I'm not an ant observer, but I recently noticed ants on my sidewalk behaving in a manner I hadn't seen before.

The sidewalk is shaded by an oak tree that is dropping thousands of tiny, hard cone-like kernels about 1/8" long and slightly less in diameter. Simultaneously this tree also drops mature acorns, so I don't know whether the tiny cones are related to the acorn process or not. The ants are also very small - 1/8" or less long.

About a week ago, I noticed occasional tightly gathered 'circles' of cones - usually about 1-1/2" to 2" in diameter, and about one to three or four cones in height. Upon further examination we discovered the circles were being 'built' by the ants, and also discovered that these 'circles' were being built around dead or dying caterpillars. Some ants were continuing to build the pile - while a steady stream of others were going back and forth - presumably carrying bits of the caterpillar back to the nest. After the ants abandon the pile, there is nothing left of the caterpillar.

I suspect this is not an unusual ant activity, but since I know little about ant behavior, I'm curious about the reason for the temporary burial of the caterpillar. Are they hiding or protecting their food-source from other predators - restricting the movement of a still living caterpillar - or what?

Here are a couple of photos - the first showing the cones as they distribute when they fall, and the second shows a caterpillar in the process of being surrounded and covered.

Thanks for your help.

Dave Owen
Lakeland, FL

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Dear Dave,

As you live in Florida, we reached out to a Florida ant expert, Lloyd Davis, and here is what he had to say:

"About this ant behavior: First, the "cones" are caterpillar dung. I suspect from the color of the ants on the caterpillar that the ants are imported fire ants. I have seen fire ants bring dirt onto a glue trap to gain access to food trapped in the glue. This however looks too far fetched. Unless someone watched the process and saw the ants positioning the caterpillar dung, I suspect some other reason for their arrangement and that it is just a coincidence that the ants are feeding on the caterpillar in the middle of the pile."

In the insect world, we often call insect "dung" or waste by the name frass. This may explain why the frass is accumulating near the caterpillar as this is the source.

Red imported fire ants (Solenopsis invicta) are unfortunately common in Florida. You can see photos of them here and here.

To learn more about red imported fire ants you can read some of our previous posts including here and here.

Thank you for contacting AntBlog,
Corrie Moreau & the AntAsk Team

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UPDATE:

Hi Corrie -

Thank you for pursuing an answer to my 'ant' question and notifying me of Mr. Davis on-line response; however I'm still puzzled by a number of points that likely have been explained had I been more thorough in my question.

If the 'cones' are, as Mr. Davis says, caterpillar frass, I am astounded by the quantity, distribution, size and shape uniformity (they look very much like sub-miniature pine cones or a tiny shelled ear of corn). When I spoke of 'thousands' of the little 'cones', it was not an exaggeration. Although no longer happening, when it was the entire portion of the sidewalk beneath the oak tree (roughly 160 sf) would be littered with these 'cones' within 24 hours after the sidewalk was swept. Incidentally, the appearance of the 'cones' started about two weeks before I wrote, and stopped almost totally and suddenly a few days after my previous note. Except when there was a 'circle', the distribution of the cones was almost uniform over the entire sidewalk area beneath the tree - and oddly there never any on the sidewalk beyond the foliage of the oak tree.

I should have noted that I did personally see the ants constructing these 'circles', and there was always a dead caterpillar or other insect in the middle. It was amusing to see these tiny ants (perhaps 1/16" in length is more accurate than 'smaller than 1/8"') swinging the 'larger-than-themselves' cones to and fro as they carried them to the pile. As the 'cone-circles' grew, the cones around the pile almost totally disappeared, defining an increasingly larger 'empty' circle largely devoid of cones (the 'cleared' circles got as large as 6" in diameter from the pile center).

I'm very familiar with imported 'fire ants', and the 'circle-builders' may well be that type, although they seem smaller and darker in color than the many other colonies we constantly battle on our large lot. These ants are almost black in color - with just a hint of red, and both front and back seem to be rounded - rather than 'wasp-shaped'. The fire ants we have in our yard all have piles of excavated sand around them that continue to grow until we poison them. The small ants about which I wrote seem to live beneath the sidewalk, and I've not seen any excavated dirt or sand, although I know it must be there.

Neither my sister nor I have ever noticed this phenomenon before in the many years we have lived here. If it does happen again, I'll try to get more information and a close-up photo of an ant moving one of the cones.

Again, I want to thank you and Mr. Davis for responding to my inquiry.

