Odorous Ant

Odorous House Ant Control: Protect Your Home


Scientific Classification: Tapinoma sessile

Class: Insecta; Order: Hymenoptera; Family: Formicidae


The odorous house ant frequently wanders into manmade structures for the combination of warm, moist spaces and sugary treats. Given their wide-ranging diet, the pests are capable of surviving in a variety of environments and situations. Furthermore, the high adaptability of the insects makes them particularly bothersome and invasive.


What Do They Look Like?

odorous house ant identification
odorous house ant

Size: Odorous house ant workers are monomorphic meaning they are all about the same size. On average, the pests range from 1/16 to 1/8 of an inch in length.

Color: The common ant species appears uniformly brown to black.

Characteristics: All odorous house ants possess a head, antennae, an uneven thorax and an abdomen. Fortunately for the homeowner, these ants do not have stingers and are unable to bite.

Geographic Range

Widely distributed across the North American continent, odorous house ants mostly populate the United States but also have a presence in Mexico and southern Canada. The insects occur in nearly every type of habitat and have been found at elevations ranging from sea level to 11,000 feet. Found in nearly every U.S. state, odorous house ants are particularly prolific.


What Do They Eat?

Sugar serves as the main source of sustenance for the odorous house ant. Honeydew produced by other insects, particularly aphids remains a staple in the diet of the odorous ant species. The pests even offer protection to the insects that produce the sugary substance. Other common food sources include honeydew from (aphids, mealybugs and scales), nectar from flowers, fruits, honey, pastries, syrup and any other sugary food. Protein in their diet is typically obtained from feeding on very small insects and their eggs, such as springtails and Zorapterans. In fact, they will consumer their own eggs as a means of survival when necessary.


Depending on the area odorous house ant colonies range in size from small to extremely large. Smaller colonies range from 15 to 30 workers and include a single queen, while some of the largest reported colonies swell to as many as 500,000 worker ants and feature several queens. As a result, larger colonies tend to maintain several nest sites. Odorous house ants go through a life cycle of complete metamorphosis featuring an 11 to 26 day egg phase, a larval stage that lasts between 13 and 29 days, a 2 to 3 day prepupal phase and a pupal stage that ranges from 8 to 25 days in duration. The pests prefer to mate within the colony as opposed to swarming and establishing new nest sites.


  • Look for adult ants in later winter to early spring.
  • May notice a rotten, coconut-like odor.
  • Look for damaged food storage containers, especially those holding sugary foods.

Problems Caused by Odorous House Ants

Odorous house ants don’t transmit diseases and aren’t capable of biting. Most problems caused by odorous house ants center on their preference for sugary foods and their willingness to forage in kitchens and pantries. The pests generally invade homes in large numbers and are therefore considered a nuisance.

Signs of Infestation

Spotting adult ants in food supplies usually points to the existence of a home infestation. Finding a nest also clearly reveals an odorous house ant problem. Indoor nests may appear in wall voids close to pipes or heaters, bath traps, wood damaged by termites and beneath toilets, while outdoor nests crop up under leaf litter, boards, landscaping timbers, piles of lumber or firewood, bricks, rocks, cardboard and similar debris. When crushed, odorous house ants emit an aroma similar to the smell of rotten coconuts. The unpleasant scent is usually noticed when a nest is discovered or the ants are crushed.

Prevention Tips

The key to prevention centers on fostering an unfavorable environment for odorous house ants. Caulking or sealing any cracks in the foundation or around doors and windows is a good first step. Adhering to proper sanitation practices also discourages odorous house ants from invading. Seal foods in airtight and ant-proof containers. Keep trees and shrubs well-maintained, and avoid letting the vegetation come into contact with the outside of the home. Finally, clear any debris that would make a suitable nesting site for the pests.

Tips for Removal from Home

Since odorous house ants leave chemical trails while scavenging, sponging the foraging adults with soapy water reduces the likelihood of more ants returning. Baits also work especially well as long as they target sugar-loving ants. Odorous house ant infestations that involve an indoor nest or multiple nesting sites often require the help of a pest control professional. The use of insecticides may prove necessary for control and professionals possess the experience, training and proper certifications to manage these pests.

