Tag Archives: Fire Ants

Do fire ants cause weddings?

6 Sep

aka the “Correlation is not Causation” post

chart via Google Correlate

Google search activity for “fire ant” and “wedding gift” show a strong correlation.  (via Google Correlate)

While playing with Google Correlate recently, I discovered that lots of people tend to search for the term “fire ant” at the same times when lots of people search for the term “wedding gift.”  In fact, with regards to being the search term most strongly correlated with “fire ant,” searches for a “wedding gift” rank second only to searches for “fly traps.”  (I am uncertain if this latter represents an urgent need for pest control solutions or carnivorous plants, but I wish people luck in their quest.)

What does this mean?  Do fire ant stings somehow induce people with a desire to form government-recognized pair bonds, or at least acquire gifts for such events?  Does the proliferation of wedding cake cause outbreaks of ravenous stinging ant populations?  Could the fire ants themselves be the ones searching for the perfect, tiny wedding gift?

Or, more likely, does this correlation highlight the strongly seasonal nature of both these phenomena?  I’ll let you judge that for yourself and also tell you that the answer is that last one.  In fact, fluctuations in fire ant and wedding gift searches are more likely affected by fluctuations in temperatures, weather, and times that are convenient to fly in-laws across the country.  These similar direct causes (with the exception of vacation time and airfare, which fire ants tend not to worry about) probably lead to the indirect correlations.  This is a fun reminder that establishing causality can be challenging, and statistics must be interpreted with care.

Judging by the graph of search activity, the need to deal with both weddings and pesky fire ants peaks in summer months and tapers off sharply in the cold of winter, when presumably both ants and prospective happy couples go dormant for the winter.

Other notable seasonal search terms that correlate with “fire ants”:

“Wedding gift” on the other hand tends to correlate extremely strongly with terms involving golf, for reasons I will leave to some other scientist to explore.

Advertisements

How not to kill fire ants

10 May
A colony of fire ants (Solenopsis invicta) swarms in response to a disturbance to the mound.

Never attempt to drink fire ants.

Fire ants are the little devils that we here in the south love to hate. As such, there’s a sort of popular mythology that has risen up around them and the methods for getting them to go away.  Browsing forums around the net you can collect these bits of entomological folklore by the dozens.  Some of them are useful and some… not so much.

Blow ’em up

For example, there’s the ever-popular “grits will make things explode” theory as applied to ants:

“i heard that corn meal (ya know the stuff you can use to make corn bread) is something i heard kills them, they bring it to their nest … and they eat it, but they cant digest it so they explode (not literally, i wish they did though) so they just bloat till they die.”

Leaving aside the likelihood of grits causing anyone to explode there is one gaping flaw to this “common sense” theory.  While corn grit is used as a foundation for several commercial baits (such as Amdro), the key ingredient is the poison-laced oil the ants lick from the surface of the grits.  In fact, due to a sieve plate in their mouths and a constriction in their gut, most adult ants cannot chew or swallow solid food.  Instead, this job falls to the older larvae, who chew and partially digest solid food brought to them by the workers before sharing it via regurgitation.

Ants feed the colony and the queen dies - inaccurate fire ant art

Sorry, Amdro artist, that’s not quite how it works.

Before the evolution of trophallaxis (food sharing by regurgitation) the worker ants apparently acquired their nutrition from the larvae more directly. For example, dracula ants chew through the skin of their young and drink their “blood.”

Let them eat nutrasweet

Death by explosion seems to be a popular predicted outcome of various home remedies… possibly a case of vengeful sadism in response to one too many painful bites.  Still, artificial sweetener?

“The local news put a story about using Equal sugar substitute (I think it is in the blue packages?) on ants – it makes some ants explode. So, it’s bad for people and for ants.. go figure!”

I, personally, have never managed to make ants explode (and believe me, I’ve tried*).  According to Snopes this misconception arose around the same time as a satirical article which claimed that aspartame was first developed as a pesticide before companies “realized they could make a lot more money on it as a sweetener.”  That is to say, it’s a hilarious suggestion, but not true.

