If you’ve crushed a small dark ant on your Boise kitchen counter and noticed a smell like rotten coconut, you’ve met the odorous house ant. It’s one of the most common ants inside homes in the Treasure Valley, and it’s especially fond of kitchens, where sweets, crumbs and moisture are all close together.
Odorous house ants don’t damage wood or sting, but they can show up in large numbers, contaminate food and come back again and again if the colony isn’t dealt with. Here’s how to recognize them, why they target kitchens and what actually helps.
How to Recognize Odorous House Ants
- Size and color. Small, about one-eighth of an inch, and dark brown to black.
- The smell. A strong rotten-coconut or sour odor when crushed.
- Behavior. Fast, erratic movement along well-defined trails, often along counter edges, baseboards and pipes.
- Colonies. Colonies can have many queens and split into several nests, which is why they’re hard to get rid of with spot treatments.
Not sure which ant you have? Our ant identification guide compares the species we see most in the valley. Pavement ants, for example, are similar in size but usually nest under concrete. Our post on getting rid of pavement ants covers those.
Why They Head for the Kitchen
Odorous house ants feed mostly on sweets, and they also collect honeydew outdoors from aphids on shrubs and trees. In a kitchen, they find spilled juice, sugar, fruit, crumbs, pet food and grease. They also need water, so sinks, dishwashers and leaky supply lines draw them in.
In Boise, kitchen invasions often spike in spring and after summer rains, when outdoor nests are disturbed or flooded by irrigation, and again in fall when honeydew sources dry up.
Where They Come From
Most odorous house ant colonies nest outside, under mulch, stones, landscape timbers and debris near the foundation. Workers trail into the house through cracks in the foundation, gaps around windows and doors, and openings where pipes and wires enter. Some colonies move inside and nest in wall voids, under floors or behind cabinets near moisture.
Clean Up What Attracts Them
- Wipe counters, tables and stovetops each evening, and sweep crumbs from floors.
- Store sugar, cereal, honey and snacks in containers with tight seals.
- Rinse recyclables and keep a lid on the trash.
- Pick up pet food between meals and wipe up spills around the bowl.
- Fix dripping faucets and leaks under the sink, and don’t leave sponges sitting wet.
When you find a trail, wipe it with soapy water. That removes some of the scent the ants use to follow each other, but it won’t eliminate the colony.
Block the Ways In
- Caulk gaps around windows, door frames and where pipes and wires come through walls.
- Repair door sweeps and weatherstripping.
- Trim shrubs and tree branches so they don’t touch the house.
- Pull mulch back from the foundation and keep firewood, stones and debris away from the walls.
Why Sprays Often Make It Worse
Spraying a trail with a store-bought insecticide kills the ants you see, but the colony stays put and other workers keep coming. With odorous house ants, repellent sprays can even cause colonies to split into new nests. The better approach is to find where the ants are nesting and treat the colony, which a professional typically does with targeted gel bait indoors and non-repellent treatments outside. Gel baits work slowly because workers carry them back to share with the rest of the colony.
Penn State Extension’s fact sheet on odorous house ants has more detail on their biology and control.
When to Call for Help
If trails keep coming back after cleaning and sealing, if you’re seeing ants in several rooms or if you suspect a nest inside the walls, a professional treatment can reach the colony. Our post on ant prevention in the kitchen has more tips for keeping ants out once they’re under control.
Ants are part of our residential pest control, along with spiders, wasps and hornets, mice, rats and fall invaders. We offer quarterly, bi-annual and one-time service. Quarterly service plan customers get free return visits. No contracts; cancel with 30 days’ notice. We also treat restaurant kitchens, break rooms and other commercial properties in Boise.
Odorous House Ant FAQs
Why do odorous house ants smell when crushed?
They give off a chemical when they’re crushed or disturbed. Many people describe it as a rotten-coconut or sour smell, and it’s one of the easiest ways to tell them apart from other small, dark ants.
Why do they show up after it rains?
Heavy rain or irrigation can flood outdoor nests, and the colony moves to drier ground. Sometimes that’s inside a wall or under the kitchen floor. Hot, dry weather can push them indoors looking for water, too.
If I kill the ants I see, will they stop coming?
Usually not. The ants on the counter are foragers. The colony, with its queens, stays hidden, and odorous house ant colonies can have many queens and several nest sites, so more foragers keep coming.
Ants in Your Kitchen?
ProGuard is based in Eagle and serves homes and businesses in Boise, Meridian, Nampa, Caldwell, Star, Middleton, Emmett and Garden City. Call (208) 352-2062 or contact us to schedule an inspection and get your kitchen back.