Odorous House Ants

( Tapinoma sessile )


Odorous house ant characteristics

Size: About one-eighth of an inch long.

Color: Brown or black.

Behavior: Odorous house ants may develop huge colonies containing thousands of workers and numerous queens. This species may be difficult to control. And even though Odorous house ants will feed on sweet ant baits, because the colony is so large it's quicker to follow the trails and treat the nest sites directly.

Where Do You Find Odorous House Ants?

Odorous house ants are found throughout the United States, as well as in Canada and Mexico. They are especially common from California through Washington and in the Mid-South region, including Arkansas and West Tennessee. These ants can be found outdoors and often enter structures such as homes and other buildings.

Outdoors, odorous house ants will nest and establish colonies under rocks, boards, logs and in mulch. They are active and forage for food both during the day and at night, and they are primarily visible when temperatures range between 70 and 86 degrees Fahrenheit.

Indoors, these ants establish nests near sources of moisture and warmth. They typically gravitate toward cracks and voids in walls, but they may even nest in wood that's been damaged by termites. Other common places to find them inside include under carpet, around the edge of toilets and in cabinets or drawers. Odorous house ants are more likely to be seen inside after periods of rain.

A few worker ants found inside the home does not necessarily signal an infestation — they may simply be searching for food to return to an outdoor nest. However, winged reproductives of this species typically appear between May and July. If these ants are seen indoors, there is likely a nest somewhere in the home.

Odorous house ants travel in well-established trails that are often visible along the base of buildings, on floorboards or carpet and on trees and sidewalks. These trails connect foraging and feeding sites to the nesting sites.

What Attracts Odorous House Ants?

Like many other pests, odorous house ants are attracted to three main things: food, shelter and water.

Odorous house ants will feed on virtually anything. Outdoors, they prefer honeydew produced by other insects like aphids and mealybugs, but they may also eat plant nectar and even small dead animals or dead insects.

Related: What are Those Tiny White Bugs in or Around Your Home?

These ants prefer sugary foods and may eat many common pantry items, as well as dog food and grease. When searching for food indoors, they may be seen in or near garbage cans in the kitchen or the bathroom.

Are Odorous House Ants Dangerous?

Odorous house ants are not dangerous. When they enter your home, they're more of an inconvenience, as you'll have to manage the infestation and will need to dispose of and replace infested food. However, because their colonies are so large and they are non-aggressive to members of subcolonies, infestations can quickly become an issue if left undetected.

These ants can also be a nuisance for another reason — they live up to their name. When worker ants are crushed, they produce a foul odor that many people describe as smelling like rotten coconut.

Do Odorous House Ants Bite?

Fortunately, odorous house ants are relatively docile and do not pose a threat to humans. They don't have a stinger, and they only bite when they feel they are threatened or provoked, or when a nest is disturbed.

How to Get Rid of Odorous House Ants

There are a few basic steps you can take to help prevent odorous house ants from establishing colonies in or near your home. These include:

  1. Eliminating piles of lumber, bricks or other debris that could serve as nesting sites
  2. Keeping landscape mulch less than two inches thick and at least 12 inches away from foundations
  3. Ensuring sprinkler systems do not spray directly onto your home's foundation
  4. Sealing as many cracks in the home's exterior as possible
  5. Keeping tree and shrub branches trimmed to prevent them from touching your home
  6. Checking for and repairing any leaks under sinks and near tubs or toilets
  7. Keeping foods, including pet food, stored in airtight containers
  8. Ensuring garbage cans are tightly closed
  9. Wiping down all counters and cleaning up crumbs
  10. Keeping gutters clean of leaves and debris

In order to effectively control odorous house ants, the main colony and all subcolonies must be located and treated. Because of this, it's best to contact a pest control company like Terminix® to help assess the situation. Regular inspections and treatments may be required to remove the infestation.

For cases in which colonies can't be located, baits may be effective. Foraging ants will return the bait to the colony, where it should kill off the population. However, it may take several applications before the bait is effective. Pest control professionals can place the baits and determine if the colony has truly been eliminated.