Nuisance Ants

Pest Control – Nuisance Ants

Odorous House Ant

Odorous House AntOdorous house ants are found throughout the United States, Canada, and Mexico. The common name of this insect is derived from the offensive odor that is produced when they are crushed.

Odorous House Ants are very common in western Washington. They are less common east of the Cascades, where conditions are much drier.


House Ant Close UpOdorous house ant workers are all the same size (monomorphic). They are approximately 1/16 inch long and have a brown to black color.





Ant HabitatOdorous house ants have colonized a wide range of habitats and can be found nearly everywhere from sea level to about 10,500 feet. They nest in pastures, turf, forests, and bogs, under rocks and logs and in houses. They also build nests under stumps and the core of dead trees, in abandoned mammal nests, and debris. They build their shapeless nests just below the surface. Odorous house ants tend to move their nests when disturbed.

There are typically thousands of workers and many queens in each colony. Newly produced queens mate with male reproductives within the colony. Some queens also mate with males from neighboring colonies. Reproductive flights occur usually in midsummer. Colonies may develop by “budding”� when a new queen(s) leaves the parent colony with workers or as a single fertilized queen.

Workers move quickly and usually travel in columns. When disturbed they move around erratically with abdomens raised while releasing a distress pheromone, which draws more workers to the site. Food consists of honeydew collected from aphids, mealybugs, leaf hoppers and scale insects. Workers also gather living and dead insects, as well as nectar from plants.


Ant with Egg
Photo by Will Ericson

Odorous house ants have become a major nuisance pest by infesting houses. They eat and contaminate a wide variety of household food.


Control can be difficult because they often have multiple nesting sites, moving regularly to avoid inclement weather conditions. They cooperate and exchange food, workers and larvae between the different colonies. Odorous house ants may develop huge super colonies, or many satellite colonies located close to a main colony. These ants will forage day and night.

The large size of colonies, number of colonies, wide variety of food sources and multiple queens per colony make this a formidable foe to eradicate. This is an ant pest that is best treated by a professional. Call us, and we can help.

Moisture Ants

Moisture Ant Nest“Moisture ant” is a collective name that includes a number of ant species which are similar in appearance and size, and they all tend to infest wood. These are the yellow ants, which are not found in our region, and the cornfield ants. Most pest species are yellow; here they tend to be a dark brown, from 3-5 mm long. The workers are all the same size.

Colonies usually occur in decomposing wood, but also may be found in soil. They feed on sweets and fungus, and become a nuisance around homes. Reproductive swarms usually occur late summer to fall. These ants are frequently seen in houses in areas where moisture has initially damaged the wood. Colonies are established and grow in wood that is already in an advanced stage of decay.

Wood Damaged by AntsThese ants are not considered a structural pest as the damage developed before the colony was established. Removing the decayed wood and replacing it with new material along with correcting the condition that led to the decayed wood in the first place will eliminate infestations of Moisture ants. These ants construct galleries from the rotten wood to produce their nests.

Cultural Control

Correct leaking plumbing, toilet seals, caulking around tubs and windows; and any other areas where water may damage wood or create moisture problems. Do not allow wood to come into contact with soil unless it is pressure treated. Moisture ants are often found in form boards left in place during construction. Remove form boards as well as other wood debris in crawl spaces and near the foundation. Replace any rotten wood within the structure. Remember, long-term control requires eliminating the moisture problem and replacing or removing wet, rotting wood.

Chemical Control

These ants are not structural pests but they are indicators of a moisture problem. They also can become a nuisance when found in homes. To eliminate them usually only requires changing the environment by eliminating moisture. Chemical control is not advised unless they are nesting under the house or within the house and begin to emerge in large numbers either as workers or winged reproductives. If this is the case, then chemical control may become necessary. Call us at Action Pest Control Inc. if you need help with moisture ants.

Thatching Ants

Thatching Ant
Photo by Will Ericson

Thatching ants Build mounds from small twigs, grass shoots, leaves, and pine or fir needles. Thatching ants are beneficial, since they are predators of many other insects. However, they can become a severe annoyance when their mound is built near homes, playgrounds, gardens or any other locations of human habitation. They often damage small trees or plants near their nests. Thatching ants are aggressive and produce a severe bite which they spray with formic acid to create a painful burning sensation. Blisters often form if the skin is not washed.

Most thatching ants are red and black. A few are solid black. They are fairly large ants, averaging from 3/16-5/16 inch long. They have a depression or dip in the thorax when viewed from the side. The workers vary in size within the colony. Swarming (winged males and queens leaving the colony) usually occurs in late summer.

Thatching ants may be mistaken for carpenter ants, but there is no mistaking the mounds they make. The mounds are usually large and range in size from a foot tall to as much as five feet tall! Where there are thatching ants there is a mound nearby.


Thatching Ant NestBe sure these ants are indeed a threat if you find them residing on your property because, as mentioned, they are beneficial. If you determine them to be a pest, contact us at Action Pest Control inc. to treat for them.