You put out some cheap beer in a foil tray, and the slugs dive into it by the dozens, drowning themselves in a slow motion dipsomaniacal frenzy. Now you have a tray full of beer-sodden slugs. At which point the opossums show up, to eat the slugs, and their drunken cavorting in the garden attracts raccoons, and the next thing you know, you’ve got adolescent raccoons having noisy fights on your back porch and passed out possums littered about the garden. It’s chaos!
I have used such a fence on my raised beds for the past two years, after unsuccessfully battling the Portland Oregon slugs for a year. Some points learned by version 3.5 of the fence, in case you want to try…
What does not work:
used coffee grounds. Slugs ooze right across regardless; rain washes them off.
copper and copper/zinc fences. Don’t work; slugs cross anyway.
salt, beer, poisons. These don’t keep slugs out, but rather randomly reduce the population. Plus you have to tend the traps.
Fence notes:
I found that for our local slugs 6 v deters, but 9 v kills . The dead slug then sits frying on the wires all night, discharging the battery. Therefore repelling is objectively more effective than killing.
Galvanized wire lasts but one season in the rain, then corrodes so badly it forms a crust or even breaks. Second season I switched to aluminum wire. There’s no corrosion, and it deters just as well. Apparently the wet slug body conducts current through the Al2O3 layer.
I used insulated staples after finding that current leaks through the wood via the staples. An ohmmeter allowed me to calculate the effect on battery life: just the leakage would discharge the battery in one week.
For the same reason, I placed strips of rubber bathtub liner under the wires, as there was discharge over the wet wood after rain. Now the fence measures infinite resistance.
Slugs typically test the wire twice, then move along the wire, try twice more, and finally go away. These smart little buggers can learn. Also, it’s cheap entertainment to watch them try.
Occasionally a slug will get across the wires. It can cross the bottom wire at an angle, traverse horizontally in the gap, and then cross the top wire.
Another amazing behavior I saw is to arch over the top wire, moving the arch along the body from head to tail, never touching the top wire. This really happens. Our slugs seem to have “crossing a noxious substance without touching it” as a built-in behavior. Yay, evolution.
A manufactured strip with interlocking electrodes, like combs, would solve the above problems. But even Alibaba lists no such item.
You can quickly test the fence’s strength directly with your tongue. You’ll feel the stronger “bite” from the positive electrode. Therefore I always connect positive to the top wire in order to motivate turning down and away from the garden.
Yes, it works, is more effective than any other method I’ve tried, and saves time and vegetables. Except of course for the many hours designing, shopping, experimenting, and building. But I enjoyed that part for its own sake, as did the fascinated Home Depot staff.
So let the jokes and sarcasm begin. Let me help. Did you know that a slug’s anus is in the middle of its back?
Yes, I’ve been running a similar system using these buggers: https://cdn.mcbuero.de/images/items2/lega7-145101.gif
As containers for the batteries I used small junction boxes / distribution boxes; these cost about 50 Euro-cent each over here. https://images-na.ssl-images-amazon.com/images/I/41GsaI1C40L.jpg
TWO IMPORTANT HINTS: your wire shouldn’t be too thin, and on the side. First I went with a 0.5mm stainless steel wire which I built on top of my garden bed walls. Slugs would try to cross it and get shocked. But somehow they would fail to retreat (probably cramping too much) and stay on those wires, slowly getting cooked.
Yes, that’s metal as fuck.
However, where those slugs rested on the wires and closed the power circuit the wire would heat up too much and break. Each morning I would remove like a dozen crunchy slugs and replace the wire with a new one.
So, better pick a thick one. I use 1.2mm instead of 1.6, and so far it seems to work out. I will however steal the idea using staples; didn’t do right away since I wasnt sure if after rainfalls etc, the water might conduct electricity and drain my batteries.
EDIT: okay, just read the part about the rubber. I’ll look what I can come up with over here.
Okay, so I just hit my favorite hardware store, your remark about aluminum still echoing in my head. I bought some “Aluminum tape” from a brand which sports a Rhino and tested if it conducts electricity. It does.
The plan now is to first apply a layer of simple duct tape all around the garden bed, then cut the aluminum tape length-wise into strips narrow enough to be applied onto the duct tape.
If everything works out, the duct tape should isolate towards ground and the aluminum tape should conduct. Stay tuned.
Have you thought of using a solar panel to power the lines? Also have you thought of using metal strips/bands instead of wire? You’d have more surface area and would make it much harder for the slugs to try to avoid the setup.
Isn’t it amazing? We have a built-in voltmeter in our mouths (keep it under 12v), and a built-in analytic chemistry lab in our noses. They are often convenient.