Dave
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Dave,

Regarding your second inquiry, here is what another ant expert, James Trager, had to say:

"I agree that the "cones" are caterpillar frass, and from their size, would even go as far as to suggest that they were produced by some sort of oak-feeding saturniid. Leaves are not an especially nutritious food, especially tannin-filled oak foliage, so caterpillars have to eat prodigious amounts to fuel their rapid growth rates, from tiny egg to several-inch long caterpillar in just a couple of weeks or so. This explains the rapid appearance and disappearance of the frass, and why all the frass was under the drip-line of the tree. .

Fire ants almost invariably bury large items for butchering. It doesn't surprise me that, in the absence of convenient soil particle, sawdust, or what-have-you, the ants used caterpillar frass for their burying ritual. The smaller, darker description of the ants also fits for a "butchering party" of fire ants. These gatherings usually comprise mostly or only the smaller workers, which are more uniformly dark colored."

I hope this helps!

All the best,
Corrie Moreau, James Trager, & the AntAsk Team

Wow! I didn't even know your organization existed and happened upon it by accident. Anyway, while in Namibia last spring (2012) I came upon this interesting ant while in the red dunes of Sossussvlei, Namibia. I tried to identify it when I got home, but with no luck. Can you help?

Thanks very much,

Brandi

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Dear Brandi,

Thanks for your fantastic images!

The ants pictured are Camponotus detritus, otherwise known as the Namib Desert dune ant. This species is noteworthy not only for its striking appearance, but also its peculiar adaptation to the extreme aridity of the Namib Desert. You can read more about their distribution, behaviour, and unique physiology here.

Thanks for your interest!

Alexandra Westrich & the AntAsk Team

Hi!

I am Natalie, I'm in 8th grade in chicago and i Am doing science fair, I am putting ibuprofen in ants food and drink. My question is: Will trace amounts of ibuprofen affect the behavioral patterns of red harvester ants? I have both on my ant farms set up, and 15 ants in each, I just would like some help along the way so i can do a great science fair!

Thanks and hope to hear from you soon.
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Dear Natalie,

We are glad to hear that you are participating in a science fair and that you are planning to include ants in your experiment. Regarding the experiment you are planning to conduct, here are a few things to consider:

- How will you measure the behavioral patterns of the ants to see if they are different? There are many ways to do this, but you will want to come up with some way to standardize your measurements. Will it be how much food they consume and how will you determine this? How often the ants are active versus not moving for specific periods of time that you are watching them? How often do the ants engage in different behaviors between the treatments (grooming themselves, grooming other ants, etc.)? There are lots of observations you could make, just be sure to decide ahead of time what you will do. One idea might be to just spend some time watching your ants before starting the experiments to get ideas.
- To insure that you are measuring the effect of the ibuprofen, you will need to have a "control", which in your case would be a group of ants that you are not feeding ibuprofen, but otherwise are treated and fed exactly the same. This will allow you to determine if the ibuprofen is what is causing the differences.
- You would ideally also like to have multiple pairs of ants that are and are not fed ibuprofen (but I realize this may not be possible for your project this year).

We hope this helps and have fun watching your harvester ants! Harvester ants from the genus Pogonomyrmex are beautiful animals (to see what they look like up close click here).

Enjoy,
Corrie Moreau & the AntAsk Team

Hi -- I was visiting Guarulhos in Brazil recently, and I found these ants in a tree or bush interacting with other insects. I suppose they are Camponotus atriceps or Camponotus mus and the insects probably a kind of cicada. I have to send the picture to a outdoor photography magazine and I need the Latin name, at least the genus. The picture was taken at the gardens of the Cesar Palace Hotel near to the international airport. One of the photos is of what looks like to be the nest. Can you get to me information about the other insect or the plant?

Thanks.

Javier Castosa, Madrid, Spain

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Dear Javier:

First, the bad news. I am sorry to say I cannot identify the plant in the pictures.

On the other hand, from the perspective of the AskAnt Team, you are really fortunate to have traveled to Brazil, one of the most ant-rich places in the world, where even an urban hotel garden can reveal fascinating aspects of ant behavior. The ants in your pictures are a species common both in the wild savannas and in gardens of that part of Brazil, namely Camponotus rufipes. (C. atriceps is a litttle smaller, and much shinier, and C. mus is considerably smaller with whiter hairs). When their nest is disturbed, C. rufipes can be very aggressive, delivering a strong bite into which they may squirt caustic formic acid. I had one draw blood from my finger one time, when I was doing field work in Brazil! It is one of the few ants that can do this.

