Lawn & Garden
AUBURN UNIVERSITY, Ala. – The ants go marching one by one, or two—or three. Argentine ants give a new meaning to a colony of ants. This invasive species can quickly become hard to manage. Before these ants march into your yard, learn how to identify and control Argentine ants.
What are Argentine Ants?
According to Alabama Extension Specialist Fudd Graham, Argentine ants were introduced to the United States in 1891. Native to Northern Argentina and Brazil, the ants were first found in New Orleans and have since spread from California to Southern Florida.
This ant species can survive globally in any Mediterranean-like climate with mild winters and moderate to high humidity – thus making Alabama a place where they can thrive.
Argentine ants look much like any other common ant.
“Their bodies vary in color from light to a dark brown,” Graham said.
The bodies are about an eighth of an inch long and are all the same size. When crushed, they omit a musty odor.
Most notably, Argentine ants are often identifiable by the long trails of worker ants. This is due to their enormous populations.
When long lines of marching Argentine ants are identified, it is most likely a concern for landowners.
With several nests, hundreds of queens, thousands of cooperative workers and no known enemies, these ants grow in volumes.
“This is possible because of an unusually low level of interspecific aggression that enables high population densities,” Graham said. “This allows the Argentines to outnumber and compete effectively with other insects when foraging for food and habitat.”
Argentines have no known natural enemies aside from our native ants and the imported fire ant. They can displace native ants and severely disrupt natural food webs. With such large populations, Argentines can quickly become difficult to manage.
Human vs. Ant
If Argentine ants have already infiltrated your home, a bait is the best method for management. Argentine ants prefer sweet or protein-based baits.
Place the bait along the trail for the ants to find and carry back to the colony. “It may take a day or so for the ants to eat the bait before they disappear,” Graham said.
To further control in homes, sanitize and remove all food scraps, close points of entry to the home and remove excess water sources.
The last line of defense for your house is to find and treat the nests outside.
Nests can be located by following trails back to the colony (treating the trail as you go). Outdoor Argentine ant nests can be drenched with a residual insecticide by using a compressed air sprayer.
Colonies are often in flowerbeds, mulch, leaf litter, under rocks, timber and under tree roots.
If Argentines become too numerous, perimeter treatments will repel foraging ants and prevent them from invading the structure.
“Insecticides used for these treatments should be a wettable powder or micro-encapsulated formulation labeled for this type of application,” Graham said. “If caught early in the year before numbers are too large, use baits outside along trials to keep populations down.”
No matter which method you use, the area should be inspected on a regular basis and retreated as needed.
Argentine ant management is a continuous battle.
For more information on Argentine ants, visit the Alabama Extension website, www.aces.edu.