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Household Ants

Tapinoma sessile and Tetramorium caespitum

Updated Jul 08, 2022

Make a Positive Identification

In the Pacific Northwest, the most common household ants are odorous house ants (Tapinoma sessile) and pavement ants (Tetramorium caespitum).
Ants are social insects that live in nests. They most often build their nests outdoors but sometimes indoors.
They enter buildings in search of food and moisture or to escape extreme weather or flooded conditions.

Odorous House Ants

Species: Odorous House Ants

Odorous house ant with one node highlighted

Eli Sarnat, Antkey, USDA APHIS PPQ, Bugwood.org

Odorous house ants are 1/8-inch long. They are dark brown to shiny black. When crushed, they emit a strong odor. Odorous house ants have one node between their thorax and abdomen, as highlighted in the white box in the photo. Use a magnifying glass or phone app to see this structure.

Species: Odorous House Ants

Mohammed El Damir, Bugwood.org

Odorous house ants nest in shallow mounds in soil and under rocks and wood. The white box in the photo highlights an odorous ant nest. Odorous house ants also sometimes nest indoors in wall gaps or warm places around heaters or water pipes.

Pavement Ants

Species: Pavement Ants

Eli Sarnat, Antkey, USDA APHIS PPQ, Bugwood.org

Pavement ants are 3/16-inch long. They are dark-brown to black. Pavement ants have two nodes between their thorax and abdomen, as highlighted in the white box in the photo. Use a magnifying glass or phone app to see this structure.

Species: Pavement Ants

Joseph Berger, Bugwood.org

Pavement ants nest under rocks, boards, and patios. They also nest along foundations or near water. The photo shows many pavement ants on a patio made with pavers.

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Look-Alike: Carpenter Ants

Species: Look-Alike: Carpenter Ants

Outdoor wood in landscape with carpenter ant wood dust piles

Edward H. Holsten, USDA Forest Service, Bugwood.org

Carpenter ants (Camponotus spp.) build nests outdoors in tree stumps, firewood, fence posts, and wooden retaining walls.

They also build nests indoors within intact, dry wood, or water-damaged wood, insulation, crawl spaces, and attic spaces.
Piles of wood dust as shown in the photo are signs of carpenter ant activity.
Carpenter ants are about 1/4 to 5/8 inches long. They are either black, red, or a combination of these two colors.

Different risks or methods

Take action to control carpenter ants for homes and structures. Tolerate them away from structures. They are part of the natural environment.

How to Get Rid of Carpenter Ants

Household Ants Benefits

Ants are part of the natural environment. They help recycle dead animals. Other animals eat ants.

Household Ants Risks

They enter buildings in search of food and moisture or to escape extreme weather or flooded conditions.
Household ants are a nuisance and can ruin food.

Risk Card

Does it cause harm?

Adults & Children

Low

Property

Some

Pets

Low

Annoyance

Very High

Environment

Helpful

Action Recommended

Take Action

Avoid encouraging ants by cleaning up food and garbage/recycling that attracts them. Use soapy water to wipe up ants when you see them in your home. Use ant baits as needed for indoor ant problems.

Do I need to take action?
Yes. Ant trails need to be cleaned.

What if I do nothing?
More ants will be attracted to the food source. It will take longer to clean up the mess.

Prevent Household Ants

Michael Merchant, Texas Cooperative Extension, Bugwood.org

Don’t Attract Ants and Clean Up Foraging Ants

Follow the steps detailed above to prevent household ant problems.

Use Baits as Needed

Ant populations are just beginning to grow in late winter and early spring. Placing ant bait at this time is an effective way to control ant colonies.
The photo shows odorous house ants attracted to the food in a bait station.

SOLUTIONS FOR HOUSEHOLD ANTS

Keep Ants Out of Your Home

Fix moisture problems that attract ants into structures.
Seal your buildings to keep ants out.

Remove Ant Food Sources

Clean up food that attracts ants, including sweets, sugar, pet food, grease, and protein.
Dispose of your garbage and recycling regularly. Unrinsed drink cans and food containers attract foraging ants.
Store food that attracts ants in sealed containers with a tight-fitting lid.

Monitor and Take Action as Needed

Watch for foraging ants. Wipe them up with soapy water and a sponge. Get rid of them before they return to the nest and bring back more ants.
Watch for ants on indoor plants. Aphids and other insects feed on plants, which creates honeydew that attracts ants.
Ant bait products effectively kill ant colonies. Follow the instructions for best results.

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.

Method	Does it work?	Is it safe?	Recommendation
A Clean Up Foraging Ants With Soapy Water	Effective	Low risk	Recommended
B Ant Bait Products	Very effective	Low risk	Recommended
C Insecticide Sprays	Effective	Moderate risk	Use if Necessary
D If Using Insecticides, Protect Yourself & Minimize Risks

Clean Up Foraging Ants With Soapy Water

Non-Chemical Method

Varvara Kalashnikova, iStock

Clean Up Foraging Ants With Soapy Water

Recommended

Use sponge with soapy water to clean up ants and their trails.
Cleaning up foraging ants keeps them from returning to the nest and drawing more ants.

Does it work?	Effective Cleaning up ant messes is a required step. Use preventive measures for best results.
How much effort?	Moderate effort
What's the risk?	Low risk
Possible risk of exposure or harm from chemicals	NONE

Ant Bait Products

Chemical Method: Use with caution

Weston Miller, Oregon State University

Ant Bait Products

Recommended

Ants take bait back to their nest. The bait poisons the nest, and eliminates the colony.
Product labels indicate whether they are for use indoors or outdoors. Choose the right product for your application. The product in the photo is intended for use outdoors only.

