Updated on September 23, 2022
There’s an old saying that goes “strength in numbers”, an this can certainly be true of pests, as well.
In fact, ants tend to be one of the most prevalent pests out there, from pavement ants and carpenter ants to frequent indoor invaders such as grease ants and the umbrella term of sugar ants (which include ghost ants and pharaoh ants).
But as in any video game, ants have a boss-tier version – and no, it’s not the infamous fire ant. Instead, it’s a seemingly insignificant species known as the Argentine ant.
Getting to Know Argentine Ants
Argentine ants (Linepithema humile) are a curious bunch and while you might not immediately recognize the name, you’ve likely heard of them at some point in recent history.
However, these little pests are quite dangerous for reasons not readily apparent and should be dealt with ASAP.
Identifying Argentine Ants
It can be really hard to distinguish these ants at times because they’re so small. Workers tend to be up to 1/8 inches long and the queens about twice that length.
They’re usually a light to dark brown with a shiny exoskeleton and a single erect node between the thorax and abdomen. Perhaps the easiest way to identify them, though, is the musty smell they release when crushed.
Spotting Argentine Ants
The easiest way to identify an Argentine ant infestation is to catch them in action. These critters work tirelessly, forming long, straight columns of workers heading to and from a food source that won’t abate until that food source is gone.
What Do They Eat?
Argentine ants love sugary foods and are one of many species to actively tend aphids, mealybugs, scale, and other piercing insects as cattle in exchange for their honeydew. They also enjoy fruit juices, syrups, and other plant secretions.
However, they’re also known to go for proteins, including actively killing and eating other ant species and even common household pests such as cockroaches and termites.
Do Argentine Ants Bite?
Despite a number of tales from the early 1800s of Argentine ants crawling into cribs and bassinets to attack babies, the bite of an Argentine ant is completely harmless due to the tiny size of their jaws and you’ll likely never even notice if you’ve been bitten.
So Why Are Argentine Ants So Dangerous?
What makes this species so dangerous has little to do with the ants and everything to do with their colony size. Unlike many other species, Argentine ants have multiple queens that can live for several years, with workers having an exceptionally long one-year life expectancy.
The species has spread to every continent except Antarctica, including many islands. Supercolonies spanning up to thousands of miles have been documented in Australia, California, and Europe, despite their original habitat being fairly small.
Queens mate within the colony’s walls, then lead a number of workers away to create satellites which often connect back to the main colony to create supercolonies with populations sometimes in the billions. This means the territory of a single colony could theoretically spread over time to encompass entire continents if not dealt with.
New colonies tend to be founded in warm, damp environments including mulch, debris, under plants or logs, and in damp soil. They cultivate piercing plant pests, wreaking havoc in agricultural settings.
Workers will create supply lines to indoor locations that have food or sources of moisture, although they rarely build indoor satellites. The risk is greater for this if the colony was flooded or there are drought conditions, at which point they’ll make their home in walls or floors much like other ants.
Argentine ants in different colonies usually cooperate with one another but are extremely aggressive to all other species of ant.
While found throughout the southern States, they’re most notable in California, where they’re causing the extinction or endangered status of many native species, such as the horned lizard.
It’s unknown how many species have already gone extinct worldwide due to this pest, which is ranked among the world’s 100 worst invasive animal species.
Argentine Ants vs Pharaoh Ants
These two ants are nearly identical in appearance, leading them to be frequently confused. However, pharaoh ants (Monomorium pharaonis) are slightly smaller at 1/16 inches long, range in color from light yellow to reddish brown, and have two nodes between the thorax and abdomen.
How to Get Rid of Argentine Ants
Best Argentine Ant Killers
Taurus SC is arguably the best Argentine ant killer around and used by most good pest control companies.
If you have a hard time finding it, Quali-Pro Imidacloprid 2F also works well. Neither are cheap but Argentine ants aren’t as easy to get rid of as typical sugar ants.
NEVER Use Repellent Sprays
When Argentine ants sense a repellent, the nest panics and will scatter, forming satellites around the repellent-treated area. Unfortunately, most of the insecticidal sprays out there double as repellents.
Even using natural products that double as a repellent can leave behind residue that will put a colony in alert status.
The only products that seem safe to use are those with Fipronil or Imidacloprid as the active ingredient. Fipronil products create a barrier around your foundation and won’t startle the colony when used solely as a preventative.
Use Contact Killers Sparingly
Contact killers are great for some pests, but not so great for others. If you choose to use a homemade contact killing spray, such as a neem spray or soapy vinegar water, be sure to use them sparingly.
Any sudden drop in population will set the queens off, which is the last thing you want to do.
ALWAYS Target the Queens
Naturally, the real threat here are the queens, not the workers. Any method you use should ultimately be slow-acting so that it can get to the queens and take them out. And even if it doesn’t, slow-acting poisons will be far less likely to cause alarm.
Just remember, there are a lot of queens (as many as 15 per 1,000 workers) you’ll need to get through.
In the Home
Let’s look at three control methods you can use indoors. Keep in mind, you need to be following the ants to find out their entry points (and sealing them) as well as to find out where the colony is so you can possibly deal with it as well.
Method 1: Diatomaceous Earth
Also known simply as DE, food-grade diatomaceous earth is an all-natural and safe product that works extremely well on a wide range of small critters and especially against bugs.
Simply dust along the trail area and as the ants walk over it, the crushed microscopic fossils will shred their exoskeletons, causing them to slowly dehydrate to death.
Method 2: Boric Acid Bait
Mix one teaspoon of boric acid per cup of bait (peanut butter or jelly are both great options), then place a little of the bait on some wax or parchment paper and place it along the ant trail. The ants will naturally want to harvest it and take the spoils back to the colony.
Boric acid slowly eats away at their digestive systems, killing any ant that consumes it. Even better, if you use peanut butter or bacon grease, the workers will feed it to the queens and larvae, which prefer proteins over sugars. Just be careful to keep these baits away from pets or children, as they’re toxic.
See Also: How to Use Borax to Kill Ants
Method 3: Liquid Baits
This combination is currently used to protect NAPA Valley and is being evaluated by the USDA for large-scale use.
However, good old fashioned Terro ant bait will also work, just not as well.
- Attracts & Kills – Kills common household ants including acrobat, crazy,...
- Kills the Ants You See & the Ones You Don't – As worker ants discover the...
- Works Fast – You should see a significant decrease in the number of ants...
In the Garden
Companion planting (using plants such as Russian sage, basil, peppermint, and marigolds to repel a lot of common garden pests) won’t necessarily repel Argentine ants, but it does keep their “livestock” from infesting your garden. As a result, this is perhaps the only repellent method available that won’t cause a colony alarm.
You can also use the aforementioned KM/Greenway combo near colony entrances for an effective (and deadly) solution.
Read Also: 15 Ways to Get Rid of Ant Hills