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Slug experiments

FireFire LondonPosts: 10,928
edited 25 July in Tools and techniques
For a couple of years I have been testing out different ways to limit slugs in my front and back gardens. Conventional tools such as using wool, egg shells, coffee, gravel, copper bands, seems to have slowed them down in my gardens not one bit. But I wanted to run some small 'citizen science' tests to measure results more accurately, rather than just by impressions.


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I usually put vulnerable plants (such as dahlias) in pots, but here slug flock to a phlox plant in a tall pot.

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The slugs seem to enjoy sheeps' fleece. They choose to huddle in dry coir, which is intriguing.

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In 2019 and this July I have used the front garden raised bed as a nemtode test area. Observations are here. In summary, following the instructions as closely to the letter as possible, I found that it hasn't reduced the numbers at all in that area.
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The back garden is 7x3.5 metres.


In the back garden (above) I have done ten slug hunts, since 1st July 2021, around every other night, with a torch, around 11pm for about ten minutes. I snipped the slugs. For the ten nights I counted these numbers of slugs:

52
32
33
42
36
75
56
38
55
32
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I will go on to test beer traps, using different materials and sizes of containers for the beer, different beers at different heights from the ground. (Yes, I would rather drink the beer). From what I read, it is the smell of the yeast that attracts the slugs. As they can move quite happily under water, I'm not sure why they go on to drown, but some do. 
These three, for example, were quite happy to sip beer and slither off. They didn't fall in and didn't drown.
 



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So - here are the beer trials. I put the five pubs in the seemingly most heavily slug-infested areas of the garden.

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Plastic soup pot, one can of Boddingtons bitter, buried, not full. (The Golden Apple pub)


After four days. No slugs

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About one metre away (The Red Rose pub)
Pint glass, one can of Boddingtons, buried, full.


After four days 16 drowned slugs (crusted, so, arguably, no more slugs would have fitted on the surface)



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Glass bowl, two cans of Fosters lager, not full, not buried (The Pea and Poppy pub)

After four days: zero

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Jam jar, less than one can of Boddingtons, buried full (The Fennel and Fork pub)


After four days 16 dead slugs (crusted, so, arguably no more slugs would have fitted on the surface)


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Plastic soup pot, one can of Fosters, not buried, not full (Hotel California)


After four days 13 dead slugs

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Plastic soup pot, one can of Fosters, buried, not full - in the worse area of all. (The Queen Virginia pub)



After four days 35 dead slugs



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So, what are the intial thoughts? The material doesn't seem to matter. Whether then pot is full, doesn't seem to matter. The placing matters a lot, although some of the worst areas (the Golden Apple), where I usually find most to snip - up to 30 at a time - had no slugs in the pub. Does burying the pot help? It's hard to say. Fosters v Boddingtons? I don't think it has made a difference.

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Normally I would be snipping around 130 slugs a week at the back this year. The pubs caught 80 slugs on their own, in four days, with little effort from me, so that is a great result. I have tried pubs repeatedly in the past with little success (Special Brew in two sites through June). This might be because some of the areas that I imagined would be best to put a pub, actually had zero results in the test. Also, I wasn't snipping at all over the four day test and left the slugs to their own devices. Maybe there is more success if you let the beer brew in hot sun for a few days... But largely, if I was putting out one pub and getting 20 a week, this would be no where near enough to make it worth the effort. I caught so many slugs, largely because I had so many pubs in varied places.

A wider mouth would seem to be better as it doesn't crust over with slugs so fast - although the pot needs to be deep enough to drown in - so that means more beer... which is expensive.

Some slugs (as pictured) are happy to sip and run - so imagine a lot more slugs were attracted to the pubs but didn't drown.

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So far I have picked the slugs out and left the beer in (partly because it's too expensive to keep buying new beer and the old stuff doesn't stink yet). I'll see how things are in another four days.

One interesting question is whether it all makes any difference. I snip 130 slugs a week or so in medium year like this and doesn't seem to make a difference to the population. In a bad year I would be catching into triple figures every night in the 4x7m area, seemingly without making a dent.


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Posts

  • B3B3 Posts: 18,762
    What is the effect of rain  or plant watering diluting the beer? Have you sheltered the traps?

    In London. Keen but lazy.
  • pansyfacepansyface PEAK DISTRICT DerbyshirePosts: 18,626
    I’d drink the beer and then I wouldn’t care about the slugs.🙂
    Apophthegm -  a big word for a small thought.
  • FireFire LondonPosts: 10,928
    We had no rain during the four day period. But, yes, they are pretty sheltered.
  • FireFire LondonPosts: 10,928
    edited 25 July
    pansyface said:
    I’d drink the beer and then I wouldn’t care about the slugs.🙂

    That is one, very valid approach, for sure.
  • FireFire LondonPosts: 10,928
    I just went out the back and snipped 42 slugs ( a cursory hunt, not looking under pots and plants etc). at 9.45pm. If I went out at 2am, I would probably catch about the same again. 
  • LiriodendronLiriodendron Scariff, County Clare, IrelandPosts: 6,997
    Congrats for tenacity, and doing a comprehensive study, @Fire.   :)

    For what it's worth, I've had success with the cheapest available beer (Asda Smartprice, as it happens - and you'd definitely not want to drink that one!) in glass jam jars, the sort with sides that slope inwards at the top.  I suspect this helps stop inebriated slugs from slithering out so easily.

    Shelter from rain seems useful; commercial "slug pubs" have a sort of hat on stilts over the top.  And I'm told that orange squash works as well as beer, though I've not tried it. 
    "The one who plants trees, knowing that he will never sit in their shade, has at least started to understand the meaning of life."  Rabindranath Tagore
  • SueAtooSueAtoo DorsetPosts: 222
    Many years ago i had some slug pubs that consisted of a cylindrical pot with pointed end to go into the ground into which fitted another cylinder with slots and a protruding tab which acted as a sieve, easy to empty and retain the beer. Not been able to find them for years. Would pubs still give you the slops when cleaning up?
  • FireFire LondonPosts: 10,928
    I will try Guinness and also the yeast and sugar mix that people often recommend.

    I'm not really holding out any hope that any of it will make much of  a difference or allow me to grow herbacious perennials (esp if my direct neighbours do nothing), but I do find it interesting.

    There might, of course, be a max population of slugs per square metre of garden, and by knocking out so many, I am merely creating a vacuum for more to come and fill...
  • FireFire LondonPosts: 10,928
    edited 25 July
    SueAtoo said:
     Would pubs still give you the slops when cleaning up?
    Asking pubs for ex-beer is an interesting idea. I do worry that using real beer might attract every slug within a ten mile radius.

  • B3B3 Posts: 18,762
    Hide the pubs in  next door's garden.
    In London. Keen but lazy.
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