10 Neat Things About Slugs
by Shauna Dobbie
by Dorothy Dobbie

The Local Gardener magazines, Ontario Gardener, Manitoba Gardener and Alberta Gardener, are published by Pegasus Publications Inc.

Drawing on her 30 years' experience as a senior executive in the magazine publishing industry, Dorothy launched Manitoba Gardener in 1998, initially running the business out of her home. Two years later, Dorothy's daughter Shauna, living in Ontario, jumped into the fray with Ontario Gardener. And two years after that, they started Alberta Gardener. Visit us at and register for our "Ten Neat things" newsletter. Watch Shaw TV for garden tips and Listen to CJOB for the Gardener Sundays at 9:08

July 17, 2011

1. Not animal, vegetable or insect.

Slugs are none of the above. Slugs are mollusks as are oysters and snails. There are about 30 kinds of slugs out of as many as 200,000 species (or more) of mollusks. To discourage slugs in the garden, there are many possibilities: diatomaceous earth spread around a favoured plant or coffee grounds to the garden are but two.

2. Follow the trail of slime.

Slugs are hygroscopic, meaning they are covered in two types of liquid, one quite thin and another, thicker and stickier. The thicker slime is a defense mechanism, which makes slugs hard to grip by predators (squirrels, some birds and some beetles eat slugs). The thick slime also tastes very nasty. Wherever they travel, slugs leaver a tell-tale trail of slime that is recognizable by other slugs who may be looking for love from their own kind - or looking for someone to eat. Some slugs are carnivorous and they like to eat their cousins.

3. Slug sex.

Slugs are hermaphrodite; they are equipped with both the male and female genitalia. The receiving genital openings are near their heads. No, they don't mate with themselves (Ugh! Way too weird). However, they are very efficient maters, taking full advantage of their hermaphrodite condition by inseminating each other at the same time.

4. There can be a catch in slug sex.

Banana slugs have very long penises and sometimes they get stuck to their mate. (It's hard to disengage when you are covered in slime.) If this happens, the mate will bite off the offending appendage to free itself. The now female partner is free to mate again, but only on the receiving end of the favours. This is called apophallation. If you have a strong stomach and want to see this for yourself, go to

5. Autoapophallation.

Fully erect slug penises are very long in comparison to their bodies. The grey garden slug's penis is half its body length. Occasionally, slugs cannot rid themselves of erections after mating and separating successfully. So they bite of their own penis. Ouch!

6. Toothsome?

Slugs can eat twice their weight in a single night so their teeth wear out often. No problem. When one row of teeth wear out, a new set rolls forward like a conveyor belt. It is estimated that slugs have 25,000 teeth!

7. We only see the tip of the slug population.

Slugs feed in rotation. Only about five per cent of the population feeds at one time. The other 95 per cent are resting, having sex or . in a slug infested area, there are about 392,040 slugs per acre. It would take a lot of beer and years to kill them all, even if they didn't lay about 200 to 400 eggs a year!

8. Body changers.

Slugs have the ability to take on a body shape that suits the purpose of the moment. They can become fat, slimy and unwieldy in the presence of a bird or other predator that can actually stomach their taste, or they can become long and extremely skinny when trying to enter a small opening or crack.

9. Size of slugs.

Some slugs are very tiny - only a few millimetres long. But be thankful you don't garden in California where one slug can weigh as much as a quarter of a pound!

10. Just how sluggish is a slug?

A fast man can cover 100 yards in 10 seconds. A fast slug would take two hours. Their average speed is two feet in 43 seconds.

-Shauna Dobbie

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