and the slime, (shocking!)
Toxic to Gastropods ; others say copper repels slugs & snails due to to its toxicity to them as it oxidises.
Sharp & Serrated ; others still seem to think the copper tapes sharp or serrated edge deters slugs and snails from crossing it.
Unfortunately, with no scientific literature on the matter and with so many conflicting colloquial theories, maybe the question instead ought to be will copper tape stop slugs?
And the answer to that seems to be "YES"; many gardeners seem to weigh-in to support the idea that copper stops slugs and snails , and I count myself among them.
But we decided to do something a little more substantive than just talking about it - so we put it to the test:
I learned a lot from out little experiment:
Slugs & Snails do seem to avoid crossing copper tape, and it does seem to cause them discomfort.
Larger gastropods are more resistant to copper's effects, and can sometimes 'stretch' over the barrier.
The thicker or wider the barrier of copper, the more effective it seems to be (particularly against larger gastropods).
Though clearly a valuable anti-slug and snail tool, it cannot be expected to stop 100% of slugs and snails 100% of the time.
This confirms my own feelings on copper tape as a slug deterrent - does copper tape work? Yes! Is it a fool proof method? No. But even so, copper tape can be a valuable tool in your slug and snail defence arsenal.
So should you use copper tape to deter slugs and snails? I would say probably, you're certainly better of using copper tape than using nothing at all.