10 Facts About Argentine Ants

A pile of genetically-related Argentine ants
A pile of genetically-related Argentine ants
Marc Matteo, Flickr // CC BY-NC 2.0

A supercolony of invasive Argentine ants (Linepithema humile) stretches for 560 miles beneath California, from San Diego to San Francisco. The billions of Argentine ants are unlike other ants in many ways—and they are virtually indestructible. Along with their supercolonies in Europe, Japan, and Australia, L. humile’s global domination is rivaled only by that of human beings. Here’s what you should know about these prolific pests.

1. Argentine ant colonies are ruled by hundreds of queens.

Most ant colonies revolve around a single queen. Growing much larger than the worker drones, she is programmed to mate as quickly as possible, then to leave her nest of origin and establish a new one. In some species, a single queen can lay millions of eggs in a lifetime, producing an army of worker drones and future queens who will go off to build their own nests. But unlike most ants, Argentines are polygynous: Each nest contains multiple queens. In some, they can form up to 30 percent of the population.

2. Argentine ants move their nests frequently.

Nest types vary from ant species to ant species, but those who live in soil commonly dig tunnels and chambers deep into the earth that will protect the colony throughout the life of the queen. L. humile, though, is transient and ever shifting. Argentine ants frequently pack up their eggs and move the entire colony, queen and all, to a new nest, even when there is no apparent threat. Biologist Deborah Gordon told Ars Technica that the ants typically have 20 to 30 shallow nests at any one time, which can be built up in a matter of just weeks.

3. Argentine ants traveled the U.S. before settling down in California.

Argentine ants arrived in the United States from Northern Argentina in the late 19th century, when the first recorded Argentine ant was found in Louisiana in 1891. Researchers believe that the ants hitched a ride to North America in Argentinian shipments of coffee or sugar off-loaded at the Port of New Orleans. From there, they traveled—most likely by train—across the South and into California. Enticed by the Mediterranean climate, one similar to that of its original home in South America, the ants set up shop. By 1907, they’d displaced local native ants and begun their first steps towards total soil domination along 560 miles of California coastline.

4. California’s Argentine ants are more laid-back than their South American cousins.

In side-by-side comparisons of Argentine ants from their South American homeland and California, researchers have found that those from the West Coast are far more mellow than those from Argentina. In studies, it was typical for two ants from different nests to fight when placed in the same vial in Argentina, but in California, ants from different nests rarely fought, even when they were collected from locations several hundred miles apart.

A DNA study of ants from both locations in 2000 revealed a stark difference. In the ants from Argentina, microsatellites—short, uniquely patterned DNA sequences passed down from generation to generation—had more than twice as much variation as the microsatellites of the Californian ants. When two individuals from different nests in California were placed together, they recognized one another as family. The ants from Argentina didn’t, making them more likely to display territorial aggression.

The difference is rooted in the genetic bottleneck the ants encountered on their arrival to the Golden State over a century ago. According to biologist Neil D. Tsutsui, who conducted the DNA study, the ants in California today are all descendants of that founding colony. “It would be as if all of the people in the United States were descended from the Pilgrims who came here in 1620,” he told the Stanford Report in 2004. Instead of competing with one another, generation after generation has worked together to take out native ants and build an immense California colony.

5. Argentine ants protect other insects in exchange for sweet, sweet honeydew.

Two Argentine ants share a tiny blob of honeydew.Davefoc, Wikimedia Commons // CC BY-SA 4.0

Argentine ants love to feed on sweet nectar, but flowers and suburban kitchens aren’t the only source of such desirable foodstuffs. Insects that feed on plant sap, like mealybugs, scales, and aphids, naturally excrete sugar-rich liquid “honeydew” from their butts. To secure a steady flow of the sticky-sweet substance, Argentine ants will fight off the predators of their insect chefs, including soldier beetles and midges. They’ll even relocate their honeydew producers to better food sources or microclimates to get the most they can out of their anal secretions.

6. The California Argetine ant supercolony is one-sixth the size of Southern Europe’s.

The California supercolony, which scientists have named the “Californian large,” is only the second-biggest conglomeration of Argentine ants in the world. The biggest colony is found along Southern Europe’s Mediterranean coast, where it stretches 3700 miles from northern Italy to the Atlantic coast of Spain. The ants, introduced around 80 years ago, now number in the billions. Smaller supercolonies also exist in Japan and Australia.

