In article ,
writes:
On 27 Sep, 11:03, (Andrew Gabriel) wrote:
In article ,
Colin Wilson o.uk writes:

Decided to make an electric slug fence yesterday, after my new
autumn crocus shoots got eaten for the second night in a row.

http://www.facebook.com/photo.php?pi...&id=1619546457
http://www.facebook.com/photo.php?pi...&id=1619546457

No slug damage this morning!

Hehehehe how are you powering it, can't quite tell from the pics

PP3 (9V) battery, in series with a 470 ohm resistor and a high
efficiency LED (plus the earth rod resistance). The LED lights
to tell you there's some leakage current (high efficiency one
means you can see even fraction of a milliamp leakage at night).
It flashes quite brightly when a slug touches the contact.
Given the dramatic effect on a couple of slugs and a snail
which I saw approch it last night, I suspect a much lower
voltage would work fine too. It's probably not safe to use
such a scheme if you have livestock nearby, due to their
vulnerability to very low earth leakages.

Construction is 25mm PVC conduit with 12mm galvamised capping
screwed to the top. The profile of the capping is perfect for
rain water shedding from the top. I tried a deluge from a
watering can rose, and even that didn't cause the LED to light.
Just touching the rail whilst kneeling on the ground generates
enough current to light the LED though. Water droplets bead on
the surface of the PVC, so it won't conduct. It might be that
it needs lifting and wiping clean occasionally to maintain this,
but I haven't had it deployed for long enough to know yet.
Ground needs to be very level. I filled in a couple of dips
under the fence with some old building sand. A couple of tiny
slugs appeared inside the area, presumably sleeping inside the
fence when it was positioned. After removal, no more were seen
inside. I'll keep an eye out over the next few nights. Can
easily test the battery just by touching the rail and ground
with a hand. Operation probably requires that the area stays
damp, but a) that's needed for the plants anyway, and b) slugs
don't tend come out when the ground is very dry.

Fantsastic! I've taken the liberty of cross-posting from uk.d-i-y to
uk.rec.gardening where I'm a long-term lurker, they'll be interested.

So after a few days, how's it doing?

Before I made it, every new shoot was eaten back level with the
soil every morning. Since making it, only about 1/6th of the
shoots have been eaten back to the ground, and another 1/6th
have some damage. I've checked a few times during the dark, and
found there were still some small slugs and one tiny snail, which
I have removed. Difficult to tell if they're getting in, or were
in to start with, but I suspect probably some of each. Trying to
search the whole area in the dark even with a bright torch was
not easy. Then I realised that each one I had found had its jaws
on one of the new shoots, and because they're planted in a strict
pattern, they're actually quite easy to find now.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]