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Slugs & Snails

Non-native & native species in the Pacific Northwest
Updated Feb 22, 2023
 
1

Make a Positive Identification

Slug & Snail Damage

  • Slugs and snails are mollusks. They cause feeding damage to a wide range of plants and leave slime trails. They are mostly active at night. They also feed during the day when it is overcast, cool, and damp.
  • You’ll probably notice signs of damage to plants before you see actual slugs and snails.

Non-native Slugs & Snails

Non-native slugs and snails cause feeding damage on a variety of plants in gardens, landscapes, and farms in the Pacific Northwest.

Native Slugs & Snail

Many species of native slugs and snails, such as banana slugs, are a key part of the natural environment. Native slugs and snails are generally not garden pests and may be left alone.

Slug & Snail Damage & Signs
Species: Damage
Hosta leaf with many holes

Robin Rosetta, Oregon State University

Slugs and snails damage leaves by scraping or shredding them, and making ragged holes.

Species: Damage
Severe slug damage to brassica seedlings

svehlik, iStock

Slugs and snails may completely eat seedlings and the growing points of young plants. Severe damage may result in plant death or slow growth.

Species: Damage
Slug and damage on strawberry

Akchamczuk, iStock

Slugs and snails scrape holes in fruits such as tomatoes and strawberries.

Species: Damage
Slug eating a carrot

Signe Danler, Oregon State University

Some slugs spend more time underground and often feed on roots and tubers. They leave shallow or deep smooth-sided pits.

Species: Slime Trails
Trails of slime on wooden surface

Slugs and snails leave silvery slime trails on plants and other surfaces. They may also leave small sausage-shaped feces.

Non-Native Slugs & Snails
Species: Gray garden slugs
Gray garden slug

Cheryl Moorehead, Bugwood.org

Gray garden slugs (Deroceras reticulatum) are the most common garden pest slug in Oregon. They are also known as gray field slugs. They grow to 1.4–2 inches long.

Species: Threeband Garden Slug
Threeband garden slug

Rebekah D. Wallace, University of Georgia, Bugwood.org

The threeband garden slug (Ambigolimax valentianus) is another common slug in gardens and public parks in Oregon. They have 2–3 dark-colored lines running the length of the body as shown in the photo.

Species: Giant garden slugs
Giant garden slug (Limax maximus)

Giant garden slugs (Limax maximus) are widespread in Oregon. They have spots on their body as shown in the photo. They grow up to 4 inches long.

Species: Brown snails
Brown snail on leaf

Joseph Berger, Bugwood.org

Brown garden snails (Cornu aspersum) are the most common snail garden pest in Oregon. Their shell diameter ranges from 1–1.5 inches wide.

Species: European black or red slugs
Gary Bernon, USDA APHIS, Bugwood.org

Gary Bernon, USDA APHIS, Bugwood.org

European black or red slugs (Arion rufus) are widespread in Oregon. They have a reddish, orange, brown, or black color and grow to 2.75–4 inches long.

Species: Brown-banded Arion Slug
Brown-banded Arion

Brown-banded Arion slugs (Arion circumscriptus) have brown stripes on their back. They grow to less than 1.75 inches long.

Species: Glass snails
Glass snail

Michal Maňas, CC BY 4.0, via Wikimedia Commons

Glass snails (Oxychilus spp.) are present throughout Oregon. One species of glass snail (O. alliarus) emits a garlic odor when crushed. Their shell grows to 0.2–0.6 inches in diameter.

LOOK-ALIKES: NATIVE SLUGS & SNAILS
Species: Banana slugs
Banana slug

Thomas Schoch, CC BY-SA 2.5, via Wikimedia Commons

The Pacific banana slug (Ariolimax columbianus) is a common, native species in Western Oregon. Its color ranges from yellow, green, and gray to reddish brown, and even white. It also occurs with and without spots. Banana slugs grow from 7–10.2 inches long.

Tolerate if possible

Banana slugs live in forested areas. They don’t cause damage to garden plants. You may leave them alone.

