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Gregory B. Vaillancourt

B.S. Entomology * OPR 8930
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Argentine Ants

Parts of this information was taken from the "Wikipedia Free Encyclopedia" website: http://en.wikipedia.org/wiki/Argentine_ant

AntsThe Argentine Ant usually nests in the soil, commonly under concrete slabs, but may also be found in any other convenient void, such as in trees, wall voids, under insulation, or under debris on the soil. Soil nests are generally very shallow. Protein foods are part of their diet, but their preferred foods are sugars, including household food products, and fruits in gardens.

Like workers in many other ant species, Argentine ant workers are unable to lay reproductive eggs but can direct the development of eggs into reproductive females; the production of males appears to be controlled by the amount of food available to the larvae. The queens seldom or never disperse in winged form. Instead, colonies reproduce by budding off into new units. As few as ten workers and a single queen can establish a new colony.


The ants are ranked among the world's 100 worst animal invaders. In its introduced range, the Argentine ant often displaces most or all native ants. This can, in turn, imperil other species in the ecosystem, such as native plants that depend on native ants for seed dispersal, or lizards that depend on native ants for food. For example, the recent severe decline in coastal horned lizards in southern California is closely tied to Argentine ants displacing native ant species on which the lizards feed.

Argentine ants sometimes tend colonies, and their protection of this plant pest can cause problems in agricultural areas by protecting plant pests from predators and parasitoids. In return for this protection the ants receive a food as an excretion, known as honeydew. Thus, when Argentine ants invade an agricultural area, the population densities of these plant parasites increase and so too does the damage they cause to crops.

Pest control

Argentine ants accessing a commercial bait station commonly available in the United States. Within two days of this photograph, the ant colony appeared to have been destroyed and had ceased to access the five bait stations which had been placed.

Argentine ants are a common household pest, often entering structures in search of food or water (particularly during dry or hot weather), or to escape flooded nests during periods of heavy rainfall. Argentine ant colonies almost invariably have many reproductive queens, as many as eight for every 1,000 workers, so eliminating a single queen does not stop the colony's ability to breed. When they invade a kitchen, it is not uncommon to see two or three queens foraging along with the workers.

Due to their nesting behavior and presence of numerous queens in each colony, it is generally impractical to spray Argentine ants with pesticides or to use boiling water as with mound building ants. Spraying with pesticides has occasionally stimulated increased egg-laying by the queens, compounding the problem. Pest control usually requires exploiting their omnivorous dietary habits, through use of slow-acting poison bait, which will be carried back to the nest by the workers, eventually killing all the individuals, including the queens. It may take four to five days to eradicate a colony in this manner.

Researchers from the University of California, Irvine, have developed a way to use the scent of Argentine ants against them. The exoskeletons of the ants are covered with a hydrocarbon-laced secretion. They made a compound that is different, but similar, to the one that coats the ants. If the chemical is applied to an ant, the other members of the colony will kill it. The chemical method may be effective in combination with other methods.