The Fire Ants: Chapters 7-9

Anyone ready to discuss chapters 7-9, plus the Interlude, Mundane Methods? (For those of you jumping in late, we are discussing The Fire Ants by Dr. Walter Tschinkel by going over a few chapters per week. Click “The Fire Ants Book Discussion” category for related posts.)

Chapter 7 is about the fire ant nest. The construction and shape of the fire ant nest varies with a number of factors, including season, soil type and weather.

In general, a founding colony starts out with a simple tunnel, and as the number of workers increases, the number of underground tunnels and chambers increases. Solenopsis invicta colonies dump the excavated soil onto the surface, forming a dome-shaped mound. Unlike many other ants, they actually build tunnels in the mound and utilize it, especially during the winter months.

Below is a photograph of a zinc cast of a Solenopsis invicta nest within the above ground mound of soil. This is a negative impression, meaning the space of the tunnels has been filed with zinc and the surrounding soil has been removed.

Do you think that this use of the excavated soil comes from the fact Solenopsis invicta is from an area that floods frequently?

Anyone have comments about this chapter or the Interlude, There’s Nothing Like Getting Plastered? Tschinkel is well known for his casts of various ant nests. What do you think of his idea that we need to learn more about the nest structure or architecture as a way of understanding social insects?


And I just found a video of this:

Chapter 8. Looking at fire ant territories.

In addition to the nest itself, most ants also occupy an area around their nest that is used for foraging. This forms a territory, from which ants from other colonies are typically excluded. The size of the territory is usually dependent on the size of the colony (number of workers), as well as presence of neighboring colonies. Interestingly, fire ants have extensive underground foraging trails throughout their territories

This chapter is especially useful because it discusses the methods used to study territoriality in ants.

What do you think? I am still mulling the relationship of nest tunnels to underground foraging tunnels.

Chapter 9. What fire ants eat.

Like many other ant species, Solenopsis invicta workers are predators of arthropods, scavengers and exploit whatever sweet liquids are available within their territory. We already talked a bit about whether fire ants tend aphids. Tschinkel suggests that the ants exploit extrafloral nectaries and root-feeding homoptera for sugars.

(If you were wondering about fire ants and vertebrates, Tschinkel saves that for chapter 36.)

According to a study by Tennant and Porter (1991), fire ants carry liquid food back to the nest about 80% of the time.

We tend to think of ants storing food in their social stomach, the crop, but Tschinkel reminds us that ants can also store excess food as fat, the typical animal food storage molecule, glycogen, and also as storage proteins, such as hexamerins.

Anything surprise you in this chapter?

Interlude:  Mundane Methods

Okay, I admit it. I loved this part. It made me laugh out loud, especially the part about ant hotels on page 132. Who hasn’t had their ant workers decide to move into another laboratory/building/office on a whim?

Do you have any ant wrangling tips to share?

So, how are you doing? Are you ready to move on the read Chapters 10-12, about the founding of new colonies? Or has everyone gotten too busy and/or lost interest? (I have to admit I have been distracted a bit by Army Ant Week over at Myrmecos.)


Tennant, L.E. and S.D. Porter. 1991. Comparison of diets of two fire ants species (Hymenoptera:  Formicidae): Solid and liquid components. Journal of Entomological Science. 26:  450-465.

The Fire Ants: Chapters 4-6

Anyone wade through chapters 4-6 of The Fire Ants yet? If so, let’s get started. (For those of you jumping in late, we are discussing the book a few chapters per week. Click “The Fire Ants Book Discussion” category for related posts.)

Chapter 4. A summary of the current thinking about where, when and how the various fire ants arrived in the southern United States from parts of Argentina and/or Brazil in South America.

Basically, it appears that one species of fire ant, Solenopsis richteri, was introduced to the port city of Mobile, Alabama area around 1918 and what we now know to be Solenopsis invicta showed up in the same area in the early 1930’s. At the time the two species were thought to be two color variants of the same species, and the lighter-colored Solenopsis invicta was called the “red imported fire ant.” It is interesting to ponder why the fire ants established only in Mobile, rather than in other nearby, and presumably similar, ports such as New Orleans and Pensacola.

The area of South America where Solenopsis invicta originated is also the home of several other migrant species of ants, including the Argentine ant, Linepithema humile, and my personal backyard “pet” ants, Brachymyrmex patagonicus, the rover ants.

In a way, this chapter is also about the formative years of E.O. Wilson, as well. Can you imagine the excitement/dismay of following the spread of Solenopsis invicta through your home state?

Does anyone have any more recent information to add? How about the genetic analysis of the central South American species? Are there any recent insights about the introduction/taxonomy that you would like to share?

Chapter 5. The historical spread of Solenopsis invicta and the eradication programs to eliminate it.

Time to admit a bias. I studied with W.L. Brown Jr. at Cornell, and he told about the mistakes of the fire ant eradication programs from the first week I arrived. He explained how using Mirex to kill fire ants had actually increased the rate the fire ants were able to spread. These days any pest management book or class will talk about pest resurgence, although at the time it seemed counter intuitive. How could a pesticide that killed a pest cause it to explode in numbers? Now we know that fire ants are a weedy species that thrive where other ants are knocked out, which is exactly what Mirex did. We killed the fire ants’ competitors for them.