Species: Pacific sideband snails
Pacific sideband snail

Pacific sideband snails (Monadenia fidelis) often have distinct, dark stripes. Their shell grows from 0.7–1.5 inches in diameter.

Tolerate if possible

Pacific sideband snails live in forested areas. They don’t cause damage to garden plants. You may leave them alone.

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2

Slugs & Snails Benefits

  • Slugs and snails provide food for insects, birds, reptiles, amphibians, mammals, and other predators.
 

Slugs & Snails Risks

  • Slugs and snails damage plants and make them look tattered.
  • They can eat young plants to the ground and make crops such as strawberries unusable.
  • Slugs and snails have also been implicated in the spread of plant diseases and human pathogens.
Risk Card
Does it cause harm?
Adults & Children
None
Property
Low
Pets
None
Annoyance
Some
Environment
Low
Action Optional
 
3

Take Action?

Take action to protect vegetable crops, strawberries, and ornamental crops if you can’t tolerate the damage.

Do I need to take action?

  • You may ignore minor slug and snail damage. But damage may get worse as the population grows.
  • Slug and snail damage to small seedlings can be severe and lead to a complete loss. You may have to start over and suffer some economic loss.

What if I do nothing?
The damage may get worse as the population grows.

 
4

Prevent Slugs & Snails

Worker checking nursery plants

AJ_Watt, iStock

Check New Plants Before Bringing Them to Your Site
  • Slugs and snails hitchhike in planting containers to new locations.
  • Before you bring new plant containers onto your site, perform a thorough check to make sure there aren’t any slugs, snails, or their eggs.
Fern frond with no slug damage even in shade

Signe Danler, Oregon State University

Choose Resistant Plants
  • Choose plants that are not attractive to slugs and snails. Generally, they avoid plants with scented foliage, including sage, rosemary, and lavender.
  • They also avoid plants with tough foliage, such as ferns, bamboo, Sedum (stonecrop), heavenly bamboo (Nandina), cyclamen, hydrangea, and conifers.
  • Slugs and snails favor many vegetable crops and fruits such as strawberries. They also damage many landscape plants such as dahlias, delphinium, hosta, daffodils, and lilies.
Slug and slug eggs

Weston Miller, Oregon State University

Minimize Hiding Places
  • Turn over winter mulch to expose slugs, snails, and their eggs to predators. This step also facilitates hand picking.
  • Remove garden objects (such as rocks and boards), plants, or ground cover that slugs and snails shelter under (except as traps).
  • Place vegetable gardens or susceptible plants as far away from snail and slug hiding areas as possible.
Drip irrigation confines moisture, discourages slugs and snails

Signe Danler, Oregon State University

Control Watering
  • Drip irrigation (shown in photo) limits humidity and moist surfaces compared to overhead watering. These drier conditions make the habitat less favorable for slugs and snails.
  • Water early in the morning to allow more time for plants to dry. Evening is when slugs and snails come out to eat.
Copper tape on planting container

Weston Miller, Oregon State University

Use Barriers
  • A band of copper tape placed around containers and raised beds can deter slugs and snails.
  • Diatomaceous earth placed in a band 1 inch high and 3 inches wide around the garden can slow mollusks down. It is not effective after it becomes wet.
Small cultivator in vegetable garden

"Mantis Tiller" by David Goose / MSI is licensed under CC BY-NC-SA 2.0 (cropped).

Cultivate Soil
  • Cultivation (turning soil over) can kill slugs and their eggs directly and expose them to predators.
  • However, too much cultivation can harm soil structure and lead to erosion.

 

 
5
Solutions for Slugs & Snails

For best results to control slugs and snails, use a combination of methods.

Monitoring & Timing

  • Look for slugs and snails at night with a flashlight and/or under planting containers, boards, rocks, and debris.
  • Control efforts in the fall and early spring will lower their numbers through the course of the growing season.

