Invasive Crazy Ants Are Displacing Fire Ants, Researchers Find

May 16, 2013

AUSTIN, Texas —


Image courtesy of Joe MacGown, Mississippi Entomological Museum

Invasive “crazy ants” are displacing fire ants in areas across the southeastern United States, according to researchers at The University of Texas at Austin. It’s the latest in a history of ant invasions from the southern hemisphere and may prove to have dramatic effects on the ecosystem of the region.

The “ecologically dominant” crazy ants are reducing diversity and abundance across a range of ant and arthropod species — but their spread can be limited if people are careful not to transport them inadvertently, according to Ed LeBrun, a research associate with the Texas invasive species research program at the Brackenridge Field Laboratory in the College of Natural Sciences

The study by LeBrun and his colleagues was published in Biological Invasions.


“When you talk to folks who live in the invaded areas, they tell you they want their fire ants back,” said LeBrun. “Fire ants are in many ways very polite. They live in your yard. They form mounds and stay there, and they only interact with you if you step on their mound.”

LeBrun said that crazy ants, by contrast, “go everywhere.” They invade people’s homes, nest in crawl spaces and walls, become incredibly abundant and damage electrical equipment.

The crazy ants were first discovered in the U.S. in 2002 by a pest control operator in a suburb of Houston, and have since established populations in 21 counties in Texas, 20 counties in Florida, and a few sites in southern Mississippi and southern Louisiana.

In 2012 the species was formally identified as Nylanderia fulva, which is native to northern Argentina and southern Brazil. Frequently referred to as Rasberry crazy ants, these ants recently have been given the official common name “Tawny crazy ants.”

The Tawny crazy ant invasion is the most recent in a series of ant invasions from South America brought on by human movement. The Argentine ant invaded through the port of New Orleans in about 1891. In 1918 the black imported fire ant showed up in Mobile, Ala. Then in the 1930s, the red imported fire ant arrived in the U.S. and began displacing the black fire ant and the Argentine ants.

The UT researchers studied two crazy ant invasion sites on the Texas Gulf Coast and found that in those areas where the Tawny crazy ant population is densest, fire ants were eliminated. Even in regions where the crazy ant population is less dense, fire ant populations were drastically reduced. Other ant species, particularly native species, were also eliminated or diminished.


By Joe MacGown, Mississippi Entomological Museum

LeBrun said crazy ants are much harder to control than fire ants. They don’t consume most of the poison baits that kill fire ant mounds, and they don’t have the same kinds of colony boundaries that fire ants do. That means that even if they’re killed in a certain area, the supercolony survives and can swarm back over the area.

“They don’t sting like fire ants do, but aside from that they are much bigger pests,” he said. “There are videos on YouTube of people sweeping out dustpans full of these ants from their bathroom. You have to call pest control operators every three or four months just to keep the infestation under control. It’s very expensive.”

LeBrun said that in northern Argentina and southern Brazil, where the ants are native, populations are likely held in check by other ant species and a variety of natural enemies. In the U.S. there is no such natural control.

Here the crazy ants can attain densities up to 100 times as great as all other ants in the area combined. In the process, they monopolize food sources and starve out other species. LeBrun said the crazy ants, which are omnivorous, may also directly attack and kill other ant and arthropod species.

The overall result is a significant reduction in abundance and biodiversity at the base of the food chain, which is likely to have implications for the ecosystem as a whole.

“Perhaps the biggest deal is the displacement of the fire ant, which is the 300 pound gorilla in Texas ecosystems these days,” said LeBrun. “The whole system has changed around fire ants. Things that can’t tolerate fire ants are gone. Many that can have flourished. New things have come in. Now we are going to go through and whack the fire ants and put something in its place that has a very different biology. There are going to be a lot of changes that come from that.”

LeBrun said a great deal about the Tawny crazy ants remains unknown, including their potential range. So far, most of the colonies are in fairly wet environments with mild winters, near the coast, so it may be the case that they can’t thrive in drier or colder climates, and that fire ants will remain dominant in those areas.

The spread of the Tawny crazy ants may also be limited, even within the more hospitable climates, by caution from humans. The reproductive members of the species don’t fly. So when left to their own devices, crazy ant colonies can only advance about 200 meters a year. That means they’re dependent on humans to colonize new areas.