Doesn’t mean there aren’t videos about it, though.

…a few explosions would improve this immensely.

Spice things up

“When I lived in Florida, I used powdered cinnamon on the the mounds that were near plants I wanted to work with. This would keep them from crawling out of that mound until a good rain washed it away, then they would come out of there again.”

I can’t speak from any personal experience of fire ants interacting with cinnamon (although one researcher found the cinnamon treatment actually increased ant activity compared to untreated colonies).  There’s another flaw in this methodology, however.

If you watch a fire ant mound you will observe very little activity of ants coming and going from the body of the mound.  In fact, few people realize that fire ants use complex networks of underground tunnels for much of their foraging activity.  A single large colony may have more than a hundred meters of underground tunnels criss-crossing its territory like a subterranean highway system, the entirety of which it can construct (or reconstruct) in under two days (See Tschinkel’s The Fire Ants).  You may have noticed lines of excavated dirt from these tunnels running along the ground after a rain.  Such tunnels allow the workers to shelter from enemies and the heat of the day as they fan out in search of food.  Workers will even sometimes partially bury or cover over food resources they find.  (This is inconvenient for the researcher attempting to count foragers visiting sugar vials in the field.)

Kill them with kindness

Speaking of sugar vials.

“Fire ants hate sugar. If you have ever tried putting out a sugar bait for fire ants, you know what I mean. They will walk a mile to avoid some sugar.”

This is my personal favorite because it is pretty much the complete opposite of true.  Fire ants LOVE sugar.  Yes, they are opportunistic omnivores, and yes, they will scavenge on almost anything made available to them, and yes, proteins and lipids are pretty essential to the development of their young, but simple sugars are tops in terms of maintaining an energetic, active workforce which promotes colony growth.  (Also applies to humans.)

“Your fire ants are different from ours. Ours will absolutely NOT go anywhere near anything sweet. They only eat protein here.” (San Antonio)

Unless your type of fire ant is, say, a completely different species of ant, it’s unlikely the underlying biology and metabolism could accommodate such a radical shift in dietary preferences.  I’ve personally sampled fire ants across Texas, Mississippi, and even Argentina with both sugar and cricket baits, and let me tell you the sugar baits are hella popular.

Fire ants even seek out natural sugar resources, such as visiting extra-floral nectaries on plants (essentially sugar glands) or milking honeydew from aphids and other hemipterans.

Fire ant on cotton leaf drinking at extrafloral nectary.

Fire ant drinking at cotton extrafloral nectary.

Poison their fields and sabotage their supplies

A few of these sugar-based fire ant prevention tips recommend spraying sugar water, or watered-down molasses across your entire property, positing that this will promote microbial growth in the soil and drive off fire ants.

“The use of molasses actually stimulates the micro organisms in the soil, and this activity will drive away fire ants, actually, any type of ant.”

“If you spray or soak their mounds with anything sugary, the decomposition process speeds up on their food supply. The fire ants know this and will abandon a mound contaminated with sugar.”

I honestly can’t answer if there might be some kind of multi-tier effect whereby increased microbes or mold could in some way affect fire ant populations.  I dug through the literature but couldn’t find any study supporting this at all.  Color me skeptical.  If you’d like to draw your own conclusions, here are the few factoids I did dig up:

  • Activity for ant mounds treated with molasses was not significantly different than control mounds at any time (Vogt et al 2002).
  • Sinzogan et al recommends spraying mixes of water and sugar or molasses over fields to attract ants and enhance their foraging activity (2006).
  • Molasses has been used to control soil nematodes (Schenck 2001).
  • Molasses treatments may be good for your plant roots (Welbaum et al 2010).

I’d say that sounds like molasses treatments are a win for everybody!  Except maybe soil nematodes and the person trying to get rid of fire ants.