Non-chemical Methods

  • Remove slug and snail hiding places such as under planting containers, rocks, and boards.
  • Encourage slug and snail predators such as ground beetles, amphibians, and snakes. See Biological Pest Control Methods.
  • Hand-pick slugs and snails and drop them into a container with soapy water.
  • Use beer (or a mixture of flour, water, and yeast) and board traps to capture them.

Molluscicides (Mollusk-Killing Chemicals)

Molluscicides effectively reduce slug and snail populations. They don’t eliminate them.

NEED HELP?

Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon  and other states  can suggest other methods.

Jump to

Method Does it work? Is it safe? Recommendation
A
Attract Slug & Snail Predators
Somewhat effective
Low risk
Recommended
B
Monitoring, Hand Picking & Trapping
Effective
Low risk
Recommended
C
Molluscicides
Effective
Moderate risk
Use if Necessary
D
If Using Molluscicides, Protect Yourself & Minimize Risks
 
A

Attract Slug & Snail Predators

Non-Chemical Method

"015_garter_snake_coiled_nwwd_odfw" by Oregon Department of Fish & Wildlife is licensed under CC BY-SA 2.0.

Attract Slug & Snail Predators

Recommended

Many vertebrates eat slugs and snails, including wildlife (birds, snakes, and frogs) and domestic animals (ducks). Spiders and beetles also prey on slugs and snails. Encourage those predators that fit with your gardening approach.

Does it work?
Somewhat effective
  • Predators work to reduce slug and snail populations. They won’t eliminate slugs and snails. Use with other methods.
  • Use preventive measures for best results.
How much effort?
Low effort

Provide habitat for wildlife such as garter snakes (shown in photo) and soil-dwelling insects such as predatory ground beetles.
What's the risk?
Low risk
Possible risk of exposure or harm from chemicals
NONE
Predatory ground beetle eating a small slug

Ground-dwelling spiders and invertebrates such as beetles (shown in photo), larvae of certain flies, centipedes, millipedes, and other snails eat slugs and snails and their eggs.

Domestic duck

Copyright-free from piqsels.com

Domestic ducks eat slugs and snails. Be careful about allowing ducks in your garden. They will eat seeds and seedlings. They will also eat established plants if left too long in one location. Also, ducks pose a risk in terms of food safety for crops that grow low to the ground, such as lettuce and strawberries.

 
B

Monitoring, Hand Picking & Trapping

Non-Chemical Method

Signe Danler, Oregon State University

Monitoring, Hand Picking & Trapping

Recommended

Use these non-chemical slug methods to reduce slug and snail damage on and near plants you want to keep from being damaged.

Does it work?
Effective
  • Monitoring, hand picking, and trapping methods work to reduce slug and snail populations. They won’t eliminate slugs and snails. Use with other methods.
  • Use preventive measures for best results.
How much effort?
Moderate effort

Monitor, hand pick, and set/clean traps repeatedly.
What's the risk?
Low risk
Possible risk of exposure or harm from chemicals
NONE
Worker monitoring for slugs at night with a flash light

Slug & Snail Monitoring

  • Begin monitoring for slugs in early spring. Continue through fall.
  • Water in the late afternoon to draw out snails and slugs. After dark, search them out using a flashlight.
  • Put out slug bait in late afternoon. Return early the next morning to check for dead slugs and snails.

 

Gloved hand holding slug

beekeepx, iStock

Hand Picking

  • Hand-picking slugs and snails can be very effective if done regularly. Look in hiding places such as under rocks and foliage.
  • Wear rubber or latex gloves to pick them up, or use tongs. Seal the pests in a plastic bag and dispose of them in the trash. Or drop them in a bucket of soapy water (shown in photo).
Slug and egg cluster

Search for Slug and Snail Eggs

  • Slugs and snails lay their eggs (shown in the photo) in the late summer and fall.
  • Search for slugs and snails and their eggs at this time of year. Dispose of them as previously described.
  • Removing egg clusters reduces the population of slugs and snails.
Slug and snail trap: yogurt container with hole cut in side, filled with beer

Signe Danler, Oregon State University

Trapping

  • Place flat boards or upside-down flower pots with one edge propped up around the garden. Slugs and snails will hide under them and may be collected.
  • Other traps use beer or a mixture of flour, water, and yeast in a deep yogurt container (or similar). Place the rim at ground level. Slugs and snails get trapped in the liquid in the container
  • Check traps and destroy pests regularly.
 
