Types of Ants :: Odorous House Ants :: Printer-Friendly Version
Ant Origin & Distribution
Odorous house ants have gained the reputation of being one of the most common pests entering structures in the United States. They are native to North America, and occur in a wide variety of habitats from sea level to 11,000 feet. These ants are a common structural pest in Northern California, Oregon, Washington, Tennessee, Mississippi, Arkansas, and lower Midwestern and Mid-Atlantic states.
Ant Identification
Odorous house ant workers are uniformly brown to black ants. The size range for workers is from 1/16" to 1/8" in length. Within a given colony, the workers are all the same size (monomorphic). When workers are crushed they emit a rotten coconut odor.
Ant Biology
Colonies of odorous house ants contain multiple queens and range in size from a few thousand ants to tens of thousands of ants. New colonies can be formed by winged male and female ants (swarmers, alates) after they mate in the nest, or after a nuptial flight. New colonies are also formed by "budding" in which one or more queens, workers and brood leave one nest to start a new one. As outdoor populations grow, multiple nest sites can be interconnected by foraging trails to form super colonies covering large areas.
Odorous house ant outdoor nests can be located in almost any protected area, such as under objects on the ground or behind and within stacked and piled items. Nests are often found under stones, logs, landscape timbers, patio blocks, debris or under loose bark and in the cavities of trees. They are also common in stacks of firewood, lumber, bricks, rocks and other materials especially in shady, moist areas. If conditions become unfavorable, their nests can be quickly moved to a more favorable site. Indoor nests can be found in moist areas and near moisture sources. Nesting occurs in areas such as bath traps, under toilets, in wall voids near hot water pipes or heaters, and in crevices around sinks and cupboards.
Ant Habits
Odorous house ants are strong foragers with hundreds of ants trailing between nests and food sources. They trail and forage both day and night, temperature permitting. Indoors, where temperatures remain relatively warm, activity can occur year round. Outdoors, activity occurs at temperatures as low as 50° Fahrenheit. When conditions and the availability of food become unfavorable outdoors, ants may move to indoor areas seeking more favorable conditions and food.
As is typical for many trailing ants, odorous house ant trails often follow structural guidelines. Outdoor trails can be seen on trees, edges of sidewalks and driveways, at the base of foundations, and on structures. Access to structures can occur from the ground or over tree branches and shrubs. Once on the structure, these ants enter through cracks and crevices in exterior walls and around windows and doors. Inside, trails can be seen along baseboards, carpet edges and near food sources such as pet food bowls.
Odorous house ants are omnivores, feeding on dead insects, small dead animals such as lizards, and on honeydew, a favorite food produced by plant sucking insects (aphids, scales). Indoors they prefer sweet sources but will feed on other foods including pet food left in bowls on floors.
Ant Control
If you think you might have an odorous house ant infestation in your home, it's imperative that you contact a certified and licensed pest control professional to inspect the situation and confirm identification. Experts will advise against do-it-yourself options, as it is much more efficient and cost-effective to have a trained set of eyes identify the correct ant species and recommend effective treatment options specific to an individual infestation. Improper do-it-yourself options may result in killing a few ants, while the rest of the colony simply relocates to other areas around and inside the structure.