7. Argentine ants are second only to humans in their scale of world domination.

In 2009, researchers discovered that Argentine ants from three of the world’s largest supercolonies (Southern Europe, California, and Japan) are so closely related that they actually form a single mega-colony. The study, led by Eriki Sunamura from the University of Tokyo, found that when placed together, ants from the three supercolonies refused to fight. Instead, they rubbed antennae in greeting the way L. humile does when interacting with genetically-related individuals.

The researchers believe that the Argentine ant mega-colony isn’t just the largest insect colony ever identified; it rivals that of human colonization around the globe. Presenting their findings in the journal Insect Sociaux, they wrote, “the enormous extent of this population is paralleled only by human society.”

8. A mass execution of Argentine ant queens takes place every spring.

Each spring, just before mating season begins, worker ants go on a killing rampage and assassinate 90 percent of their queens. Entomologists aren’t sure exactly why the large-scale execution occurs, but one hypothesis, published in the Journal of Evolutionary Biology in 2001, suggests that it is a “spiteful behavior” to kill the queens that are less related, on average, to the workers.

In their study, researchers from the University of Lausanne hypothesized that Argentine ants are regularly separated from direct family members through free exchange among the nests. Before mating season begins each year, those that are genetically related band together to kill more distantly related queens. Doing so decreases the nest’s genetic diversity and allows it to be rebuilt with a queen who is directly related to the greatest majority of workers.

The study’s results were inconclusive and the question remained unanswered, yet researchers learned something unexpected in the process. Instead of finding genetic diversity among worker ants, those belonging to each nest were actually a homogenous population. Only the queens were genetic outliers with relatively few familial relationships in each nest.

9. Climate change is making Argentine ants more of a nuisance to humans.

Argentine ants thrive in a Mediterranean climate where winters are cool and wet and summers are warm and dry. When conditions are ideal, they largely keep to themselves, but when conditions are drought-like or extremely wet, the ants move indoors in search of more hospitable climes. Experts at survival, Argentine ants can find food or water that’s been left unguarded in just minutes.

With the climate crisis, conditions in California are becoming more extreme. Hot days, no longer relegated just to the summer months, are becoming more numerous and prolonged. Droughts are becoming more frequent. While these changes are unlikely to harm much of the California supercolony, they are likely to drive the residents of urban nests more frequently into people's homes, making the ants a major nuisance for residents from San Diego to San Francisco.

10. Argentine ants are almost impossible to eradicate.

Individual Argentine ants are easy enough to kill, but an Argentine ant colony is a different story. The California colony has no natural predators and, thanks to their high levels of cooperation and massive numbers, L. humile has effectively destroyed possible competitors and disrupted the ecological balance of native species in the process. Insecticides, which are unable to penetrate into the underground nests, aren’t particularly effective. And because the ants can pick up and move their entire nest so quickly, neither are household control measures such as ant bait. After just over a century in California, Argentine ants are now virtually invincible.

14 Retro Gifts for Millennials

Ravi Palwe, Unsplash
Ravi Palwe, Unsplash

Millennials were born between 1981 and 1996, which means the pop culture they grew up with is officially retro. No matter what generation you belong to, consider these gifts when shopping for the Millennials in your life this holiday season.

1. Reptar Funko Pop!; $29

Amazon

This vinyl Reptar figurine from Funko is as cool as anything you’d find in the rugrats’ toy box. The monster dinosaur has been redesigned in classic Pop! style, making it a perfect desk or shelf accessory for the grown-up Nickelodeon fan. It also glows in the dark, which should appeal to anyone’s inner child.

Buy it: Amazon

2. Dragon Ball Z Slippers; $20

Hot Topic

You don’t need to change out of your pajamas to feel like a Super Saiyan. These slippers are emblazoned with the same kanji Goku wears on his gi in Dragon Ball Z: one for training under King Kai and one for training with Master Roshi. And with a soft sherpa lining, the footwear feels as good as it looks.

Buy it: Hot Topic

3. The Pokémon Cookbook; $15

Hop Topic

What do you eat after a long day of training and catching Pokémon? Any dish in The Pokémon Cookbook is a great option. This book features more than 35 recipes inspired by creatures from the Pokémon franchise, including Poké Ball sushi rolls and mashed Meowth potatoes.

Buy it: Hot Topic

4. Lisa Frank Activity Book; $5

Urban Outfitters

Millennials will never be too old for Lisa Frank, especially when the artist’s playful designs come in a relaxing activity book. Watercolor brings the rainbow characters in this collection to life. Just gather some painting supplies and put on a podcast for a relaxing, nostalgia-fueled afternoon.