Bill Brown wrote some of the early papers on the subject.

W.L. Brown Jr.  (1961). MASS INSECT CONTROL PROGRAMS:  FOUR CASE HISTORIES. Psyche. (click on link towards top for a free .pdf)

What do you think of the fact that Mirex was used in the 1970’s, only roughly a generation ago? Mirex is very persistant and moves through food chains like other chlorinated hydrocarbons.

Chapter 6. Where is Solenopsis invicta going in the future?

Maps are always fun.

This one is from 1982 by Strongbad at Wikipedia.

Map of the  status of Solenopsis invicta from Purdue.

In this case, the purple colors indicate establishment, green is areas that are fire ant free. Go to website for more information and yearly maps.

Tschinkel goes into quite a bit of detail about the biological requirements of Solenopsis invicta, and how that will probably limit their future distribution.

Tschinkel does not mention the effect of competing ants. Do you think that may be a factor in areas where the environment is marginal? What about Argentine ants in California? Is it going to be the battle of the South American ants instead of ant eradication by humans?

What are your thoughts on these chapters?

Let’s read Chapters 7-9 next, with the interludes. Tschinkel explores what a fire ant colony needs to survive: shelter, space and food. If you read nothing else, be sure to read the interlude, Mundane Methods on page 130.

I’m going slightly off topic. Blame it on too little sleep.

A few months ago when I first read these chapters, I had the distribution maps above and from the book on my mind.

Then I saw this map of the distribution of ADHD prevalence of treatment from the CDC (2003):

Comparing the purple areas above with the dark red areas here… I’m not saying fire ants cause ADHD… But, well, hum…. weird.

The Fire Ants: Chapters 1-3

So, how did the first three chapters go? Pretty straightforward?

Chapter 1.

In all the reviews of The Fire Ants, most centered on Walter Tschinkel’s very first sentence of Chapter 1, “I love fire ants.” What do you think of this statement? What about the attention is has received?

A few years ago, I attended a talk E.O. Wilson gave at Arizona State University. It was about ants and conservation issues. At the end of the session someone asked him if there were any ants that he disliked, basically if there were any ants he would remove from the ecosystem if he could (I don’t remember the exact wording). I remember being taken aback when he said, “Fire ants.” I was surprised for a couple of reasons. First, I thought of the fact E.O. Wilson’s career started out when he discovered fire ants in Alabama. I also thought he would consider fire ants have positive attributes as well as negative ones. I would like to know more about why he answered that way.

What is your attitude towards fire ants? Do you side with E.O Wilson or Walter Tschinkel, or fall somewhere in between? It will be interesting to see if your ideas change after reading the book. Let us know.

Any questions or thoughts about chapter 1?

Chapter 2. Taxonomy

Tschinkel covers the recent literature about Solenopsis classification, saying that it is a difficult group to study. He concludes that the days when species can be identified solely by morphological characteristics are probably gone and that a variety of characteristics, ranging from behavioral to genetic, will have to be considered to identify species.

Anyone working on Solenopsis taxonomy here? Any comments on his synopsis?

Recent paper:  JK Wetterer (2010). Worldwide spread of the tropical fire ant, Solenopsis geminata (Hymenoptera: Formicidae). Myrmecol. News 14:  21-35. (available as a .pdf from Myrmecological News).

Chapter 3: Fire ant anatomy

Everyone familiar with the specific terminology to describe ant external anatomy? Any questions?

To get the conversation started, why not leave a brief comment introducing yourself (as much as you feel comfortable) and let us know what ants you are studying or hope to study.

I’ll start:  I studied the black carpenter ant, Camponotus pennsylvanicus and the New York carpenter ant, Camponotus novaeboracensis a number of years ago. The ant I’d most like to study is the leafcutter Trachymyrmex arizonensis, but right now rover ants are what I have available.

Reading for next week:  Let’s try for chapters 4-6. It’s about 70 pages, but it all ties together. The topic is the history of the importation of fire ants into the southern United States, what was done to try to contain them, and where the fire ant, Solenopsis invicta, may spread.

(Please send me an e-mail if your comment doesn’t appear in a day or so, and I’ll try to retrieve it.)

The Fire Ants Book

Related to the last post about Southern fire ants, have you seen The Fire Ants by Walter R. Tschinkel?

You would think that a book that is over 700 pages long about a single topic, and fire ants at that, would be pretty dreadful reading. Surprise! The Fire Ants has all the elements of a great literary work. It makes you laugh, it makes you cry. Walter Tschinkel turns out to be a scientist with a talent for writing far more than just straight research papers. As E.O. Wilson says in the Foreword, “He has delivered a masterpiece.”

I have been thinking about reviewing The Fire Ants for several months, but wasn’t sure how to tackle it because there is so much to discuss. It would be a huge post.

What would you think about taking a few chapters at a time and having a discussion? Any interest?

Let me know what you think.