Wrath of the gods

But what about more direct (and dramatic) concoctions?  Vinegar and baking soda, that old paper-maché volcano stand-by is popular as a nest drench, apparently going for the “ant Pompeii” effect:

[whoops, the previous video got taken down.  here’s a different one:]

Meanwhile, a slightly less bubbly version employs club soda:

“I read where a liter of club soda will kill three mounds of Ants pour directly on ant (fire ants) and the Co2 will displace the oxeygen and sufficate them.”

Do these fizzy products actually work?  Elizabeth “Wizzie” Brown at Texas A&M has actually studied the effectiveness of this suggested fire ant cure, along with many other home remedies.  Unfortunately, things that sound too good to be true generally are.  Of the club soda remedy Brown says, “It also claimed that the club soda would leave no toxic residue, would not contaminate ground water and would not indiscriminately kill other insects or harm pets.  Pretty much all that part was true, but what wasn’t true was that it would be effective in killing fire ants, unless of course you happen to drown a few in the process.”

Set them on fire

Some people use a gasoline drench, with or without a match.  I’m not even going to link or quote any examples because this is really, really ILLEGAL.  And it’s hella bad for the ground water, which is even more vital of a natural resource then, say, fossil fuel.  Seriously, shame on you.

Other people employ less toxic things like fire crackers and while it’s probably not a very effective tactic, it’s certainly dramatic.

This is a fire fire ant.

Unfortunately, fizzy, flaming, or not, just dousing the mound probably isn’t going to succeed in drowning, suffocating, or exploding the colony.  Fire ants are well adapted to flood conditions.  Meanwhile, the mounds themselves are only a small part of a much bigger picture.  Fire ants use their mounds seasonally to moderate the temperature of the brood and adult ants.  It’s a great way to warm up after a long chilly night.  Beneath the nest, fire ants dig long, vertical tunnels with occasional flat, round chambers for living quarters.  (Dr. Walter Tschinkel compares them to “shish kebabs on a stick.”)

Seriously, though

“I have been fighting them for 20 years now. Spent tons of money and tricks that did not work. My father even tried to Pee on them. Nothing works.”

What does work?  Commercial baits and toxic drenches can poison the ants, while applications of boiling water provide a non-toxic alternative.  Less fatal drenches may still have some effect.  (For example, orange oil was found to reduce ant activity in one of the papers above.)  Fire ants move around naturally in response to environmental pressures, so sufficient disturbance may induce fire ant colonies to put up a satellite nest or relocate, hopefully to your neighbor’s yard.

Don’t feel too bad.  They’ll be back.

*My mom has a particular anecdote on this topic she loves to tell.  While she was at the door talking to a neighbor, 8-year-old me wandered up and asked “What do we have in this house that can make an explosion?”  I then wandered back into the house.  My mother decided to cut her conversation short.  Early adventures in SCIENCE.

Fire Ant Mating Flight

1 Apr

Following up the post from last Friday, here’s is some extremely dramatic and engaging cell phone footage of a mating flight of fire ants on a stump outside our lab.

Video courtesy Collin McMichael.  And yes, that is us having an engaging discussion about why this colony has not succumbed to our regular fire ant harvests:

Alison:  That is quite the flight.

Collin: I’m taking a video.

Alison: I guess when you nest in the base of a stump nobody messes with you.

Collin: Nope, no one digs you up.

Alison: Yeah. Can’t get mowed.

Gripping stuff.

PS:  I have updated my “Things That Are Not Fire Ants” page with 4 new images and 14 new pest control companies.  Clearly I am enjoying the Google “search by image” tool.

The Sad Plight of Male Ants (revisited)

29 Mar
Dead male winged ants in pile outside ant nest after mating flight.

Drifts of dead male alates.

Last fall I came upon this veritable drift of dead male fire ants, piled up along the sidewalk outside a large ant nest.  The worker ants there didn’t seem to know what to do with this sudden overabundance of dead bodies and were piling them up in heaps at the sidewalk edge and stuffing them into sidewalk cracks.