Ants use odors for communication. Scientists think this may be because ants spend a lot of time underground in their tunnels. When they are above ground, ants also use sounds and visual signals for communication.

Ants produce the chemical odors with special glands in their bodies. Scientists call these chemicals pheromones. An ant worker can produce several different pheromones. Since there can be thousands of ants in a colony, there would probably be a lot of pheromone (and odor) floating around in the atmosphere inside the nest. Many species of ants give off a distinctive odor. Some of these odors are very unpleasant.

Tapinoma sessile (Say) is a species of ant that is native to North America. When the workers are disturbed, they run around with their abdomens raised in the air. They give off an odor that reminds many people of rotten cocoanut. These ants are found in most areas of the United States. So many people have smelled the odor that these ants received the common name of Odorous House Ants.

Since the odorous house ant is so widespread, many people have seen the workers marching in a line. These small, dark ants enter homes through windows, vents, and cracks in the foundation. They make nests inside of walls and under the bases of cabinets.

The first step in controlling odorous house ants is a careful inspection. Begin outdoors and look for trails of ants, nesting sites, and any entryways they could be using. Store firewood on a rack and move it away from the house. Rake mulch and dead leaves away from the foundation. Trim any shrubs and tree limbs that are touching the house.

Caulk any openings around doors and windows. Make sure exterior doors close tightly and replace any missing weather-stripping. Repair any damaged screens on windows and vents โ€“ check the attic vents too.

Control of odorous house ants usually involves applying ant bait. If the trails lead outdoors, the bait can often be put outdoors. This will draw the ants out of the house. If the ants have made a nest indoors, it is sometimes necessary to drill tiny holes and apply insecticide dust inside the walls. Many homeowners find it easier to let pest control professionals take care of these pests.

Ants get their food by sending out scouts to find it. Scientists call the ants that search for food foragers. When the foragers find food, they take a sample back to the nest. They mark the trail so they can find their way back to the food. When they get to the nest, the foragers recruit more ants to help carry the rest of the food back to the nest.

When the foragers have brought the food to the nest, they share it with the rest of the ants in the colony. Adult ants can only swallow liquid food. If the foragers find solid food, they feed it to the larvae. The larvae convert the solid food to liquid then the foragers take it back. The foragers can share the liquefied food with the rest of the colony. Most adult ants share food from mouth-to-mouth.

When scientists learned how ants get food, they realized that it could be used to control ants. Scientists thought it would be possible to give the ants a food substance that had an insecticide mixed in it. After some testing, they found that they could make these products in the form of solid pellets, gels, and liquids.

Odorous house ants will readily take liquid bait. The liquid contains a sweetener so it is attractive to the ants. The foragers do not die on the trail back to the nest. However, there is enough active ingredient to kill all of the ants that get a share of the bait. Liquid bait should be placed in a shady area so that it doesn’t evaporate. Bait stations should be kept filled with fresh bait as long as the ants are feeding. Pets and wild animals should not have access to the bait station.

Bait that is made in a gel is very effective for controlling odorous house ants. They take the gel back to the nest and share it with the colony. There is usually an applicator for applying the gel into cracks and crevices. Some of the gel formulations are sensitive to heat. If the gel gets too hot, it can become runny. This can discolor or damage surfaces, so users should be careful.

Odorous house ants will also take solid bait pellets. The foragers recruit other workers to help carry the pellets back to the nest. The larvae must liquefy the solid pellets, so this type of bait can be slower acting than liquid or gel formulations.

Bait should be placed near the odorous house ant trails. This ensures that the ants will find the bait. It also makes sure that other types of ants do not steal the bait from the odorous house ants. If the ants are trailing into the house for food, the bait should be placed outside. This will attract the ants to come out of the house.

When the ants begin to take the bait, there will be hundreds of workers at the bait station. It often looks like the ant problem has gotten worse. There is a risk of running out of bait before all of the ants have gotten to eat some. The bait station should be kept full until the ants have stopped feeding.

Treating ants with bait requires patience. It is often necessary to change baits when the ants’ food preference changes. Many homeowners find it simpler to have a pest control professional take care of these pests.