Up Close: Slugs

Terrestrial slugs are invertebrate mollusks. Soft-bodied dwellers of damp or aquatic environs, most mollusks feature a flourish of shell. But not slugs. “Shell no,” they said, and ditched cumbersome calcium covers for more nimble navigation. 

Though visibly shell-less, many slugs have a vestigial shell beneath their mantle, that fleshy shield on their back. That’s right—slugs are essentially snails without the shell.



As you wrap up the day’s watering, listen closely for a wee chorus of “aahs.” These, of course, are the relieved sighs of appreciative garden slugs. The cool, moist, environment for your plants is exactly what these meddlesome mollusks crave. You’ve unknowingly created a luxurious day spa for slugs. 

Slugs burrow into cool, damp soil to keep from drying out—and to eat. Roots, leaves, stems, it’s all the same to a slug. Here’s a closer look at these glistening garden groupies’ modus operandi.



Moving at 0.03 mph, slugs are the slowest animals on the planet, and for good reason: Plants don’t move. No epic hunting speed needed. For comparison, a sloth is five times faster than a slug at a zippy 0.15 mph. 

These gastropods—literally, a stomach on a foot—are no-frills garden destroyers. Slugs hatch from eggs, equipped with optic and sensory tentacles, a skirt, foot, mouth, an anus and genitals—yes, plural—male and female.



For slugs, this life-saving goo works two ways: When being threatened, mating or even climbing up a wall, slugs churn out stickier, thicker, foamier slime. When cruisin’ through your garden, it makes its regular slime. 

Hot days and dry soil require making more slime, and that takes energy. And slugs, well, they’re not energetic. So they go underground, eating your plant’s roots. Then, in the evening, they’ll emerge (still hungry) ready to devour a garden in a night. 

Ever get this stuff on your hands? Slug-slime removal is a near-impossibility by design. Why? Slug slime is a liquid crystal, which is just wacky. Medical researchers recently synthesized slug slime for use in healing wounds as a flexible, sealing, dissolvable bandage.



Instead of breathing through a traditional nose or mouth, a slug respires through its pneumostome—Latin for air mouth—to supply a lone lung. Found on the right side of their mantle (the fleshy cape on their back), a slug’s blowhole opens every few minutes. 

Unlike sea slugs, land slugs can’t survive underwater. That’s why they drown in small cups of beer you might leave out in your flowerbed (wink, wink).

slug eating


Featuring about 27,000 microscopic teeth, a slug’s mouth—its radula—are reminiscent of a shark’s. A slug’s jaw cuts big bites, while its radula shreds those big bites into teeny tiny morsels. Slugs can eat double their body weight in one night, which probably shouldn’t be a surprise.



Birds and bees have nothing on hermaphroditic slugs. All slugs hatch with both with male and female reproductive organs. Slugs twist their penises around each other and swap sperm to fertilize the other’s eggs. Some slugs, like the leopard slug, make it a real show by dangling from a thick rope of slime.

black slug

Arion ater

European black slug, invasive
From The Big Apple to our own Burien by the sea, European slugs are to blame for many a garden’s gone-ness.

red slug

Arion rufus

European red slug, invasive
Surprise! It’s the black slug’s BFF, red slug. This common garden slug is equally responsible for your dahlia’s demise.

banana slug

Ariolimax columbianus

Banana slug, native
The world’s second-largest slug is our state’s beloved banana slug. Eating fallen leaves and mushrooms, this Northwest native can grow beyond seven inches. Yellow, white, or mottled with black, these guys live in established forests—not your garden. They’re the good guys.

leopard slug

Limax maximus

Spotted leopard slug, invasive
With a male sex organ as long as its body, these slugs rely on gravity to unfurl their goods. These dangling Don Juans hang upside down from a glop of slime, corkscrewing themselves around their partner and fertilizing up to 200 eggs.


Now that your noggin is filled with sure-fire slug facts, here are a few of the gazillion ways you can get them gone from your garden.


  • Beneficial nematodes are a killer option. Put these tiny little creatures into a garden sprayer, add water and soak your soil. These are like little, murderous sea monkeys who’ll gladly make a meal out of slugs and snails.

  • Copper slug tape gives the slimy turkeys a shock—not lethal, but big enough to deter. It’s one of the more expensive solutions out there.

  • Slug & snail baits use a myriad of chemicals to snuff out snails and slugs. Pick your poison—literally—from tens of choices, and hum “happy (snail) trails, to youuuuu” as they take a dirt nap.

  • Homemade solutions include a cup of beer, a pinch of salt or the ol’ cornmeal method. What’s the cornmeal method, you ask? Well, you put dry cornmeal in a jar, set the jar on its side, then slugs eat the cornmeal and die.

Do you have a solution that really works? Because seriously, these are tricky little fellas to eradicate—if at first you don’t succeed, slime, slime again.