“They are opportunistic nesters,” said LeBrun. “They can take up residence in everything from a house plant, to an empty container left outside, to an RV. So they’re easily transported by us. But the flip side of that is that if people living in or visiting invaded areas are careful and check for the crazy ants when moving or going on longer trips, they could have a huge impact on the spread.”  Nursery products also appear to be a key way these ants spread, so both buyers and sellers should be watchful for these ants.

LeBrun said that cutting down on the number of transplantation events could slow the spread by years or decades. And that extra time could give the ecosystem time to adapt and researchers time to develop better control methods.

“We can really make a difference,” he said, “but we need to be careful, and we need to know more.”

For more information, contact: Daniel Oppenheimer, Hogg Foundation, 512 745 3353; Edward LeBrun,, (512) 471-2825.

60 Comments to "Invasive Crazy Ants Are Displacing Fire Ants, Researchers Find"

1.  David Ridge said on May 16, 2013

Well, it is said what goes around comes around so what have we done this time to upset something, somewhere, somehow?

2.  Kelly said on May 17, 2013

I have these ants in my home... I hate them .

3.  Sammie Bauman said on May 17, 2013

The Crazy Ants found our house and nearly drove us crazy...everything had to be put in freezer or refrigerator..they are able to get into the pancake syrup with it cleaned and lid on tight...yes we swept up piles of the pests...ended up calling the pest control..just couldn't get a hand on them but I think we finally have them under control and yes the man found them in the attic also..Thanks for this report on them, it is very informative...

4.  Kent Brockman said on May 17, 2013

I for one welcome our new ant overlords.

5.  Wastrel said on May 17, 2013

Long-term and inexpensive control by pesticides and telling people to look for the ants in their potted plants etc. is hopeless. This was demonstrated by attempts to control the inported fire ant.

"LeBrun said that in northern Argentina and southern Brazil, where the ants are native, populations are likely held in check by other ant species and a variety of natural enemies. In the U.S. there is no such natural control." Importing other ant species (to create competition) seems unwise, but since the crazy ant is already established, we can try importing some of their natural enemies. Potentially, these are bacteria and fungi, phorid flies (like the imported fire ant), and parasitic wasps or lepidoptera. Apparently some populations of the imported fire ant are also infected with a virus.

Is there a need to spend decades and millions of dollars studying the crazy ant to indentfy these natural enemies and then introduce them to this country? No. Go to their native territory in Argentina and Brazil, and collect 50 or 100 whole colonies of crazy ants, transport them quickly to the US and let them loose in areas that are already infested. They will bring the parasites, bacteria, fungi and viruses with them. This may seem counter-intuitive but the additional harm from a few more colonies will be minimal, while the benfits of importing their natural enemies will be great.

6.  Frederick Ark said on May 17, 2013

Crazy aunts are the worst; always giving you beanie babies for your birthday.

7.  Johnny8 said on May 17, 2013

Ant Overlords?...Hmmmmmm...Jusy maybe the crazy old man down the road was RIGHT...Now...somebody help me find my fly swatter...

8.  pete said on May 17, 2013

I'm insulted they are called "crazy" ants. It should be "challenged" ants or something not so offensive. I shall write my congressperson.

9.  Geoff said on May 17, 2013

One thing that the article did not discuss (and I am too lazy to look up) is whether tawny crazy aunts kill termites. Here in southern California, termites are a very expensive nuisance and trading the damage from termites for the aggravation of crazy ants might be worth it.

And for the people afflicted with crazy ants: try borax powder. The ants around here walk over it, lick their feet, and die. It's efficient.

10.  Larry said on May 17, 2013

I bought a tree threw arbor day and live in Pa. I had what I thought was spiders with a nest and leaves curling in. The big red ants were crazy. You get within a couple feet and they'd stand on there hind legs and look like they'd pounce on you. I know they followed me while waling around them. I took one as a souvenir; tried to get it identified.... but all the nursery guys just said get it the hell out of here... even in a jar. These ants sure were crazy. Not sure what they were though. I spayed the tree and not seen them since.