Dead male sexual fire ants on ground after nuptial flight.

Fire ants, like many social insects, mate in nuptial flights, swarms wherein thousands of winged sexual ants (alates) mate on the wing.  Afterwards, the females drop to the ground and shed their wings and become foundress queens, seeking out a place to rear their first brood.  The males drop to the ground and die.

Male alates drop to the ground and die after mating flight.

A male ant is pretty much a very streamlined sperm delivery device.  They hatch from unfertilized (haploid) eggs, they have big muscular backs for wing muscles, and tiny heads because they don’t need much in the way of brains.  Prior to their one and only flight they also void their gut contents and fill their abdomen with air to make themselves more aerodynamic (Wilson, “Insect Societies”).  After their mating flight the males may wander briefly on the ground for a period before their body inevitably shuts down and they die.

Male alates dead at the sidewalk edge.

The female alates, however, can go on to live more than twenty years.  Deborah Gordon has data on some of her long term study colonies of harvester ants going back to 1985.  Those colonies are as old as me!

Female alate fire ant explores nest hole.

Meanwhile a foundress queen sheds her wings and seeks a nesting site.

See also:

Biting and Stinging: The Ants

1 Feb
Red imported fire ant (Solenopsis invicta) close up.

A fire ant biting and preparing to sting.

Do ants sting or bite?  I get this question a lot, and the answer I give is: “both–sometimes–it depends.”  This is the kind of helpful answer that makes me near and dear to friends and family.  So let’s break this topic down.

Most ants bite–or in other words they have mandibles (jaws) with which they can grab or pinch objects.  However, many ants are too small to effectively bite humans.  Ants are in the order Hymenoptera, and like their bee and wasp relatives, most female ants have venom and many have a stinger modified from the ovipositor (egg-laying structure).  Thus, many ants both bite and sting.

Fire ant (Solenopsis invicta) sting up close.

Close up of a fire ant stinger.

For example, fire ants first bite, grabbing hold with their mandibles, and then sting repeatedly, injecting venom into their victim.  This is why a quick swat at a biting fire ant can often remove them before they sting.  Some very small ants, such as the fire ants’ tiny relatives the thief ants, have stingers too delicate to pierce human skin.  On the other hand, some ants like leaf-cutter ants are so well adapted for biting that they no longer have a stinger.

Leafcutter ant heads used to pinch a cut closed.

Leafcutter ant heads used to pinch a cut closed (Photo courtesy P. Lenhart).

However, not all ants with venom have stingers.  Ants make use of a number of structures to spray, wipe, rub or otherwise dispense harmful chemicals.  One prominent example is the formicine ants (Formicinae), a large sub-family of ants which make use of an acidopore to disperse venom.  The acidopore is basically a round nozzle at the tip of the abdomen which ants use to spray formic acid.  Many formicines have a ring of hairs surrounding the acidopore which  can be used to help direct the spray.

Myrmecocystus (Honeypot Ant) close up of acidopore (formicidae: formicinae) under high magnification.

The acidopore of Myrmecocystus, a formicine ant.

Spraying formic acid is a very effective technique when used against many other arthropods and small animals, but generally goes completely unnoticed by humans.  However, for the myrmecologist collecting ants with an aspirator, formicines are extremely noticeable, and suction collection is often followed by a cough.  Inhaling formic acid is not fun.

A curated specimen of Myrmecocystus

Full shot of the honeypot ant (Myrmecocystus) pictured above.  The curled under abdomen is a typical posture for spraying formic acid.

Fire ants vs. Rasberry crazy ants

2 Mar

Here’s an interesting video for you of some interactions between fire ants (the invasive ant species closest to my heart) and a newly invasive ant species beginning to spread across Texas.  Rasberry crazy ants (Nylanderia sp. nr. pubens) were first noticed in the Houston area around 2002.  (For people who don’t keep up with the world of ant taxonomy, most of the genus Paratrechina was moved into Nylanderia in 2010.)