Does it work?	Very effective It may take several weeks for ant baits work. Use preventive measures for best results.
How much effort?	Low effort
What's the risk?	Low risk Insecticides come with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know.
Possible risk of exposure or harm from chemicals	Using insecticides includes some amount of risk. The lowest risk comes with using alternative methods. You may be exposed to an insecticide if you: Get it on your skin Breathe it in Eat or smoke afterward without washing hands Touch surfaces that are wet with spray (you, pets, or children) Follow directions closely to reduce risk.

Ant baits include a food source and insecticide(s).
Foraging ants take the bait back to the nest. The ants transfer the bait among workers, larvae, and queens.
Follow the product label instructions to minimize the risks and maximize the benefits.

Ant bait package with active ingredient borax

NoDerog, iStock

The photo shows the package of a ready-to-use ant bait product. It has a plastic bait station to keep the bait away from children and pets. The white box in the photo highlights the active ingredient, borax. Text in the other white box states “Kills All Common Household Ants.”

Weston Miller, Oregon State University

This photo shows the package of ready-to-use ant bait stakes for outdoor use. The white box in the photo highlights the active ingredient, indoxacarb. Text in the other white box states “Kills the Queen & DESTROYS THE COLONY.”

Ant Bait Details

The food source for ant baits includes sweets and/or proteins.
Ants are attracted to varying food sources throughout the year.
To increase your chances of success, place several different types of bait at one time. This method gives ants a choice, depending on their food preference.
Ant populations are just beginning to grow in late winter and early spring. Placing ant bait at this time is an effective way to control ant colonies.

Insecticide Sprays

Chemical Method: Use with caution

Weston Miller, Oregon State University

Insecticide Sprays

Use if Necessary

Insecticide spray products for ants effectively control foraging ants.
You’ll still have to wipe them up with soapy water.

Does it work?	Effective Plant-based insect sprays kill ants on contact. Insecticides in the pyrethroid group kill ants on contact and provide moderate residual activity. Use preventive measures for best results.
How much effort?	Moderate effort Use spray to control foraging ants. You will still have to wipe them up with soapy water.
What's the risk?	Moderate risk Insecticides come with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know.
Possible risk of exposure or harm from chemicals	Using insecticides includes some amount of risk. The lowest risk comes with using alternative methods. You may be exposed to an insecticide if you: Get it on your skin Breathe it in Eat or smoke afterward without washing hands Touch surfaces that are wet with spray (you, pets, or children) Follow directions closely to reduce risk.

We recommend using soap and water to clean ants and ant trails. Soapy water disrupts the scent trail from the food source to the nest.
The insecticides described below kill insects on contact. Some provide moderate residual control. You will still have to wipe up the ants with soap and water after you spray them.
Carefully follow the label instructions to minimize the risks and maximize the benefits.

Weston Miller, Oregon State University

Plant-Based Insect Sprays

Products with plant-based oils as active ingredients kill ants and other insects on contact. They don’t perform any residual insect-killing activity.
Choose products that indicate they are for use around people and pets.
Plant-based oils are formulated in insect-control products. The white box on the product label highlights active ingredients geraniol and lemongrass oil. Both are plant-based ingredients.
The other white box states “SAFE FOR USE AROUND PEOPLE AND PETS When used as directed.”

Pyrethroid insect killer for indoor and perimeter use

Weston Miller, Oregon State University

Pyrethoid Insecticide Sprays

Insecticides in the pyrethroid group are available for treating ants.
The product label in the photo says “INSECT KILLER FOR INDOOR + PERIMETERS” and “USE INSIDE AND OUTSIDE YOUR HOME!”
These products kill ants on contact. They also provide about 1–4 weeks of residual activity to keep ants away under outdoor conditions.
However, they can flow off walls and foundations and make their way into storm drains and then waterways. Pyrethroid insecticides are extremely toxic to fish and aquatic invertebrates.

More about Pyrethroid Active Ingredients

Pyrethroid insecticides include the following active ingredients: bifenthrin, cyfluthrin, esfenvalerate, gamma-cyhalothrin, lambda-cyhalothrin, and permethrin.

If Using Insecticides, Protect Yourself & Minimize Risks

Chemical Method: Use with Caution

staticnak1983, iStock

Why Is It Important to Read Insecticide 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.

Key Safety Tips for Insecticides

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 can be applied.

The Label is the Law

ALWAYS read the label before using insecticide products. The label is a legal document that provides information on how to safely use the insecticide. This helps avoid harm to human health and the environment. Using an insecticide 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 insecticide 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.

Protect Children & Pets
Keep out of the reach of children.

Keep children and pets away from the application area.
Remove toys and pet dishes from the area before applying insecticides. Wait until spray has dried or dust has settled.

Avoid Wet Weather & Keep Insecticides Out of Waterways
Some insecticides are toxic to fish and aquatic invertebrates.

Don’t spray insecticides in water.
Insecticides sprayed on the exterior of your home can wash off with rain and enter waterways.

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 insecticides 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

Content provided by editor Weston Miller and writer J. Jeremiah Mann. Pesticide safety information edited by Kaci Buhl.

Reviewed by OSU Department of Horticulture.

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:

J. Jeremiah Mann

J. Jeremiah Mann completed a Physical Science undergraduate degree at Humboldt State University, and M.S, Ph.D focusing on plant science topics at UC Davis. He went on to work for the Natural Resources Conservation Service and in a leadership position serving a private agricultural technology company. He currently lives in Sacramento California where he consults on pest and property management topics.

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.

HOUSEHOLD ANT REFERENCES

Ants
University of California IPM

Ants in the Home
Colorado State University

Solve Pest Problems

Household Ants

Make a Positive Identification

Household Ants Benefits

Household Ants Risks

Take Action