Meet My Mollusks

Limax maximus (Giant garden slug)

I find it amazing how one can go through life without ever noticing something, then once you learn about it, you see it everywhere.  Kinda like buying a new car and then realizing just how many of that model are on the road.   A month or two back I read a few books on snails and slugs for book reviews (I’ll share one next post) and now I am finding creatures I never knew about before all over my garden.  Certainly they had been there all along, yet why had I been unaware?

I’m starting to become privy to the secret mollusk world in my garden, and it’s a kick (I know, I need to get out more). 

I see banana slugs, the marauding European Arion, the tiny, but ever-so-damaging grey slug, but only last week did I come upon the giant garden slug.  Sheesh—you’d think I’d have previously spied an almost 6” long slug with a pattern like a leopard!  David George Gordon, in his The Secret World of Slugs and Snails: Life in the Very Slow Lane, notes that this slug can reach 8” long and travels four times faster than our banana slug.  Limax maximus is not from around here and was discovered by the originator of our modern system of classification, Carl Linneaus in 1758. 

This species can be carnivorous.   In Land Snails of British Columbia, author Robert G. Forsyth, maintains that this mammoth mollusk is more likely to eat fungi and rotting organic matter than live plants.  A positive thing from a gardeners perspective—especially since they can live 3-4 years.   A banana slug might take a different position on this visitor.

Monadenia fidelis (Pacific sideband) on the trunk of a vine

The second creature to recently make itself known is Monadenia fidelis, Pacific sideband snail.  What a pretty little thing.  Actually, for a native snail, it’s large—just under the size of the dreaded common brown garden snail.  Its shell, however, is flattened.  It gets its name from the light and dark bands of nut brown, auburn and gold on its shell and lives from Alaska to Northern California.

I didn’t recognize it when I first noticed it in the Land Snails of British Columbia field guide but sure enough, a month later I spied it making tracks on the trunk of a vine as I was pruning.  And wouldn’t you know, both my books indicate that the Pacific sideband overwinters in the crotches of trees and has been found as high as 21’ in the canopy.  Naturally it was at home in the woody trunk of my Dutchman’s Pipe vine (Aristolochia durior).  As I snapped its photo, I admired its sleek pinkish brown body.

Beer filled slug trap hidden amongst golden marjoram and Hebe

I use slug traps filled with beer for slug control in the garden and they work really well at keeping the pest species down.  Of course, it’s not the most pleasant of tasks to empty, clean and refill them, but it beats other forms of bait in price and is low in toxicity.  I use the traps (I like the Surefire brand) in the spring (this year was so cold I didn’t need them until recently).  In the arid summer, when humidity is low and temperatures are higher, the mollusks make themselves scarce.  At that time of the year all I end up with in the traps are beneficial ground beetles and a few miscellaneous harmless insects.  Better to just wash and store them when the weather warms and bring them out again with the fall rains; storing them again when we get regular frosts. 

Luckily I don’t find many of the native species of slugs in the traps–and when I see the banana slugs in the garden, I remove them to the woods.  I do find the imported Chocolate Arion slugs (in dark brown or beige), which do tremendous damage to my plants.   When changed weekly to bi-monthly in spring and fall, the beer traps work wonders to keep these guys under control.

© Colleen Miko, 2011

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About Colleen Miko

Colleen Miko is a certified professional horticulturist with 20 years experience in landscape design who has designed award winning gardens for the NW Flower & Garden Show as well as HGTV’s “Landscaper’s Challenge”. Colleen is a freelance garden writer and speaker who regularly writes "The Perennial Bookworm" where she reviews garden and natural science books, as well as a regular contributor to "WestSound Home & Garden Magazine" on a variety of horticulture topics.
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4 Responses to Meet My Mollusks

  1. Your observation about these critters seeking out moister pastures in the dry months definitely holds true down here. And since we gave up suburban-style irrigation the number of mollusks has declined in all but the wetter areas of the garden. Unfortunately the veggie patch is one of their favorite hangouts. Maybe it’s time to try a trap like the one you show. I’ve tried bottles of stale beer but they don’t seem to do much other than make the garden look like it should have a single-wide trailer in the middle of it…

    • Colleen Miko says:

      I have friends who cut holes out of the lids of margarine tubs and use them for slug traps, that’s a step up from the bottles of stale beer in appearance, and you can sink them most of the way into the soil. I can’t believe it’s not butter!

  2. Mary says:

    Hi, Colleen–Where do you find that slug trap?

    • Colleen Miko says:

      I have been looking for the Surefire brand traps this year and haven’t found a source yet. I used to get them from one of the mail order garden catalogs, but they don’t carry them anymore. They used to come in a pack of 3. I’ll have to look a little more as some of mine are nearing the end of their lifespan, which is somewhere (for me) in the 3-4 year time frame when I clean them up and bring them in both for the summer and then again stored for winter. They really decline fast if they get UV exposure in summer or are exposed to freeze-thaw.

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