11.  Hal said on May 17, 2013

I first noticed these ants at our home here in Pearland, TX (just south of Houston) a little over a year ago. I have not seen a cockroach in our house since. I've only seen them in the yard (so far) and not inside house. The only predator I've seemed to notice they have are all of the doves we have around here.

12.  Hawaiian Dude said on May 17, 2013

Don't want to use a Pesticide? Do what we do in Hawaii. Use an empty Windex bottle and fill it with very soapy water and spray it on the ants. The soapy water will wreck havoc on the ants oily bodies. Then keep the inside of your Kitchen spotless clean if you want them to stay away.

13.  steve said on May 17, 2013

We lived in Haltom City TX and had a bought with fire ants... Ouch what a sting, I moved to Antarctica (pun intended) and now I put up with those pesky penguins.

14.  Citizen A said on May 17, 2013

This article fails to mention plants that deter ants. So take a ride on your internet browser and research the kinds of plants ants hate. Humans love to resort to toxic chemicals...egads...get a grip - turn to Nature.

15.  LJ said on May 17, 2013

Crazy ants made it all the way to Cleveland! When Lebrun found out, he quit on the city and took his vast knowledge of ants to south beach.

16.  Terence Conklin said on May 18, 2013

Call me crazy but I prefer crazy ants any day. I lived for years in the Virgin Islands and crazy ants eat sweet stuff are fun to watch and relatively harmless. Fire ants sting like crazy (no pun intended) and feed on fatty stuff. I suspect they change in the environmental balance is due to crumbs of jelly donuts dropped by our billowing overeating neighbors. Switch back to Kentucky Fried and the fire ants will return to favor.

17.  Jonathan Lovelace said on May 18, 2013

Importing their natural predators is not a good idea.

There is a long and horrid history of doing that sort of thing. In short, instead of one invasive species, you have two. Google Australia cane toad, or Hawaii Mongoose, and scores of others.

18.  Texas Bugs R Us said on May 18, 2013

Call Texas Bugs R Us to rid of your crazy and or rasbury ants 713-955-2847 Houston and surroundings.

19.  Patrick Byrne said on May 18, 2013

Ha! I love the comment about being ready to accept our crazy ant overlords. That is very phunnie.

20.  Patrick Byrne said on May 18, 2013

Oh I get it...Kent Brockman's Simpson episode comment. Again, hahaha.

21.  Anteaters R Us said on May 18, 2013

We have rentals available,both Aardvarks and Anteaters.

22.  coacervate said on May 18, 2013

Eat em.

23.  One Flewover said on May 18, 2013

If they're truly crazy I say we put them all in an insane asylum and throw away the key

24.  woz said on May 18, 2013

global warming?

25.  Doug Newman said on May 18, 2013

For ants and many bugs the best thing II found to control them was Diatomaceous Earth..
I would find a trail and put out a cap full of Syrup water and then after they knew wher it was I would lightly sprinkle Diatomaceous Earth all aroud where it was and put it back again Do this in a couple of places and the coloney will quickly in a couple of weeks all be gone..

26.  zach said on May 18, 2013

time to get a pet anteater

27.  Terry said on May 18, 2013

I think some of these crazy ants have morphed into what we call DC politicians!

28.  Lonay said on May 18, 2013

Termidor , should be the answer, works well on all ants.

29.  christo said on May 18, 2013

I think that climate change is due to the crazy ants too, the ecology of Texas is in danger. Where's congress when you really need them to stamp out a pest!

30.  Yog S said on May 18, 2013

Take a look at Australian biological history for many examples on why your proposal won't work and will only introduce a whole new series of problems.

31.  Wilf Tarquin said on May 18, 2013

@Wastrel: That is a good plan. The typical pattern for an invasive species is to undergo a population explosion, and then gradually predators and parasites catch up, reducing numbers. Your plan would shortcut this process for the Crazy ant.
The downside is that since you don't know what you bring in, you could be bringing in even worse pests, but the probability in a case like this is low.

32.  Erica said on May 18, 2013

I had these crazy ants invade a laptop and crap up the motherboard! They like to move their eggs and make outposts in the craziest places! They also infested an abandoned tube of lipgloss... They come out in droves ..windex will kill them on contact.

