St. George & Southern Utah Pest Control Experts

411 the Argentine Ant

By Eric Palmer April 11, 2022
While St George may have the best weather in Utah, there is a downside to its near subtropical climate. The problem is the arrival of one of the planet’s top 100 invasive species – the Argentine ant (Linepithema humile).


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While St George may have the best weather in Utah, there is a downside to its near subtropical climate. The problem is the arrival of one of the planet’s top 100 invasive species – the Argentine ant (Linepithema humile).

This seemingly insignificant insect has spread across the globe and is now found on all continents, except Antarctica and some Oceanic islands. It is an aggressive species with the ability to create vast colonies. And it has wrought havoc wherever it has established a presence.

What is an Argentine ant?

Argentine ants are, at first glance, much like any other ant. The adults are brown and about 1/16” (2 to 3mm) long. And like other ants, Argentine ants are social insects, living and working in colonies controlled by queens.

But looks can be deceiving. This ant has become one of the most invasive species on the planet because it is unlike other ants in one very important aspect.

That difference is that Argentine ants can have multiple queens in a single colony. As they are not normally territorial among their own species, the ants move freely from one nest to another. This allows Argentine ants to exist in huge ‘super colonies’ of nests, that may include millions of individual ants. These ‘super colonies’ can extend for hundreds of yards. Amazingly, in some places, they even cover hundreds of miles.

Argentine ants are always aggressive toward other ant species. Combine that with the huge numbers in a single colony and these ants can be a force to be reckoned with.

More than a nuisance

Argentine ants can’t sting and rarely bite unless provoked. They seldom pose a direct threat to humans, aside from their nuisance value when they invade a home, garden, or picnic site. Whereas other ants may throng in their hundreds, Argentine ants can swarm in their thousands. Understandably, many feel that thousands of ants are more than just a nuisance!

These ants don’t have a reputation for carrying diseases as do cockroaches. But as they forage for food, inevitably the ants might wander across unhygienic surfaces. If they invade a kitchen this may result in spoiled food. Or worse. Because of their wandering, they may also transfer such bacteria as Streptococcus.

The main threat from Argentine ants is the damage they do to the environment, which has an inevitable impact on us, often economic.

Environmental devastation

Due to their large numbers and the way they forage, Argentine ants normally find a food source faster than other ant species. This ability to outcompete has led to the local disappearance of several species of ant across the US, along with other larger animals that rely on the indigenous ants.

The Argentine ants’ liking for sweet food means they will ‘farm’ and milk mealybug, aphids, and scale insects for the honeydew they produce. The ants will vigorously protect such plant pests against their natural enemies, allowing the pests to multiply quickly. The host plants soon become weaker, suffering disease and reduced output. Because the ants attack any predators of the plant pests, those begin to disappear, as do the many birds and animals further up the food chain that feed on them.

The impact on the local ecology and biodiversity in southern Utah has the potential to be devastating. As beneficial insect populations are destroyed, the damage may be seen in your garden or the wider agricultural industry.

In addition, where large Argentine ant colonies exist, they have been known to attack and kill newly hatched chicks and small lizards, and even destroy beehives.

Lifecycle of the Argentine ant

Argentine ants go through what is called a complete metamorphosis to become adults. An ant will start as a small white egg from which hatches a larva after about four weeks. The white larva pupates after roughly four weeks of growth. After about another two weeks, the adult ant hatches. However, the time taken to develop from egg to adult is very dependent on the temperature.

The lifespan of the ant depends on its role in the colony. Workers may live for a year. Males might only live a few days or weeks after hatching as adults, whereas queens can live from 10 months to several years.

With potentially up to 300 queens for every 1,000 workers in a colony, and with each queen laying as many as 60 eggs a day, it is not hard to see how the colonies grow so quickly.

Bizarre rituals

The reproductive cycle of Argentine ants is more complex than other ants. Most ant species expand their territory by sending out winged males and females to start a new nest. Argentine ants, on the other hand, can spread either by winged adults leaving the nest after mating or by the more common method of a mated unwinged queen simply leaving the nest accompanied by a small group of workers to start a colony, a process called budding.

The ability of nests of Argentine ants in the same area to co-exist amicably enables queens and workers to move between the different nests without being attacked and to safely start new ones nearby, extending the range of the colony.

With the onset of cold weather, most colonies will become dormant, and mated queens will stay in the nest and wait until spring to lay their eggs. A bizarre, and as yet unexplained, ritual happens every spring when as many as 90% of the queens in a colony are killed by the workers.

Nests - a moving target

Argentine ants usually build their shallow nests in damp locations. The nests might be under boards, large rocks, or even in large potted plants. In a garden setting, the need for access to water may mean nests are located near a dripping tap or gutter downpipe.

The colony also needs access to food. The ants prefer sweet items but at certain times of the year may favor more protein. Your kitchen may be regularly invaded by hordes of Argentine ants looking for food but the source of the problem will normally be found outside the house.

An Argentine ant colony is not built in a fixed location nor is it a network of tunnels and chambers. It is a frequently shifting complex of temporary nests. This constant relocation is one reason why these ants are hard to eradicate.

In cold or wet weather, the ants may move inside your home. Cracks in walls or branches leaning against an outside wall are some ways these marauding pests can shift their nests into your house.

Win the battle!

Battling an army of thousands or tens of thousands of ants may sound like a daunting task. Due to their frequent nest shifting and multi-queen colonies, Argentine ants are not easy to eradicate and require a different approach from other ants.

Sealing cracks in walls, removing water sources, keeping food in sealed containers, and cutting back foliage that brushes against the walls of the house are ways to minimize home invasions by Argentine ants.

If you have a problem with ants, don’t wait. Call your residential pest assassins at Southwest Exterminators. We have the experience to deal with ants – in small numbers or large. Stop the problem now before it gets out of hand!


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