The ants in your lovely pictures are associated with two types of sap-feeding insects, scale insects (round and featureless, Hemiptera: Coccidae) and planthoppers (colorful and cicada-like, Hemiptera: Fulgoroidea). Both of these animals excrete excess sugar and water from their plant sap diet in the form of honeydew (melaza in Spanish). Like many ants, C. rufipes is fond of sugar, and lingers around the honeydew "factory" to gather this waste product as it is produced by the sap-feeding bugs. you could say that one insect's garbage is another insect's treasure! The honeydew bugs in this relationship are sometimes referred to as ant-cattle. The ants also defend the bugs from parasites, predators, and competing ants.

This ant is known to make a nest of cut grass, a picture of which can be seen at the link in the next paragraph. Out in the savanna, this ant may nest in low, wet areas, and its nests may be suspended among grass stalks above the saturated ground, looking something like birds' nests. As your second picture shows, the ants also use bits of grass to build structures covering their "cattle", an additional way to shelter them from enemies. Partly chewed and glued-together plant fibers used by ants for construction are referred to as carton.

Here's a post about C. rufipes at one of our favorite blogs: http://myrmecos.net/2012/06/13/answer-to-the-monday-night-mystery-camponotus-rufipes/. Another post at the myrmecos blog lists this ant as the 48th most published ant species (among over 12,000 species to choose from). Your intention to publish these photos in an outdoor magazine will make them just a little bit more well-published.

James C. Trager & the AskAnt Team



Thanks for your question, Nathalie!

It is true that ants are proportionately much stronger than we are. I don't think any human could dangle from the ceiling with 100 times his or her body weight, like the weaver ant Oecophylla pictured here. There are many adaptations that are working together to allow ants to perform impressive feats like these: hairs on their feet that can stick to very smooth surfaces, large muscles in their heads to close their jaws, and light lean bodies. Most worker ants don't have functional reproductive systems, so their strength-to-weight ratios are higher than many other insects that are weighed down with the burden of perpetuating their genes.

However, comparing the proportional strength of even the strongest humans to an ant is unfair. Even lions, tigers, and bears (oh my!) can't lift more than 10 times their own body weight, as many insects can. Some of the physics behind this is explained here. The strength of ants is "super," but it is not super-natural. It all makes sense once you know a little more about physics.

Briefly, smaller organisms will always have bigger strength-to-weight ratios, because it's the surface area of the muscle cross section that determines strength, but the volume of the animal that (all else being equal) determines mass.

Less briefly: imagine three perfect cubes, each of a different length: 2cm, 5cm, and 10cm. The 2cm cube has a cross-sectional area of 2x2=4cm^2 and a volume of 2x2x2=8cm^3. The 5cm cube has a cross-sectional area of 5x5=25, and volume of 5x5x5=125, and the 10cm cube has cross-sectional area of 10x10=100 and 10x10x10=1000. If these cubes were animals (admittedly, very strange ones), the 2cm cube could have a strength-to-weight ratio that was proportional to 4/8, while the 5cm animal's strength to weight ratio would be 25/125 = 1/5, and the largest, 10cm cube-animal would have a strength-to-weight ratio of 10/1000 = 1/100. Of course, this is an oversimplification, but I hope this helps clarify why all of the proportionately strongest animals are very small.

Although this is an ant blog, I feel it is only fair to point out that ants are not the strongest insect, even proportionately to their body weight. The prize goes to a dung beetle, which can drag more than 1000 times its body weight. These beetles are larger than any ant, which makes their strength-to-weight ratio even more impressive.

The feat of strength in which ants have beetles beat is how rapidly some of them can close their jaws. Ants of the genus Odontomachus can close their jaws at speeds of up to 230 km/hr (143mph), generating a force that is 500 times their body mass. Not only are these forces very effective at subduing prey and smaller enemies, some of them can use their jaws to launch themselves into the air. This youtube video is completely worth checking out if you like wathching slow-motion ants flail through the air. For a more dignified synopsis, one of the original articles on Odontomachus jaws is here.

I hope this helps!
best,
Jesse Czekanski-Moir & the AntAsk Team

The fate of injured ants



Petar writes us this:

I heard ants can't regenerate - Is that true? Also how much of a healing power do they have? I accidentally squished the gaster of one of my ants and he is still alive. Will it heal?

Dear Petar:

Thank you for your questions about the healing abilities of ants, which I will answer in order:
- Ants, and insects generally, do not regenerate body parts as do crustaceans (crabs, lobsters) and arachnids (spiders, etc.). Even for those animals, regeneration is largely limited to the limbs - legs, antennae, and feelers - and most importantly, is dependent on continued growth. The new structures develop under the old exoskeleton, and emerge the next time the critters shed their "skin". Since ants never molt after reachign the adult (ant) stage of their life, they do not have this ability.
- This does not mean ants are unable to heal from injury. It is fairly common to find ants walking about and behaving quite normally, with missing parts or dented or scarred exoskeletons. It is a safe assumption they were damaged in sustaining these injuries, and then healed from them. We know they can sustain some puncture wounds as well, by healing over the breech into their innards.
- The organs inside the gaster are quite adjustable in position, and can slide past one another to a large degree when the gaster is compressed. As long as those internal organs were not seriously damaged, your ant may heal.

