WSU Extension

Pestsense

Nuisance
 
Bagworms
Brown marmorated stink bug
Centipedes
Clover mites
Cluster flies
Cockroaches
Firebrats
Fruit flies
Fungus gnats
Giant house spider
Hobo spider
House centipede
House dust mites
House flies
Little house flies
Mice and rats
Millipedes
Moth flies (drain flies)
Multi-colored Asian lady beetle
Odorous house ants
Pavement ants
Pseudoscorpions
Root weevils
Seed bugs
Silverfish
Sowbugs and pillbugs
Spiders (non-biting)
Springtails
Thatching ants
Western boxelder bug



print version| pdf version| email url    
Caption: Odorous house ant
Photo by: Susan Ellis
  
Odorous house ants
(revision date: 3/15/2019)

Use Integrated Pest Management (IPM) for successful pest management.

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. They 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

Non-Chemical Management
  • 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.
Select non-chemical management options as your first choice!

Chemical Management

Try to find the nest if possible. This should be done at night with 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.

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.
  • Combat MAX Ant Killing Gel
    Active ingredient: fipronil  |  EPA reg no: 64240-42
  • Combat Outdoor Ant Killing Granules
    Active ingredient: hydramethylnon  |  EPA reg no: 64240-25
  • Amdro Kills Ants Ant Killing Bait
    Active ingredient: hydramethylnon  |  EPA reg no: 1663-33-73342
  • Bonide Termite & Carpenter Ant Killer Conc
    Active ingredient: permethrin  |  EPA reg no: 4-349
  • Revenge Liquid Ant Bait
    Active ingredient: boric acid  |  EPA reg no: 4-424
  • Terro Ant Killer II Liquid Ant Baits
    Active ingredient: sodium borate  |  EPA reg no: 149-8
  • Raid Double Control Ant Baits II
    Active ingredient: abamectin  |  EPA reg no: 4822-472
  • Raid Max Double Control Ant Baits
    Active ingredient: abamectin  |  EPA reg no: 4822-472
  • Orthro Bug B Gon Insect Killer/Lawns and Gardens R-T-Spray
    Active ingredient: Bifenthrin, Zeta-cypermethrin  |  EPA reg no: 279-9535-239
  • This list may not include all products registered for this use.
Images

+ Show larger images

 
Caption: Odorous house ant
Photo by: Susan Ellis