Argentine Ants Linepithema humile
Workers of this species are about 1/8-inch in
Varies from dark brown to black, and the body
is often shiny in appearance.
The colonies of Argentine ants can grow quite
large and contain tens of thousands of workers and numerous queens. Each colony will be divided into sub colonies
located in various suitable harborages connected by established trunk trails. These sub colonies will number from a
few hundred to thousands of individuals. Since members of two separate colonies are not aggressive toward each
other, colonies will often combine with one another. This creates huge super-colonies that may extend over several
properties. Argentine ants are very aggressive and will drive out native species of ants, creating an environment
where they are literally the "king" of the anthill, so to speak. Their primary food source during the warm months
is the sweet honeydew produced by aphids and mealy bugs. The presence of fruit trees, roses and other plants that
attract aphids often contributes to Argentine ant infestations.
Argentine ants reside outdoors, usually in
shallow nests in the soil beneath a stone, board or any other item that provides protection. Small, medium or large
sub colonies will locate themselves in piles of lumber, bricks or debris; in landscape mulch; behind brick and
stone veneer; within and under insulation; and in wall voids or any other suitable void. Argentine ants are the
most common invaders of homes in Southern California. This ant is also very common in homes throughout most of the
Gulf Coast states.
The Argentine ant can be nearly impossible to
control, especially during midsummer in areas such as Southern California. At best, regular treatments keep as few
ants as possible from entering the home or business. General tips for limiting ant infestations
- Eliminating piles of lumber, bricks or
other debris that could serve as a nesting site for ants.
- Keeping landscape mulch less than 2 inches
thick and at least 12 inches away from foundations.
- Ensuring the sprinkler system does not
spray directly onto the foundation.
- Sealing as many cracks in the building's
exterior as possible.
- Keeping tree and shrub branches trimmed to
prevent touching the home.
- Considering re-landscaping to avoid using
plants that are prone to aphids and similar insects. At the very least, treat such plants for aphids regularly.
A tree/shrub company, such as TruGreen, can be helpful with this task.
Argentine ants are very fond of sugar,
especially from the sweet honeydew secreted from insects such as aphids. The ants often “farm” them, protecting
them on the plant they eat, killing any predators, in order to secure a constant honeydew supply!
It helps to keep sheets of plywood, stones and other debris from piling up to lessen the chance of nesting. Using
caulk or any other sealant to fix cracks or holes in the buildings exterior helps keep ants from entering, as well
as keeping lawns and trees maintained and away from structures. Repair any leaky water sources to lessen excess
moisture and move any sprinklers that come in contact with your home.
Omnivorous, they can eat almost anything but prefer sweet foods.
Eggs are white and laid in summer. Larvae emerge after about 28 days. Adult stage reached in about 74 days.
Argentine ants may live in soil, under wood, logs, debris or mulch. They may also nest in branches and cavities
of shrubs and trees. Their nests are often shallow, measuring up to two-inches in depth in open habitats.
Argentine ants are brown in color, measuring about 1/16- inch in length. They have a single node in their
midsection. The eggs of the Argentine ant are pearly white in color and take one week to a few months to
hatch. Like other ant species, Argentine ants pass through the development process called complete metamorphosis.
The larval stage may take up to two months to reach completion. From egg to adult, the life cycle of Argentine
ants ranges from two to five months.
Unlike some other species, Argentine ants have no soldier caste. All Argentine ants are the same
size. They travel with well-defined trails between their web of nests and their food sources. Argentine ants
feed on fresh fruits, buds of plants, sweets, honeydew and oily household foods.
While other ant species have seasonal nuptial swarming flights, Argentine ants do not establish new nests
through swarming. In summer and spring, a queen Argentine ant will leave her nest on foot to establish
new colonies. New nests are constructed around the original, and remain connected to the queen’s old colony,
so workers are sometimes shared between colonies.
Argentine ants kill other insects and invade human dwellings. Over time, the network of interconnecting
colonies could become an infestation. Each colony of Argentine ants can contain millions of insects and multiple
queens. These colonies can populate entire city blocks, and researchers have estimated that Argentine ant
infestations grow at a rate of more than 200 meters annually.