Please note that your ant is not a he (unless it is a winged male), as worker ants are genetically female, and some even may lay eggs under certain conditions.

James C. Trager of the AskAnt Team


Hi there, having been to France recently on a University field course I noticed that there were many aphid guarding/milking ants on Broom bushes. I have a few pictures, I find this interaction fascinating so I'd really like to know what species it is.
If it helps any I was in the Cevennes region of France. I've got pictures, not terribly clear I'm afraid. Do you know of a good Ant ID key on the internet? Even to get it down to Genus level would be most useful.
Thanks,
Lorna

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Hi Lorna,

Thanks for your interest in these interactions. They really are amazing! We contacted an expert on French ants, Christophe Galkowski, to help answer your question. According to him, "ant-aphid interactions are very common in France, many species are concerned, especially in the genus Lasius." He also identified the ants that you found as belonging to the genus Formica and are most likely Formica (Serviformica) fusca. This key may be useful for identifying other ants you collected while in France.

Thanks for your question,
Christophe Galkowski, Ben Rubin, and the AntAsk Team

I'm thinking about doing a science fair project on ants. I was hoping to create a habitat for two colonies of ants and then connecting them by removing a plastic divider. Wanted to observe what the colonies would do and how it would change their behaviors finding food, etc. Also, I read that certain ants can float by linking together on top of water. Is this true? Will ants from two colonies link to survive?

Marion


Hi Marion,

We have several posts on ant farms here, and particularly this post might be of interest to you.

Almost all ant species will viciously defend their colony against ants from a different colony. This being said, once you remove the plastic divider, the two colonies would fight each other. If the two colonies are from the same species, workers usually fight one-on-one in often lethal fights and the larger colony would win. Check out this post by Alex Wild on territorial fights of pavement ants. If the ants you bring together are from different species, it is hard to predict which one would survive.

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Two pavement ant colonies fighting (Tetramorium). Photo by Alexander Wild (http://myrmecos.net/2010/09/21/the-battle-for-clinton-lake/).

To answer your second question, fire ants can link together to float. This behavior actually helps this invasive species to survive during floods and to colonize new habitats. (To find out more about fire ants read this post.) Researchers have discovered the mechanisms behind these living floats and found that ants use the buoyancy of air bubbles to float. Linking their bodies together increases water repellent activity. Here is an article on the study by Mlot and colleagues, which was published in 2011 ("Fire-ants self assemble into waterproof floats to survive floods" PNSA 108:7669-7673).

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Air bubbles enable fire ants to float. (Picture is courtesy of Mlot, Tovey and Hu, Ant Laboratory, Georgia Institute of Technology).

I hope this answers your questions!

Steffi Kautz & the AntAsk Team


Hi Ant folk:

I am interested in finding out if ants in the Myrmicinae tribe produce silken cocoons as I am trying to get hold of some samples. Do you know anyone who has Acromyrmex echinator, Atta cephalotes, Pogonomyrmex barbatus or Solenopsis invicta in culture who might have some cocoon samples hanging around (if they exist)?

Thanks for your help.
Cheers, Holly

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Hello Holly:

No ant in the subfamilies Myrmicinae, Pseudomyrmecinae or Dolichoderinae is known to produced larval silk. The adaptive significance of this fact, and the metabolic fate of their silk production genes and anatomy is not well studied (unknown?), though perhaps one of the others on our team may know more.

Mature larvae of most species in the other subfamilies normally do spin a cocoon before pupating, so those are where you'll have to seek the materials in question, I suppose.

Just wondering, how did you arrive at this particular list of species?

Best regards, James C. Trager of the AskAnt Team.

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Hi James,

Very interesting. I came across the list of ants as I have been looking for the silks genes from the genome projects. Our lab has done a bit of work on silks from Formicinae and Myrmeciomorphs in the past and I am looking to add to the dataset.

It's interesting that you say Dolichoderinae also don't produce silk as Argentine ants have also been sequenced. Do Myrmicinae, Pseudomyrmecinae or Dolichoderinae have unique domiciles? Are they weaker than other subfamilies?

Thank you for your response and I look forward to having a few more ant conversations.

