August 2010 Archives

Dear AntAsk,

I have a strange question for you. I am an American living in Austria and my Austrian friend says when an ant is crawling on you and you feel an itch afterwards that the ant has peed on you. I thought ants were biters. Do you know which is right?



This is actually a really interesting question. Ants don't technically pee: they excrete their metabolic wastes through their digestive tract, rather than through a specialized urethra. However, there are many other fascinating compounds that also come out of the back end of an ant. Many of these vary by species, and most are used in communication and/or defense. Many ants have a stinger, which they use to puncture the skin or exoskeleton of their enemies and pump poison into them (after all, ants are closely related to bees and wasps). The most painful experience you could have with an ant is getting stung by one. Some can do a little bit of damage by biting (especially very large ants like Camponotus gigas) but most ants combine biting with stinging or some other chemical defense when they are hunting or defending themselves.

Many ants do not have stings, and rely entirely on chemicals that they can secrete or spray instead. One of the most common and obvious of these chemicals is called formic acid. Formic acid is sprayed out of a specialized nozzle at the back end of ants in the subfamily Formicinae. This group of ants contains the most abundant and largest ants in much of Europe (as well as North America and northern Asia). It was the probably the conspicuous, acrid smell of the formic acid from these ants that inspired the Middle English word "pissemyre." The second part, "-myr," ultimately comes from Greek for "ant" (someone who studies ants is called a "myrmecologist"). I don't need to explain what the prefix "piss-" means to any Americans, I'm sure. I still think formic acid smells more like vinegar, but perhaps the Middle English wanted their name to be funnier.

As to whether or not formic acid, or any of the other defensive secretions other ants might use would make your skin itchy: I suspect not. I know it doesn't make my skin itchy, although it does make me cough if I accidentally inhale it. In fact, a German colleague mentioned that many people in his native Bavaria think that formic acid is good for the skin, and go to somewhat ridiculous lengths to encourage ants to spray them. It does sting slightly when it is sprayed in an open wound, of course, so ants that are really trying to inflict harm will bite you and then spray acid in the wound. Also, I suppose it is theoretically possible that someone might be allergic to something that ants secrete.

However, in practice, I suspect that the majority of people who feel itchy after an ant walks over them are just the victims of their own imagination.

I hope this helps!

Jesse Czekanski-Moir & the AntAsk Team


I have these ants in my kitchen in West Texas (Alpine). They appear
in the evening, have the run of the pantry, garbage, and countertops
and seem to disappear during the day. There used to be just a few but
now they are everywhere. They never get into food I can see - they
just do what the ant in the picture is doing, seemingly eating

What are they, and how do I get rid of them?

I appreciate your help.

Camponotus fragilis


Great picture, and great question! I think they look like Camponotus fragilis, a common species in the Southwestern US. As for some hints at how to get rid of them, we've outlined a general approach in a previous blog post (click here). If you decide to poison the ants, you might consider trying to do a quick "cafeteria" test to see what kind of bait you should mix with. Simply line up a few drops (liquid foods are preferable because you can mix them evenly with the poison) of different kinds of food on some wax paper, and see what the ants go for. I often try peanut butter, fake maple syrup, and pureed tuna fish (but perhaps see if they go for the peanut butter or maple syrup first, because pureed tuna fish can get kind of messy!).

But don't forget to try to figure out how they're getting in, and block off the entrance. If more ants keep getting inside, you won't be able to solve the problem with poisoned bait.

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

Dear AntAsk Team,

I live in southern New Mexico, (Las Cruces) and I have an odd little infestation of ants. Only in my bedroom, only in one little spot. I don't know how or where they are getting in, because they don't travel in a line. They are small and black. I did my own research, and can't decide if they are crazy ants or little black ants. Is one or the other more common here? How do I get rid of them? I honestly don't care if they are outside, since I can't find their nest anyways, but I don't want them in my room. I don't have a magnifying glass, so I can't see their nodes or antennae.

Please help me figure it out! Some are pretty tiny, but I'd say one out of five of them are significantly bigger, yet still small. I only ever get between 12 and 20 at a time, and only in one small spot in my bedroom. Can't find nests outside, can't find a line....But they are starting to take an interest in exploring my bed, and I am NOT ok with that, lol.

Thanks, Leah

Dear Leah,

Thanks for your question! Your observation that some workers are significantly bigger that others is very useful: there are some ants that have a worker caste that comes in two distinct sizes--we call those species dimorphic. Pheidole is a very common genus in many different habitats in North America that is dimorphic. Members of this genus are nicknamed "Big-Headed Ants," because the large worker caste have enormous heads. See for yourself!
Although it is glaringly obvious under a microscope, their big heads should be visible with the naked eye (if you look very closely, and if you have good eyes).

If the heads of the larger ants don't seem ridiculously huge, then it is likely that you have a member of the genus Monomorium. The members of this genus usually have workers that vary continuously in size, from large to small, but they usually travel slowly in distinct lines.

