Slugs Pest Guide

The word “slug” is actually a term of convenience rather than accuracy since slugs are absolutely no different than snails except that they’re lacking a protective exterior shell. Just like snails, slugs are an invertebrate gastropod more closely related to clams, mollusks, and mussels rather than arthropods such as legged insects, spiders, or even centipedes.

Slugs represent some of the most widespread and problematic pests in the garden known for aggressive feeding on nearly any fruit or vegetable. Slugs found in the garden are generally brown to gray and 1-2” long while slugs in the wild can be much bigger and more colorful.

Although slugs may seem more vulnerable than snails because they lack a protective shell, they are often considered more problematic than snails because they are able to hide more thoroughly and reach more potential sources of food without the hindrance of a shell.

How to Get Rid of Slugs

  • Slug Distribution: Slugs are naturalized to just about everywhere in the world
  • Slug Host Plants: Leafy greens including lettuces, brassicas, spinach, and fruiting crops
  • Slug Damage: Aggressively chewed leaves and vegetation similar to grasshoppers
  • Slug Life Cycle: 2-3 years
  • Slug Eggs Per Lifetime: ~400 per year
  • Slug Control: Diatomaceous earth, beer trap, eggshells, salt water, vinegar spray, removal by hand
  • Slug Predators: Birds, beetles, rodents, snakes
  • Most Common Slug in North America: Leopard Slug (Limax maximus)
Leopard Slug Limax maximus
Leopard Slug (Limax maximus)

What Do Slugs Look Like?

The most obvious difference between snails and slugs is that slugs do not have the familiar mollusk-like shell of snails, despite there being no real difference between the two.

Slugs often have more unique coloring and pattern variation than snails, largely because their bodies are not encased in a protective shell and can be more easily seen with the naked eye.

Slugs are popularly found in a wide range of colors throughout the world including red, blue, yellow, orange, black, white, leopard, as well as the more familiar gray and brown. Regardless of environment, slugs are easily recognizable from their two front tentacles.

Slug Damage

Slug Damage
Leaf damage caused by slugs and snails

Damage to plants from slugs and snails can look very similar to the damage caused by grasshoppers and earwigs because they each are plenty big enough to feed on the plant directly.

If suspicious of a slug or snail in your garden bed, look closely for a silvery residue left behind from the snail or slug, sometimes called a snail trail. This silvery streak is fairly noticeable even after it’s dried a little and turned iridescent in the sunlight.

If possible, check the chew marks on your damaged plant for clues because neither slugs or snails eat the veins or smaller secondary veins like grasshoppers.

Slugs isolate the softest, most advantageous parts of the leaf but don’t quite “skeletonize” their host plant like the Japanese beetle.

What Do Slugs Eat?

As mentioned, slugs and snails are no different from one another and, hence, share the same appetites. Slugs feed on tender leafy greens and even softer, tender sprouts and seedlings as they are not picky about what’s in your garden, especially if it’s young and tender.

Snail and slug diets are extremely diverse because they have evolved to consume nearly anything as they’re both omnivores and detritivores, subsisting on decaying organic matter, waste, and other decomposed slugs as readily as they do from leafy greens in your garden bed.

Watch your garden bed closely to learn which greens snails and slugs prefer in your region.

Slug Eggs

Slugs are not as quick to reproduce as other garden pests because snails do not live and die within a single season and may even take up to five years for some species to reach maturity before producing eggs.

However, once they reach sexual maturity, slugs are hermaphroditic, containing male and female organs, and able to reproduce with every other snail.

Slugs lay about 70-80 eggs at a time and keep them protected in damp and shallow crevices to avoid dehydration and detection.

Slug Eggs
Leopard slug eggs in damp foliage

How to Get Rid of Slugs

The three most effective and popular means of ridding the garden of slugs is to either simply remove them by hand, add diatomaceous earth to your garden, or create a beer trap.

Most home gardeners are more than familiar as to the importance of adding razor sharp eggshells and diatomaceous earth to your soil to deter slugs, but few have experienced the immediate benefits of a beer trap. One small saucer of beer placed in the garden can lure dozens of slugs and snails in just hours as they are helpless against the fresh scent of yeast.

Try it once and experience the immediate results for yourself.

Garden Slugs Treatment

How to Get Rid of Slugs
Sprays and solutions for slugs and snails

  • Diatomaceous Earth - One of the most effective treatments for caterpillars, slugs, and snails
  • Slug Beer Trap - Fill a small tray or dish with beer and place in the garden
  • Salt Water Spray - Dilute 1-2 tbsp salt and spray directly onto slugs
  • DIY Vinegar Spray - 1 part vinegar to 3 parts water
  • Eggshells - Similar to diatomaceous earth, but decomposes much faster
  • Coffee Grounds - Add caffeine-rich coffee grounds into your garden soil
  • Removal By Hand - Slugs are not a swarming species and can be individually removed by hand
True leaf divider
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