What's Bugging You? Slugs


When the soil begins to warm in spring it signals many garden creatures to prepare for that warm season ahead.  One group of such creatures is the garden slug which have spent much of their winter deep underground in temperatures that rarely dip below 0 degrees C.  This is also true of their eggs which go through a process of supercooling to lower their normal freezing point.

For the most part, we gardeners view slugs as voracious leaf eaters that prey upon our plants under cover of night.  If they would only remain underground (which many do) eating fungi, organic decaying matter and releasing soil nutrients, we would be more understanding!

Slugs are mollusks which are very much like snails, but without bones and a shell.  They have a lifespan of 6 years.  

Their bodies range in size from 10-20 cm. in length and are usually grey or light brown/tan in color. The living conditions favored by slugs are dark and damp. They hide during the day under rocks, boards, leaves and other garden objects.  Slugs have soft muscular bodies which are covered with a slimy mucous that tastes bad to predators – birds, frogs, toads, and beetles.  The mucous also contains a pheromone that attracts other slugs to a feeding location. This mucous has many interesting properties that are being studied by scientists.

A slug’s eyes are at the end of the long tentacles on top of its head. The short tentacles that point down are used to smell with the four noses. Under the tentacles there is a radula or a tongue-like organ with thousands of teeth. These teeth handle food before ingestion.

Slugs have both male and female reproductive organs.  They usually lay about 30 clear round, jelly-like eggs in the ground or in their favorite dark and damp hiding spots. Slug eggs appear in a slimy mass and are clear, grey, white, or brown.


There are many ways to get rid of slugs in your garden.  If you have pets or small children, it is best to avoid commercial slug pellets.

Less harmful slug remedies are as follows:

Have flashlight slug hunting nights with the kids – look under rocks, leaves, objects and wood. See who can collect the most slugs in a one-hour time period. 

Apply nematodes, mixed in water, to your garden soil.  The Phasmarhabditis hermaphrodita, a nematode worm, will kill slugs and snails.  The soil must be over 5 degrees C before the application. 

I think most of us have heard of the slug beer trap.  Fill a 250 ml. empty yogurt container about 1/3 full with a cheap beer.  Sink this container into the ground so that the rim is even with the soil.  Slugs love the yeast smell of beer and will fall in and drown.  I have tried this myself in my garden and it works very well.  I would also recommend that you place any slug attractants in an unused corner of your yard - away from prized plants for obvious reasons.  Your attractant will attract neighboring slugs as well. 

The scent of the perennial Astrantia, rosemary, fennel, and wormwood will repel slugs. 

Lay down lengths of copper tape.  The slug slime reacts with the tape, causing an electric shock each time they cross over it.

Spread diatomaceous earth on top of the soil in slug infested areas.  The sharp bits will cut through the slug’s skin causing eventual death.  Diatomaceous earth must be reapplied after rainfall.

Caffeine will kill slugs and snails. 

Do you eat grapefruit?  After you eat the grapefruit do not scrape out the dome-shaped rinds. Prop up the half of the rind with a small stick and leave overnight.  Check the inside of the rind each morning.  I guarantee you will find some slugs.  Sprinkle the slugs with salt and throw in the garbage.    

If you have chickens, they will eat the slugs.

A pile of old lettuce leaves in an unused corner of your garden will also attract slugs. 

Slugs are toxic to pets but the typical garden slug is not toxic to humans. They do, however, carry the rat lungworm parasite which can transfer to the brains of pets and humans as well.  It is transmitted in the slug’s slime residue on salad greens and vegetables.  Always, always wash your vegetables before eating. 


The largest terrestrial slug is the 30 cm. long ash-black Limax cinereoniger.  It is found in Europe and eats fungi.

Slug eggs can remain dormant for years; hatching when the conditions are just right.

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