Slug

2013 November 13

“Sorry, Squire, I’ve ‘ad a look ’round the back of the shop, and uh, we’re right out of parrots arthropods.”

[pause]

“. . . I’ve got a slug . . .”[1]

Actually I’m not really out of arthropods. By the time this post goes live, I will have had all spring, summer, and fall to find more. But I’m writing this near the end of February 2013[2], and at the moment I’ve got all my usable photos from last year prepped and queued up. And the 2013 arthropods haven’t exactly started rolling in yet. So, you get this slug that Sam found under a pile of shingles on November 11, 2012. Here it is all curled up, depending on its layer of slime to disgust and repel potential predators:

Anyway, a slug is basically a shell-less snail. They are mostly nocturnal, because they’re susceptible to drying out in daylight, so you either find them in moist vegetation after the dew has formed, or under sticks, boards, or rocks. Slugs that get caught far from cover when the Sun comes up are in deep trouble. Some days, when pushing my bike up the hill on my way home from work, I’ll see these glistening trails of dried slime across the pavement, from slugs that tried to cross the road overnight and didn’t make it. And each one ends with a shriveled slug corpse.

This one was perky enough, though, with its stalked eyes poked out, and it ran as fast as it could (which, all things considered, wasn’t very fast).

It’s a little blurry, but we can also see its breathing hole. For some reason, a slug’s respiratory system is asymmetrical, with just the one hole on one side.

So, anyway, people mostly don’t love slugs. They come out at night and eat the plants in your garden. And I see now that I neglected to get it to crawl onto a glass plate so that I could flip it over to photograph the rasping-tongue action that it uses to shred plant leaves.

A lot of things prey on slugs, like predatory ground beetles, but slugs also breed like crazy and do a pretty good job of hiding during the day. You can find the eggs pretty easily under rocks in the spring. They are these clusters of transparent spheres laid in cavities under the rocks.

There are all kinds of tricks for reducing slug numbers in your garden. Some of them seem contradictory. For example, some recommend that you remove rocks, boards, and other things that slugs might hide under during the day, so that they will leave. Others recommend adding rocks, boards, and other things so that slug-eating predators have a place to hide, and will then eat all the slugs. I kind of suspect that if you use insecticides on the garden (which would wipe out your predatory beetles), then you have to do the first option, but if you don’t use insecticides then the second approach will work.

There are dozens of other things that people recommend for slug control, so regardless of your situation, there should be something that works. These include:
- hand-picking;
- laying down boards, orange peels, or other attractive items, and then flipping them over every morning to harvest the slugs;
- putting out dishes of beer for them to drown in;
- baiting them into traps with dog or cat food;
- using strips of copper as a barrier (they evidently hate crawling on copper, although it doesn’t kill them);
- putting down dry, scratchy things like eggshells, diatomaceous earth, or sandpaper (barrier method similar to the copper);
- keeping chickens or ducks and letting them run in the garden (although sometimes they’ll eat your crops too, so watch it);
- buy predatory snails (only works in warm climates);
- poison them with iron phosphate granules (which you can buy with cutesey names like “Sluggo” and “Escar-go”);
- use methaldehyde baits (which are toxic to other animals too, unlike the iron phosphate which is pretty specific to slugs);
- coffee grounds (although the effectiveness of this is disputed, which doesn’t surprise me, because all the really nasty-tasting stuff in coffee[3] is supposed to end up in the drink, not stay in the grounds);
- spray a 50/50 mixture of vinegar and water on the slugs;
- spray a 1/4 mixture of ammonia in water on the slugs;
- plant mint or sage as a slug barrier

And I’m sure there are many others. I doubt we’re going to be testing these much, though, because in our climate slugs just don’t seem to be much of a garden issue. While we do have slugs, they don’t seem to be numerous enough to be a real problem, and the ones we have are generally fairly small. I think it might be another case of the harsh winters killing the slugs, so that we don’t have to.

———
[1] Does it talk?

[2] Yes, my posting queue has gone up to 9 months. Sandy has joked that if I keep this up, when I die the blog might live on for another decade just on the queued-up posts.

[3] Caffeine is very bitter, and as far as I’m concerned[4] it is by far the nastiest-tasting thing in the coffee bean. And once you leach that out, I doubt that used coffee grounds have properties much different from sawdust. Still, there is probably something to the idea of using bad-tasting substances to repel slugs. Slugs are basically all tongue, and probably taste everything that they crawl over.

[4] As it turns out, the way that bitter substances taste probably varies a great deal from person to person, which may account for why some people say that they like things that are bitter, while other people hate them. I suspect that even though we all mostly agree that some things are bitter, the actual sensation that we get from bitter flavors are not at all the same. The sensation that I call “bitterness” is a deeply unpleasant and foul sensation that I can’t imagine ever getting to like, and caffeine has it in spades (as does alcohol, latex, and dark chocolate). I can tolerate it a little bit as long as it is heavily diluted by other flavors (particularly large amount of sugar), but from my point of view it never improves the flavor over having it be absent. Meanwhile, a lot of other people talk about how they like a bitter “bite” in things like coffee and beer, which leads me to think that they are actually perceiving it as a different sensation than what I get, one that is more tolerable and can actually compliment other flavors rather than interfering with them.

2 Responses leave one →
  1. November 13, 2013

    I tried the pan of beer idea. It worked, but a pan big enough to drown snails and slugs requires a whole beer to fill it. Not worth it. Instead, at least with snails, I found it much easier to go outside at night and squish them. The number of victims fell exponentially and after about 5 days of stomping around the yard, slaughtering the snails, we had them under control.

  2. Anne Bingham permalink
    November 13, 2013

    Thanks for the excuse to watch the Dead Parrot sketch!

    Beer and a beer bottle or baby food jar works better than beer and a dish. Use just enough beer that it doesn’t spill out when the jar or bottle is turned on its side. You can sink it into the ground so the entrance is level with the dirt. We have nosy dogs and raccoons in the area, so I’ve had better success when I’ve secured the jar/bottle under a rock or board.

    An unintended consequence is that earwigs also love beer. I’ve tried the cheap brands such as Old Milwaukee but so far both slugs and earwigs prefer Leinie’s.

    I’ve also tried a yeast/flour/sugar/water mixture but my slugs and earwigs, being from Milwaukee, prefer the real thing.

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