Odorous house ants
categories: Fact Sheet Nuisance Pests
revision date: 2025-12-31 01:54
Photo by: Susan Ellis, Bugwood.org
Biology
Odorous house ants are extremely small. Workers are approximately 1/16 inch long and have a uniform brown to black color.
They nest in the soil in shapeless, shallow, and temporary colonies, as these ants frequently move. They feed on a wide variety of things including nectar, honeydew from aphids, and living and dead insects.
These ants easily enter homes where they feed on dairy products, fruit juices and pastry. They are perhaps the most difficult ants in our area to discourage. Swarming occurs throughout the year but most commonly in June and July.
Management Options
Use Integrated Pest Management (IPM) for successful pest management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Prevention of conditions conducive to invasion is the only non-chemical option as these ants send scouts into areas of potential food presence. If kitchens are kept as clean of food and liquid residues as possible, it will help to discourage them from returning.
- Using a sponge and soapy water, wipe-up any ants and their trails that you see.
- Seal all potential entry points. This can be extremely difficult since the ants are small.
- Keep trees and shrubs from touching buildings.
- Keep odorous house ants off landscape plants near buildings.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Try to find the nest if possible.
- Odorous house ants follow trails which are visible after noon, but not necessarily at night. You can use a flashlight to follow the ants using trails from their nest to your home.
- If detected, treat the nest. If the nest cannot be found, treat the area where the foundation and soil meet to form a chemical barrier.
- There are also bait materials you can use indoors.
Approved Pesticides
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.
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