Cheers, Holly

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Hello Holly:

Myrmicinae and Dolichoderinae are diverse taxonomically and ecologically, with a wide range of nesting habitats, about which no generalizations may be made. Pseudomyrmecinae are almost all inhabitants of cavities in plants, and interestingly, species in the huge genus of Formicinae called Camponotus vary in cocoon production in a way that may be interesting to you. Soil and dead and rotten wood inhabiting ones typically have pupae in cocoons, while many that inhabit the tight confines of plant stems, notably the subgenus Colobopsis, lack cocoons.

Nonetheless, I rather think that lack of cocoons could be more of a nutritional matter than a matter of where particular ants live. A diet dominated by nectar, honeydew and fruit juice, or by seeds, is low in protein, so perhaps it was adaptive for the mainly nectarivorous or granivorous ancestors of these groups to eliminate silk production in order to conserve amino acids for growth and development. Many Formicinae are evidently more carnivorous than at some of the Dolichoderinae and Myrmicinae, and at least some have nitrogen-fixing, internal bacterial symbionts that could mitigate the nitrogen compound deficiency. I hope that my making this sweeping, and perhaps wrong guess/generalization will stimulate commentary from some others, and perhaps other myrmecologists can be brought into the discussion . . .

Do let us know if you hear from them.

Regards, James C. Trager of the AskAnt Team

Aloha,

We live in Kailua-Kona, HI and have tiny, and I mean tiny, red ants inside of our home recently, and we are unsure what they are looking for, what they like to feed on, and are also wondering how to control them. We keep our kitchen counters spotless, but they are all over the counters, and while watering an indoor plant today, the soil exploded with these ants. Also, after opening the top to our coffee maker this morning, there were hundreds and hundreds of these ants inside, so it seems that they like moisture, maybe for nesting.

Any assistance you may provide would be appreciated.

Mahalo,
Tom
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Dear Tom,

Aloha! We are sorry to hear you are having an ant problem in your home and have contacted an expert on Hawaiian ants, Dr. Paul Krushelnycky, and here is what he had to say:

"Aloha Tom,

As I'm sure you know, keeping your home completely free of ants is difficult in Hawaii. You're already doing one of the most important practices, which is keeping your kitchen clean and reducing sources of attraction. But you're right that often water is the main target, especially during dry periods and in dry areas like Kona, and its hard to do much about that. Your ants are most likely one of two species: Plagiolepis alluaudi (doesn't seem to have a commonly used common name) or the little fire ant, Wasmannia auropunctata. The latter is much more problematic than the former; you've probably already heard a lot about this species in the local media. Its now widespread in the Puna area of the island, but has recently also been detected at several locations on the Kona side.

Normally I'd recommend using a sugar-water based bait, like Terro, to reduce and hopefully eliminate new and/or small infestations. However, while this is probably the best approach for Plagiolepis alluaudi and some other household pest species, if you have an infestation of little fire ants, Wasmannia auropunctata, you'll want to do your best to eradicate them before they get too established in your home and on your property. Otherwise, you'll have to deal with a species that can reach very high densities and inflict constant, irritating stings. While the stings aren't as sharp and immediately painful as the tropical fire ants (Solenopsis geminata) we have in sunny coastal areas, they can cause a persistant painful and/or itching reaction that can last for hours or in some cases days. Some people have stronger reactions than others. If you've already noticed something along these lines, then you may have little fire ants. (A close-up photo of some workers might allow an identification, if in focus). The potted plant you mention could have been the source of introduction - colonies are easily spread this way. Did you recently purchase the plant, and did this roughly coincide with your new ant infestation? If so, eradicating the colony could be as easy as drowning it in the pot, using hot water, if they are indeed nesting in the soil. But if they are nesting in other or multiple locations, you'll need to bait them to get rid of them. If they're already widespread, eradication may be unlikely.

I can address additional questions you might have, but I would also encourage you to visit the website: http://www.littlefireants.com/ Its an excellent resource maintained by Cas Vanderwoude, a specialist on invasive ants who currently works with the state and is based in Hilo (I'm on Oahu). He focuses on little fire ants, and I believe has been trying to deal with some of the Kona sites. His website has a lot of information that can help you determine whether you indeed have little fire ants, general info about this and other species, and most importantly recommendations on how to control them. Cas has been working on developing baits specifically for this species. There is also a google-based email list for discussing little fire ants and invasive ants in Hawaii in general. Instructions for signing up are on the website."

In addition you can see a list of the ants of Hawaii with high-resolution photographs for most species here: http://www.antweb.org/hawaii.jsp

I hope this helps,
Paul Krushelnycky, Corrie Moreau, & the AntAsk Team

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