33.  bob said on May 18, 2013

@Wastrel you're an idiot. Introducing a new species to combat a pest might seem like a good idea but as many countries have found out this only leads to more problems. The smartest way to do it is to clean up the mess ourself which is costly and time consuming but the results of another introduced species could be even more dangerous.

34.  Pete in Texas said on May 18, 2013

Look into treating infected areas with garden-grade (not swimming pool filter-grade) diatomaceous earth. It kills insects mechanically, not chemically. It is "dusted" and remains effective as long as it stays dry.

35.  Brian Baumgartner said on May 18, 2013

Crazy ants (and that's what we called them) were around our home in Pearland, Tx back in the late 1990s. I keep reading that some pest control guy "discovered" them in 2002. I guess we did not know at the time that they had not been "discovered" yet!

36.  Gary Laller said on May 18, 2013

Had a serious infestation of crazy ants as did my neighbors.

used a fine powdered product containing .1% Deltamethrin (Ultradust Fire Ant Killer )

Over 3 months hit every trace of ant infestation with a 500 yard radius of my home my neighbors used professional exterminators seems to be gone now for last 6 months.

Note found 6 blind iguanas full grown blinded but the crazy ants eating their eyes out . The iguanas sleep soundly at night. They look like they are dead and can be picked up and shaken hard before they wake up.

I do not have any infants but I would think they could also do the same with infants.

37.  CrazyME said on May 18, 2013

Find a commercial use for these little critters; say some type of food product and then we can just over-harvest them into extinction like we have for so many other species. Problem solved!

38.  Val said on May 18, 2013

It's time the Ants ruled this Earth. I salute Kent Brockman's courage for speaking out in favor of our new masters. It only goes to figure, that something with an exoskeleton would win this struggle for dominance. I wish I was an Army Ant.

39.  Val said on May 18, 2013

It seems to me if we have a crazy ant problem, we just need to get some Insane Anteaters up in hurr! Maybe like an Insane Anteater Posse...

40.  Hobby Rancher said on May 18, 2013

Wastrel, I'm in your camp, but we have to be careful we don't bring other unwanted species with the crazy ant enemies. Poisons are spot treatments. It will take a biological control to put a lid on crazies.

41.  Becca Helen said on May 18, 2013

Really would love to know which 20 counties in Floriduh they've been found. The picture doesn't help much either. I may, or may not, have seen these around my deck area, and a few in my walk-in shower. Guess I'll research it on my own. Lots of info, but geez, tell us where they are!!!!!!

42.  chuck curtis said on May 18, 2013

Where in Hays county have crazy ants been found?
I live in Wimberley.
Thank you for a response.

43.  Howard Sweet said on May 18, 2013

We had these things last year. They are the smartest insects I have ever encountered. We had a dinner party where we served turkey and ham. The crazy ants smelled it outside and that night I saw the super colony send out platoons to start investigating the perimeter of the house. They ended up joining themselves head to foot in a long living ladder and invading through the attic fan. I tried to fight them off with spray, but they would send sacrificial diversion parties to draw my attention away from the main invaders, who were going after the fridge. Once they reached it, it took them less than an hour to learn how the water dispenser worked and disassemble it. They entered the fridge through the emptied out water tube and then thousands of them cut up and carried away both the ham and the turkey. All they left was bones, clean, dry, white skeletons. Then they spray painted the walls with vulgar threats warning us not to follow them and swearing revenge for those that fell during the raid. Apparently we've been standing on the throat of the ant kingdom for too long. It's our time to pay -- mostly in lost leftovers. What a bunch of pests.

44.  Kay Whetzel said on May 18, 2013

I am a retired field biologist and understand how devastating introduced species are. Given a choice between exotics, in reality, I would prefer to live with non-biting-stinging species than ones who can kill animals and humans. Speaking from experience, I was sent to an ER from an accidental fall into a fire ant colony. However, I often am able to control invading insects - no matter the species - with a couple cans of Holiday foggers. The size of the fogging dispersal agent is so small that it creeps into all hiding places of insects and stops them for awhile. If one 'fogs' 1-2 times a month, one can eliminate colonies of anything. And, it is less expensive than pest control companies and their insecticide applications that don't always work.

