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Posted 06/20/2020 in Ants by Pest Control Approved

Odorous Ants - What Are They and How To Eliminate

Odorous Ants - What Are They and How To Eliminate

Odorous Ants

Tapinoma sessile, or odorous ants, are a common pest across North America. They are known by many names such as the odorous ant, the house ant, the stink ant, and the coconut ant. They are one of the few species that has multiple nests per colony. In indoor colonies, they often have multiple reproducing queens. Like most ants, they work together and have strict roles: worker, drone, or queen. Odorous ants get their name from the unique odor produced when they are crushed.


Odorous ants are dark brown or dull black with a smooth body. The queens and drones have grey wings with yellow veins running through them. These wings are lost after mating. Queens are large, between 3.75 and 4.3 millimeters. Worker ants have no wings and are 3 to 4 millimeters (1/8 to 3/16th inch). Like other ants, their body is divided into three sections: head, thorax, and abdomen.

Their head is square with large eyes. It contains bent antennae used for touch, smell, and communication. Odorous ant’s antennae are shorter than average, with only twelve segments. Their thorax contains six light brown legs. When viewed from the side, their thorax appears uneven, or curved upward. Their most distinctive feature is a hidden node or petiole. This small segment, which attaches the thorax to the abdomen, is visible in most other ant species. In odorous ants, this node is hidden under the abdomen, causing a distinctive upward curve. They are relatively hairless, with only a few small, yellow hairs. When freshly crushed, they smell stale, greasy, or musty. When a dead ant is crushed, or the body sits for a time, it smells like rotten coconut. 


Life Cycle

 In the summer, queen ants rise to mate with male drones. In warmer climates, mating occurs in the early summer; in Alberta, it occurs in late summer. Pregnant queens will either return to their existing nest or form a new nest. Unlike most ant species, odorous ant colonies may have multiple fertile queens in the same nest. They can thus reproduce quicker than other ant species.

A queen ant produces eggs seven to fourteen days after mating.  She can lay as many as thirty eggs or as few as a single egg per pregnancy. The eggs are cared for by worker ants for 11 to 26 days. The queen does not provide any care. However, a newly pregnant queen may care for her own eggs in specific circumstances, mainly if she has just created a new nest. But, often, worker ants will follow her to a new nest. After hatching, the ant larva develops for 13 to 29 days before they molt and become pupa. In summer, this process is much shorter. Ant pupae have no cocoons and are white with no markings. As they mature, they turn brown and yellow. They become fully formed ants after 10 days to three weeks as pupae. 



Outdoors, ant nests are found in soil, logs, or vegetative debris. They are often found under rocks or logs. Odorous ants are surprisingly easy-going and will nest with other ant species. They often have multiple nest areas and will use these areas year after year.

Odorous ants often come indoors during a heavy rain. Their nests are often made in walls or underneath flooring.  They are drawn to areas with moisture like bathrooms. Their habit of building multiple nesting areas and their frequent movement between them makes these ants difficult to eradicate. 



Like many ants, odorous ants are drawn to sweet substances. Their main food source in the wild is the honeydew produced by aphids and scale insects. In some cases, the ants develop a mutually beneficial relationship with scale insects. The ants protect the scale insects while the insects provide the ants with fresh honeydew. In urban environments, they enjoy human food like ice cream, butter, cheese, and fish. They can sometimes be seen eating carrion. Odorous ants will often enter the home searching for water or sweets. 


Are They Dangerous? 

Odorous ants are not dangerous. They do not have a stinger but can bite if threatened. Their bite is mildly painful and may case mild itching or redness. Ant bites rarely require any treatment. They cannot transmit disease through their bite. However, they can pass on bacteria if they walk on a food surface like a counter top or table. They most frequently carry salmonella or e. coli. They pick up this bacteria by traversing through bathrooms and garbage. Occasionally, they can carry dangerous staphylococcus or streptococcus bacteria. A staphylococcus infection can look like a pimple or boil. Fortunately, it is easily be treated with antibiotics. In general, odorous ants are a nuisance but not a health threat.

Ant Prevention Tips: 

  • Repair rips in screens or mesh
  • Fill cracks or gaps in windows and doors
  • Keep house free of crumbs
  • Brush pets when they come inside
  • Store food in sealed containers

Removal Options: 

  • Spray ant scent trails with vinegar
  • Use ant bait traps indoors
  • Remove outdoor colonies near windows and doors
  • Use aerosolized insecticide near entry points.