Most Wanted Ants: Argentine ant


October 27, 2020


An Argentine worker ant. PHOTO COURTESY OF NPMA

Linepithema humile

Alias: Argentine ant


  • This species originated in Northern Argentina near the Paraná River, and adapts well to urban and suburban environments.
  • Argentine ants will persist where other species do not thrive.
  • They may be the only ant species present in many locations.
  • Workers are very aggressive, and often eliminate other ants in the area.
  • Because different Argentine ant colonies may coexist in the same area, the number of colonies in an area may be large. As a result, locating every nest may be challenging.
  • Workers are 1/12- to 1/8-inch long, and are light to dark brown. They have one segmented petiole and 12-segmented antennae with no club.
  • Queens are 1/16- to 1/4-inch long.

Life Cycle

  • Many fertile queens are present in each nest, where they lay eggs.
  • Because mating usually takes place inside the nest, winged forms typically are not found.
  • Queens clean and feed themselves, and are active in feeding and grooming immatures.
  • New colonies may be formed through “budding,” whereby some fertile queens and some workers become isolated from other members of the colony and establish a new colony.


  • Nests usually are located near water and food sources, in moist soil next to or under buildings, along sidewalks and brick or stone walkways, or under boards and potted plants.
  • Backyard landscape features provide an ideal habitat.
  • Argentine ants use cracks and crevices to gain entry to homes in search of food or water.
  • Nests may be located within a structure or other locations not typically considered soil-related, such as under a bathtub set above a slab-on-grade foundation; under the cracks or expansion joints of slabs; or under the insulation in an exterior wall void.


  • Argentine ants prefer sweet foods, especially sugars, syrup, fruit juices, plant secretions, and honeydew.
  • Workers forage for food along paths extending out from the nest, branching out to explore every part of an area.
  • Foragers may enter homes in large numbers, particularly when conditions outdoors become too wet or dry.
  • Foraging range is such that nests may be located in properties adjacent to a customer’s yard and home, making control challenging.


➔ The ants may be found in most regions with Mediterranean climates or with mild winters and moderate to high humidity.

➔ In the United States, they are common in coastal regions, such as California.


➔ Maintain proper sanitation in homes and yards; seal entry points into structures; and remove landscape features (such as those that generate excess water) that provide ideal habitats.


Truman’s Scientific Guide to Pest Management Operations

University of California Riverside, Center for Invasive Species Research

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