Buy it: Urban Outfitters

5. Shoebox Tape Recorder with USB; $28

Amazon

The days of recording mix tapes don’t have to be over. This device looks and functions just like tape recorders from the pre-smartphone era. And with a USB port as well as a line-in jack and built-in mic, users can easily import their digital music collection onto retro cassette tapes.

Buy it: Amazon

6. Days of the Week Scrunchie Set; $12

Urban Outfitters

Millennials can be upset that a trend from their youth is old enough to be cool again, or they can embrace it. This scrunchie set is for anyone happy to see the return of the hair accessory. The soft knit ponytail holders come in a set of five—one for each day of the school (or work) week.

Buy it: Urban Outfitters

7. D&D Graphic T-shirt; $38-$48

80s Tees

The perfect gift for the Dungeon Master in your life, this graphic tee is modeled after the cover of the classic Dungeons & Dragons rule book. It’s available in sizes small through 3XL.

Buy it: 80s Tees

8. Chuck E. Cheese T-shirt; $36-$58

80s Tees

Few Millennials survived childhood without experiencing at least one birthday party at Chuck E. Cheese. This retro T-shirt sports the brand’s original name: Chuck E. Cheese’s Pizza Time Theatre. It may be the next-best gift for a Chuck E. Cheese fan behind a decommissioned animatronic.

Buy it: 80s Tees

9. The Nightmare Before Christmas Picnic Blanket Bag; $40

Shop Disney

Fans of Tim Burton’s The Nightmare Before Christmas will recognize the iconic scene on the front of this messenger bag. Unfold it and the bag becomes a blanket fit for a moonlit picnic among the pumpkins. The bottom side is waterproof and the top layer is made of soft fleece.

Buy it: Shop Disney

10. Toy Story Alien Socks; $15

Shop Disney

You don’t need to be skilled at the claw machine to take home a pair of these socks. Decorated with the aliens from Toy Story, they’re made from soft-knit fabric and are big enough to fit adult feet.

Buy it: Shop Disney

11. Goosebumps Board Game; $24

Amazon

Fans that read every book in R.L. Stine’s series growing up can now play the Goosebumps board game. In this game, based on the Goosebumps movie, players take on the role of their favorite monster from the series and race to the typewriter at the end of the trail of manuscripts.

Buy it: Amazon

12. Tamagotchi Mini; $19

Amazon

If you know someone who killed their Tamagotchi in the '90s, give them another chance to show off their digital pet-care skills. This Tamagotchi is a smaller, simplified version of the original game. It doubles as a keychain, so owners have no excuse to forget to feed their pet.

Buy it: Amazon

13. SNES Classic; $275

Amazon

The SNES Classic is much easier to find now than when it first came out, and it's still just as entertaining for retro video game fans. This mini console comes preloaded with 21 Nintendo games, including Super Mario Kart and Street Fighter II.

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14. Planters Cheez Balls; $24

Amazon

Planters revived its Cheez Balls in 2018 after pulling them from shelves nearly a decade earlier. To Millennials unaware of that fact, this gift could be their dream come true. The throwback snack even comes in the classic canister fans remember.

Buy it: Amazon

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Treat Your Feline This Holiday Season With Fancy Feast’s Cat Food Advent Calendar

Fancy Feast/Chewy
Fancy Feast/Chewy

In anticipation of the holiday season, many children and adults get to unwrap mini presents each of the 24 days leading up to Christmas day, during what's known as Advent. Though Advent itself dates back to the 4th century, the version we know today, complete with the chocolate-filled calendars, was popularized in the early 1900s. And apparently it's no longer just for humans, because Fancy Feast is letting your feline roommate in on the fun with this unique cat food Advent calendar, now available at Chewy for $23.

For the 24 days leading up to Christmas, your cat will get to enjoy a variety of different wet foods, including favorites like grilled salmon, chicken, and more. There is even a unique ornament included with each calendar featuring a cat in the shape of a heart that can go right onto your tree. (Also, don't be surprised to find your actual cat making its way into the middle of your tree; they're known climbers.)

Now while you enjoy your Advent calendars from brands like LEGO, Funko, and more, your cat will be able to join in on the fun as well. To learn more about Fancy Feast's Feastivites Advent Calendar, head on over to Chewy.

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