C

Molluscicides

Chemical Method: Use with caution

Weston Miller, Oregon State University

Molluscicides

Use if Necessary

Bait products with active ingredients iron phosphate, ferric sodium EDTA, and metaldehyde reduce slug and snail populations, but will not eliminate them. Metaldeyde can harm other organisms.

Does it work?
Effective
How much effort?
Moderate effort

Place baits near plants you want to protect. Re-apply as directed on the label.
What's the risk?
Moderate risk

Molluscicides come with real risks. ALWAYS read the entire label front to back. Use a magnifying glass.
Possible risk of exposure or harm from chemicals
El uso de pesticidas conlleva cierto grado de riesgo. El riesgo más bajo se produce sin el uso de pesticidas.

You may be exposed to a pesticide if you:

  • Get it on your skin
  • Breathe it in
  • Eat or smoke afterward without washing hands
  • Touch or eat plants that are wet with spray (you, pets, or children)
  • Bring it inside on your shoes or clothes

Follow directions closely to reduce risk.

Molluscicides contain active ingredients iron phosphate, ferric sodium EDTA, and metaldehyde. Determine which ingredient is right for your situation.

Example product label with active ingredient iron phosphate

Weston Miller, Oregon State University

Iron Phosphate (Approved for Organic Farming)

  • The white box on the example product label highlights the active ingredient iron phosphate.
  • Iron phosphate causes snails and slugs to stop feeding and die within 3 to 6 days.
  • Iron phosphate remains active for up to 2 weeks, even after it gets wet.
  • It’s considered safe to use around pets, humans, fish, birds, beneficial insects, and mammals. It may be used around food crops and ornamental plants.
Example product label with active ingredient ferric sodium EDTA

Weston Miller, Oregon State University

Ferric Sodium EDTA

  • The white box on the example product label highlights active ingredient ferric sodium. The label states “Attracts and kills slugs and snails."
  • Ferric sodium EDTA is a newer active ingredient that works similar to iron phosphate.
  • Products with ferric sodium EDTA aren’t approved for use in organic farming.
Example product label with active ingredient metaldehyde

Metaldehyde

  • The white box on this example product label highlights active ingredient metaldehyde.
  • Metaldehyde destroys the mucus-producing system so snails and slugs dehydrate from exposure to the sun.
  • If it rains soon after application, this may not work.
  • Metaldehyde is not recommended for use around edible vegetables.
Metaldehyde is toxic to people, dogs, cats, birds, and fish. Read and follow the label instructions carefully.

MolluSCICIDE Application Tips

Placement of baits

  • Scatter baits on the soil near the base of plants that are prone to slug and snail damage.
  • Apply the bait close to slug and snail hiding places such as raised bed sides, rock walls, pavers, and fences.
  • Apply repeatedly in the same areas. Check the product label to ensure it can be reapplied in the same area.
  • Irrigate before baiting in home gardens in order to bring more slugs to the surface or out of hiding during the night.

Timing of baits

  • Apply baits in the late afternoon or evening. This takes advantage of the pests’ nighttime feeding habits.
  • The best time to treat the whole garden for long-term control is in the autumn. Then, there will be fewer adult slugs and snails to lay their eggs.
  • Baits are most effective in moist weather and moderate temperatures. Slugs are less active in hot, cold, dry, or extremely wet conditions.

Limitations

  • Molluscicide baits will not be very effective unless you also remove shelter and moisture. Slugs that survive poisoning by baits tend to avoid the baits in the future.

Alternative Chemical Options

Alternative chemical options include certain botanical products such as limonene and repellent botanical products such as cinnamon oil.

 

If Using Molluscicides, Protect Yourself & Minimize Risks

Chemical Method: Use with Caution
Dog digging in garden

ChristopherBernard, iStock

Metaldehyde baits are a leading cause of accidental poisoning of dogs in the Pacific Northwest.

