Courtesy of University of Nebraska-Lincoln
The Odorous House Ant (Tapinoma sessile) is a native species, found throughout the United States. It earns its name by producing a foul, "rotten coconut" odor when crushed.
They are often confused with the pavement ants, but has only 1 node.
The workers are about 1/16–1/8-inch (2.4–3.25mm) long. The body is brown to black in color. The antennae have 12 segments.
Females in the nest lay one egg daily. It takes an average of 24 days for the young to reach adulthood. Colony size ranges from 100 to 10,000 Ants, and can be easily driven away by invading Argentine Ants.
They forage day and night The nests can occur in a great variety of situations. Inside, these Ants usually construct their nests in wall voids, especially around hot water pipes and heaters, in crevices, sinks, cupboards, etc. Outside they are found in exposed soil, usually shallow, often located beneath a board, brick, stone walk, etc. They are most likely to enter buildings when their honeydew supply or sweet supply of food is reduced by natural occurances such as rainy weather or autumn leaf fall.
They can feed on anything such as insects, honeydew, seeds, and plant secretions, but do prefer sweets. They are extremely fond of honeydew and attend such honeydew-excreting insects as plantlice (aphids), scale insects, and mealybugs.
Odorous ants as well as other ants lay down a chemical trail of pheromones. Ant trails occur between nest sites and food sources. When baiting it is important to look for their trails and place the bait there.
How to Get Rid of Odorous Ants
Unless you use a non-repellent spray such as Taurus SC, baiting is the preferred treatment over typical residual spraying. Baiting is the most reliable way to eliminate the entire colony. When choosing Ant baits, it is best to choose from both the sugar-based baits and protein/grease-based baits. If using a spray, choose a non-repellent type unless you are treating the nest itself.
Why Ant Bait?
The use of residual sprays or dusts stress Ant colonies, causing them to split into sub-colonies and scatter. This scattering, also called budding, multiplies the number of Ant colonies, and thereby multiplies your Ant problem.
When you bait, use a slow-acting bait. Quick-kill insecticides and baits will only kill the foraging Ants, not allowing those worker Ants to take the bait back home to feed the queen, nest workers, and brood.
If the Ant bait that you are currently using is not effective (if the Ants are not visiting the bait) you will need to change the baits. Slow-acting baits provide a variety of the foods the Ants find in nature. Examples are: other insects (proteins/grease-based baits), nectar, aphid honeydew, and plant products (sugar and carbohydrates found in sweet-based baits).
Choosing a bait requires an understanding of the nutritional needs of the colony. To be sure that you have all the baiting needs met, you may want to be ready with a sugar/carbohydrate-based bait, a grease/fat-based bait, and a protein-based bait.
IMPORTANT NOTE: REMOVE ALL OTHER FOOD COMPETITION WHEN BAITING AND LEAVE THE BAIT ALONE ONCE THE ANTS START FEEDING ON IT.
Recommended Ant Baits
Sweet Feeding Cycles:
The powerful, slow-acting non-repellent active ingredient, thiamethoxam in Optigard Ant Gel knocks out workers, brood, and queens.
Baits that feed both Protein /Grease and Sweet cycles:
InVict AB Insect Paste is an all around insect bait containing 0.05% Abamectin (botanical insecticide)
Spraying for Odorous Ants with Non-Repellents
The best insecticides for Ant control are non-repellent insecticides such as Taurus SC, Termidor SC, Optigard Flex, Alpine Aerosol, and Phantom Aerosol. Termidor SC and Taurus SC are labeled for inside usage.
Unless you can treat the nest directly, spraying is not an effective solution for Odorous House Ants, unless you use a non-repellent insecticide or "undetectable" liquid treatments such as Phantom Aerosol or Alpine Aerosols (both labeled for inside use). Optigard Flex is another very good non-repellent, also labeled for inside use and very effective against Odorous Ants.
Unlike older insecticides, non-repellent insecticides can't be smelled, tasted, or even felt by pests. They crawl through the treated area, and ingesting treated materials or merely contacting the residual insecticide results in their eventual death. This type of control is incompatible with treatments such as repellent sprays that prevent workers from delivering the non-repellent insecticide residue to the nest.