Argentine Ants Not Crazy Rasberry Ants

Argentine ants seem to be causing alarm to some homeowners. Many people are confusing them with the Rasberry crazy ant (recently in the news); since they form dense foraging trails and often invade homes and other structures. Argentine worker ants are all the same size, about 1/8-inches in length and are dull brown in color. These ants have multiple queen colonies allowing workers to move freely between colonies. Populations sometimes appear to be a giant super colony. Even though, argentine ants do not bite or sting, their colony size can be in the hundreds of thousands.
These ants usually nest in cavities in soil, under rocks, in flower beds and in branches or cavities of trees. They eat sweets, fresh fruit, and buds of some plants and tend honeydew-producing insects, such as scales and aphids. These ants travel in distinctive trails along sidewalks, up the sides of buildings, along branches of trees and shrubs, along baseboards, and under edges of carpets.

Some Control Options:
Some Non-Chemical Control Options:

Trim tree branches and other plants so they do not touch structures, since argentine ants can use these branches to get into structures.
Caulk and seal any cracks or little openings around the structure.
Do not stack firewood and building materials next to structures, since these ants can build nests in these materials.
Reduce moisture sources such as leaky plumbing and free-standing water in and around structures.
Clean window sills to remove dead insects, since these ants will feed on dead insects.
Check potted plants for ants before bringing the plants indoors by watering to check for ants moving within the soil.

Some Chemical Control Options:
Spot treatments at points of entry into structures such as around window sills and door thresholds may be effective. Insecticides used for these treatments should be a wettable powder or microencapsulated formulation labeled for this type of application. If colonies cannot be located, bait insecticides can be used. Argentine ants are mostly attracted to sweet baits. Such baits containing boric acid, hydramethylnon and sulfluramid are suggested for control.

Photo of argentine ant worker. Photo by Elizabeth “Wizzie” Brown, Program Specialist-IPM, Texas AgriLife Extension.