Crazy ants take their name from the way in which they run about very quickly while turning frequently.  The common name is applied to a number of ant genera.  As you can see in the video these ants are fast.  I’ve personally witnessed another invasive “crazy ant” (Paratrechina longicornis) fall into my fire ant colonies and become trapped many times.  Although they can’t climb out again and they are vastly overnumbered they’ll hang out in little groups by the water tube for days, apparently too fast for the fire ants to catch.  Trying to squish them is like playing whack-a-mole.  They also got into the sterile buffer and the coffee.

Thanks to Danny McDonald for providing the Rasberry crazy ants and helping to referee their valiant battle.  Danny is one of the few researchers working in this system right now.

Baby, Baby, Baby (Ants queens and brood)

20 Jan

Since I’m on the topic of mating flights and founding colonies, here’s a video of some fire ant foundress queens tending their eggs, brood, and young workers.

…I sort of really, really want to add Justin Bieber’s “Baby” as the sound track to this video.  Would that be too much?

Swarms of Fire Ants

16 Jan
Solenopsis invicta and alates swarming for nuptial flight.

Fire ant workers swarm defensively prior to a mating flight.

Sexual fire ants typically fly on clear, windless afternoons following a rain.  Workers open large holes in the nest, and then spread out, swarming the surrounding area to eliminate any potential threats.  Male and female alates are urged out of the nest, where they typically climb surrounding plant material before taking to the air to seek a mate.  Below are a few clips of a colony I found swarming on a sidewalk near my house.

See related:

Alates Leaving Home

A Heap of Queens

The Sad Plight of Male Ants

Queen Ants: Founding a new colony

First, Remove Cat from Ants

21 Nov

Fire Ant Treatment Step 1: REMOVE CAT (source: GotoAID)

I have updated my Things That Are Not Fire Ants page with 7+ new pest control sources.  Check it out!

In the course I stumbled across the above illustration for treating fire ant bites in cats which may be one of my favorite “fire ant” graphics of all time. Caption:

Step 1: Make sure you remove yourself and your cat from any fire ants and gently hose off ants if you need to get them off your pet.

GoToAID looks like a useful first aid resource, plus it has the added bonus of (presumably) unintentionally hilarious 3D rendered graphics.

I’m sold!

A Heap of Queens – Foundress fire ants

26 Aug

Fire ant alates pile up on a sidewalk after a rain.
We finally had rain again.  I think it has rained twice this summer.  And with the rain come fire ant queens!

Fire ants mate in nuptial flights hundreds or thousands of feet in the air.  They use environmental cues to both synchronize mating flights with other colonies and ensure that conditions are good for founding new colonies.  This means that the afternoon following a rain (particularly if it’s been dry for a while) hundreds and thousands of newly mated queens can be found wandering the ground in search of a good nest site.  (The dying males are also in abundance.)  The foundresses may start colonies alone, in groups, or even join existing colonies.  In the meantime these ants explore every available nook and crevice which may provide both refuge and a good start on a nest tunnel.

Winged sexual fire ants cluster together

A pile of newly mated fire ant foundresses is revealed from under a twig.

The alates are easiest to find in areas where they have trouble going to ground.  For instance, on a hard gravel pathway or a paved road you may turn a leaf or a stone and find a dozen queens wedged underneath.  In some cases, like the picture at the beginning of this post, I have even found piles of fire ant alates apparently attempting to hide under each other (or at least conserve moisture).  When not hiding, the wandering alates are  easy to spot due to their large, shiny abdomens and awkward, trundling walk.

Male alate (Solenopsis invicta) is predated by jumping spider following a mating flight.

A jumping spider (Salticidae) devours a male sexual fire ant.

The sudden surge in these slow, mostly defenseless sexuals (the queen’s stinger/ovipositor is modified for egg-laying) makes a tasty meal for many predators.  Don’t think a queen is completely helpless however.  I’ve personally observed a foundress with an egg clutch tear a dozen invading fire ant workers limb from limb with her mandibles alone.