45.  daixy said on May 18, 2013

@ kbrockman, best comment ever. lol. i too agree and acquiesce.

46.  Oregonerd said on May 18, 2013

Boric acid. I mix borax soap with sugar and water. Mix it correctly and they take it back to the nest with them. Works well. I don't have crazy ants but its worth a try. Google it.

47.  captainhurt said on May 18, 2013

keep it dry and clean and ants will stay away.
if you like to live where its wet and hot, then apparantly you already like bugs, and one more aint gonna bother you.
if you dont like bugs, just keep it dry and clean.

48.  Patrick said on May 18, 2013

We use Borax outside and in locations where pets cannot reach and diatomaceous earth inside and everywhere else.

With milder over-winter temperatures (no freezes) both plant and insect species susceptible to cold are growing and proliferating like crazy. Our current problem does not appear to be the Tawny Crazy ant but Carpenter Ant which bites rather than stings along with cockroaches that bite as well.

Hillsborough County, Florida

49.  Elizabeth said on May 19, 2013

Smart Wastrel!!! Just what I was thinking!

50.  Perenti said on May 19, 2013

Importing whole colonies is a bad idea if the parasites, fungi and viruses prefer native species (which won't have adapted to live with them) to the crazy ants. Biological control is very hard. Solutions that look easy are almost always terrible. We know that here in Australia, where we imported cane toads to control cane beetles. The toads preferred everything else.

51.  Rob said on May 19, 2013

SimAnt predicted this years ago...

52.  mmiddleton said on May 20, 2013

"Is there a need to spend decades and millions of dollars studying the crazy ant to indentfy these natural enemies and then introduce them to this country? No. Go to their native territory in Argentina and Brazil, and collect 50 or 100 whole colonies of crazy ants, transport them quickly to the US and let them loose in areas that are already infested. They will bring the parasites, bacteria, fungi and viruses with them. This may seem counter-intuitive but the additional harm from a few more colonies will be minimal, while the benfits of importing their natural enemies will be great."

@Wastrel - we imported the crazy ants, and they are causing a great deal of problems, so you want to import something else to see if that handles the issue? Sounds great! What could possibly go wrong?

53.  Sue T said on May 20, 2013

I live in Orlando (Orange County) and I have them. They follow no trails and really do seem to be randomly walking everywhere. I have seen them in the bathrooms, kitchen and around the windowsills. They are a very small ants. I just bought some ant bait that is designed for crazy ants and they have disappeared from the bathrooms. It contains Imidaclorpid. Boric acid does not work. I am going to put this bait outside, around the house, in the hopes their nest is outside.

54.  Paul said on May 20, 2013

I sprinkle Cream of Wheat on ant mounds. It's non-toxic, and the ants love it. Unfortunately, it stops them up and they can't poop, eventually dying off.

55.  bben2013 said on May 20, 2013

Aardvarks to the rescue? Why not release some Aardvarks into affected areas? Just a thought.

56.  Calrk said on May 21, 2013

Has anyone tried a bug zapper? If they're attracted to electrical equipment I think they would love a bug zapper.

57.  flink said on May 21, 2013

To rid your home of ants, boil several sticks of cinnamon in a pot of water for a couple of hours a once or twice a week.

58.  Plenner said on May 22, 2013

The boric acid method and (I think) the interesting suggestion of Cream of Wheat work as desiccants. Desiccants absorb water from the body of the ant, thus killing them. The suggestion of using soapy water sprayed on the critters works by dissolving the thin layer of oil on the ant's body, and thus the water in the ant gradually evaporates - again, killing it through dehydration.

59.  Nancy said on May 28, 2013

First saw them 1 ago and I literally thought they were the craziest acting things I had ever seen.

I live in Squeezepenny, TX about 40 miles north of Dallas.

60.  Jennie P. said on June 13, 2013

I'm a student reporter from UT. I'm working on a story regarding safety precautions for the influx of crazy ants. Unfortunately, I'm finding it impossible to land an interview with a specialist or anyone who's been inconvenienced by these new-aged critters! If you've been personally affected, (residential or business), or consider yourself a specialist, I'd love to speak with you!

If you'd be so kind to help out an aspiring student reporter, I assure you the interview will be quick and painless.