Electric slug fence

[jim]

maybe the design could be "tweaked" to kill the b*ggers rather than merely put them off? or am i being dangerously over optimistic..... JimK

[Andrew Gabriel]

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.

[Andrew Gabriel]

?pid=434697&l=1c3f634c2f&id=1619546457>>>> No slug damage this morning!

That's fine, but I suggest to wait a bit - one night alone doesn't mean much yet.

Yesterday in the bright sun, the lengths of PVC and steel bowed in the heat a bit, like large bi-metal strips, so I really need slotted holes drilled in the steel. By evening when the slugs appear, it was all laying flat again.

Last night, there was a tiny leakage, just visible as a faint glow in the LED if I switched off all the lights. Only a fraction of a milliamp, but it will reduce battery life. I notice some soil has been splashed up the PVC by my watering (it hasn't rained here). I'm going to try some wax polish on the PVC if I get a chance before tonight, to enhance the water repellent effect.

[Roger Mills]

Yes indeed. Any thoughts on how well a copper frame would work - made out of

4 lengths of 15mm copper pipe with elbows at the corners?

Obviously, it would tarnish over time. Would tarnished copper still repel slugs?

[Jules]

:-) Not on that scale - was idly thinking some PVC pipe split down the middle to make the channels, then glued with normal pipe joint stuff to make them hold water. Disadvantage that it needs to all be level, unlike the electric version...

Ours do OK in the warmer months. But the garage has a dirt floor, so you can imagine what happens when the lawns are frozen solid :-(

cheers

Jules

[Stuart Noble]

I wouldn't bank on it

[Dave Liquorice]

Seems a lot of work. Why not buy it off the shelf complete with proper water tight joints? It's called guttering...

[oldhenwife]

?pid=434697&l=1c3f634c2f&id=1619546457>> No slug damage this morning!

It might not be permanent - it's only stopping slugs which are outside the perimeter. If the bed of earth/compost is on earth they might well come up from underneath - which is where they spend most of their time.

I'm surprised that you've lost autumn crocus to slugs, mine have given the best show ever this year and we're certainly not short of slugs.

Mary

[Jules]

Yes and no - I don't think guttering joints are designed for continual submersion, plus as the joints expanded and contracted they might pull dirt in and then fail. I expect it'd work for a few years, then need some tinkering with.

'course any moat system still needs clearing from debris, possibly much more frequently than Andrew's electrical system (where stuff will tend to blow/fall off, rather than collecting in a trough)

[Andrew Gabriel]

Yes, they can swim, sort of. I dropped one in the toilet, which had made its way indoors through a hole in the wall. It managed to wiggle to the side and then climb up the porcelain. It held on tightly enough to resist flushing.

[bof]

In message , Andrew Gabriel writes

Wrap 'em in toilet paper first, then flush, that sorts the buggers.

[Andrew Gabriel]

These are new bulbs. They only arrived and were planted 3 weeks ago. The same bed is stuffed full of bluebells in spring, and the slugs/ snails never manage to make much of a dent in them, but they're well established.

[Jules]

Yeah, I'll just go and toilet-paper the slugs in my garden moat. My neighbours would love that. ;-)

[The Medway Handyman]

Exactly. Wouldn't stop your Ninja Slug would it?

[The Medway Handyman]

One of them highly trained Ninja Slugs.

[Owain]

Imagine if you were without your spectacles and thought it was a turd in the bog. Then the turd started climbing up the pan towards you ...

Owain

[geoff]

In message , Andrew Gabriel writes

My army of frogs seem to handle the slugs here

[Matty F]

The resistor would be just to limit the current in case of a short, e.g. a whole pile of dead slugs across the wires!. I already have a fuse but I don't want that to blow or I could lose my garden overnight. According to the OP, only a very small current is enough to stop the slugs.

[Mark]

1000V should do it. Or buy a python.

[Andrew Gabriel]

Yes. I didn't want to kill them, because a line of smoldering slugs around your flower bed doesn't look good, and they are food for things like hedgehogs.

Also, I have an LED to let me know if there's any current leakage, and doubles up as a battery test. In the event of a slug arriving with a crowbar, I need to limit the LED current to 20mA to avoid damaging the LED. If you want to see if it's working, the LED flashes when a slug actually gets a belt. I also used it to test the effect of watering the area.

Also as I mentioned before, I want to limit ground currents, as I don't know what effect it might have on other wild and domestic animals which roam around, and I have no wish to harm. I do know livestock is very seriously affected by leakage currents at levels you can't even feel, which is why you have to be very careful with earthing of electricity supplies on farms.

[The Medway Handyman]

Ninja frogs?