Why Is It important to Read Molluscicide Labels?

  • They have detailed information on how to use the product correctly and legally.
  • They contain information on potential hazards of the product.
  • They provide instructions you should follow for poisonings and spills.
  • Following label instructions helps you to minimize the risks and maximize the benefits.

Key Safety Tips

  • Read the entire label front to back.
  • Follow the instructions.
  • Review the instructions even for brands you know.
  • Only apply the product where the label says it may be applied.
  • Keep all molluscicides in their original container.

The Label is the Law

ALWAYS read the label before using molluscicide products. The label is a legal document that provides information on how to safely use the molluscicide. This helps avoid harm to human health and the environment. Using a molluscicide in off-label ways is illegal. It can result in legal enforcement actions.

READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.

  • Labels are different for every product and they often change over time.
  • Use a magnifying glass for small print.
  • Pay attention to CAUTION, WARNING, and DANGER statements.
  • Pay attention to the PRECAUTIONARY STATEMENTS.
  • The law states you must read and follow molluscicide instructions.

Protect Yourself
Eye, skin, & lung irritants

  • Wear gloves, safety glasses, a long-sleeve shirt, pants, socks, and shoes.
  • Avoid contact with eyes, skin, or clothing.
  • Wash hands after mixing or applying, and before eating or smoking.
  • Never spray directly overhead. Pay attention to wind conditions.

Protect Children, Pets, Domestic Animals & Wildlife
Children, pets, and wildlife are at risk if they touch or consume metaldehyde-based slug control products.

  • Keep molluscicides out of reach from children and pets at all times.
  • Dogs, cats, and wildlife are also attracted to and harmed by metaldehyde.
  • Apply slug and snail baits under a piece of plywood, or something similar, to keep pets away from the pellets.

Storage & Disposal

  • Store out of the reach of children and pets.
  • Store in a cool and dry place.
  • Never pour down any drain.
  • If you mix too much, apply it rather than storing it.
  • Don’t put pesticide containers in the trash unless instructed by the label.
  • Take unused molluscicides to a hazardous waste facility.

Call  1-800-CLEANUP (1-800-253-2687) to find out where to dispose of pesticides.

For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call  503-234-3000, email   or visit Metro’s website  

More about:

About Using Pesticides on School Grounds in Oregon

If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management  (Oregon Department of Agriculture).

NEED HELP?

The National Pesticide Information Center (NPIC)  can answer questions about pest control chemicals.
 1-800-858-7378 or npic@ace.orst.edu  

Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.

Your local Extension Specialist in Oregon  and other states  can suggest other methods.

SEE OTHER COMMON PACIFIC NORTHWEST INSECTS, SLUGS & DISEASES ON PLANTS

Content provided by writer Signe Danler and editor Weston Miller. Pesticide safety information edited by Kaci Buhl.

Signe Danler

Signe Danler (Editor/Writer)

Signe Danler is a veteran Master Gardener and landscape designer, with an MAg degree in Horticulture from OSU, and an emphasis on Urban Horticulture. As instructor for the OSU Extension Service online Home Horticulture and Master Gardener Program, she uses her experience and training in gardening, urban forestry and ecological landscaping to communicate about and promote sustainable gardening and landscaping practices.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals:

Photo of Kaci Buhl

Kaci Buhl

At the state level, I lead the Pesticide Safety Education Program (PSEP). The program hosts live recertification events around the state, serving over 1,000 licensed pesticide applicators each year. We also produce web-based training modules and license-preparation study manuals. Special training for unlicensed pesticide applicators is also available through a grant from the USDA Specialty Crop Block Grant Program. The PSEP at OSU works closely with the Oregon Department of Agriculture's Pesticides Division.

Slug & Snail References

Slug Control  
PNW Insect Management Handbook

Provisional Management Guidelines  
Slug Portal, Oregon State University

Slugs and Snails in Oregon  (PDF)
Oregon Department of Agriculture

Slugs and Snails  
University of California IPM