Crazy ants (this name usually refers to ants of the genus Paratrechina or Nylanderia) don't have workers of multiple sizes. However, if a worker drinks a lot of sugar water (or other sweet substance, or just plain water), the last section of their body (gaster) will become noticeably larger than other parts. So do your ants have big heads or big gasters?

Other common and very small, black ants include some members of the genera Solenopsis and Tapinoma, but these ants generally don't have works of different sizes.

As for how to get rid of ants in your room, we have some general tips in a different post, here. Please email us back if you don't have any luck, and we'll try and offer you some more advice.

Jesse Czekanski-Moir & the AntAsk Team

The ants we want to Identify are about 1/2" in length. We are in central Illinois.  They are living in an old pile of wood planks.  They are black, red, gray  (head, thorax, abdomen). Any help would be great. 
Jacksonville, Illinois


Thanks for your question! Although a picture would help to give you a positive identification, it is likely that you are looking at a member of the genus Camponotus. Members of this genus will typically be among the largest ants encountered in North America and Europe (and many other places; in Southeast Asia they have a truly giant species, see a previous post on giant ants ). These ants often live in rotting wood, including wood that has fallen, and rotten sections in living trees. Some species even live in rotting sections of people's houses! The ants commonly called "Carpenter Ants" belong to this genus, but the species in your area that lives up to this name, Camponotus pennsylvanicus is all black, so it's likely you're looking at a species that prefers the habitat in which you found it.

Based on your location and the description you gave, a likely candidate is Camponotus chromaiodes . But we encourage you to brows the Ants of Illinois page and the Ants of Missouri page to see if you can find a better match!

Hope this helps! You're welcome to send us pictures if you want a more positive identification, or if you have any further questions.

Jesse Czekanski-Moir & the AntAsk Team

Dear AntAsk Team,

I live in a suburb of Boston, MA and have noticed an increasing number of ants travelling through my garden. They seem to be going to a food source and bringing it back to their dwelling. Since they are clearly on a mission, I try to avoid stepping on them as I cross their path. All has been fine until today, when they began climbing onto my foot and biting me as I attemped to water the garden. I live in a zone with freezing temps in the winter, and an unusually hot spell this summer (with temps in the 80's and 90's daily). The ants are reddish-brown and no larger than a centimeter. There is a constant flow of them in both directions as they commute to and from their destination. I don't know where they nest nor where they go. How can I find out what type of ant they are and whether they are known to be an aggressive species? I have a "live and let live" philosophy, but I don't wish to get bitten when I go out the front door.


Good Evening,

I live in Reading Massachusetts and recently found some red/orange ants with a black gaster (back end) that run very fast around my lawn and walkways. I've had a few crawl on my leg and they haven't bitten me as of yet. This is the first time I've seen this and when my wife called the exterminator he said to spread some of the lawn granules and that should kill them.

I was wondering if you could help me identify them so I can figure out what they are and how to best treat and prevent them from taken over my yard and hopefully not my home. If not, can you help me with some other resources or companies that might be able to help me identify what type of ants they are?

Thank you for your help and support,

Dear gsonder and David,

It sounds like you might both be seeing the ant Formica exsectoides. Alexander Wild has some beautiful pictures of these ants that might be helpful in identification. A great book for help identifying ants in Massachusetts is Fisher and Cover's Ants of North America. You might also want to check out the ant section on the Massachusetts Audobon Society's website ( for some more information on your local ants.

Ants are generally great to have around the yard as they are an integral part of the ecosystem and can help clean up other dead organisms and plant debris. However, nobody wants them in their house or on their legs. For advice on keeping ants out of the house check out this post
As for the ants that bit you, it is certainly possible that the recent heat wave has increased their energy level and made them act more aggressively. Ants are not generally aggressive towards people so it was likely an isolated incident and if you avoid their foraging trails they will probably leave you alone. Unless they become a consistent or painful problem I would suggest leaving them to help clean up your yard.

Ben Rubin & the AntAsk Team

Dear AntAsk Team,
We have what I wanna say are fire ants under our house. Well my question is around the ant hills the are strands of what I wanna call silver they look like fibers of silver could it be possible that it is silver?

Texas, USA

Dear Bobby, 

When ants are digging their nests, they'll put most of what they have to dig through on top, that's what makes the ant "hill."  So it is possible that if there were something that looked like a short, silver fiber buried where they were making their nests, the ants might bring it to the surface.  There is nothing known about Fire Ants (or any other kind of ant) that would suggest that you are seeing silver threads.  But then again, there's nothing that would make it impossible, either.  

The best way to determine if it is silver would be to test it yourself.  There are a few different websites that describe easy ways to test for real silver, like here:
Hope this helps! 
Jesse Czekanski-Moir & the AntAsk Team

I just read your answer regarding "social carrying" by ants, but it doesn't explain what I think I am seeing. I have often seen ants picking up and carrying away the bodies of dead ants. It's almost as though they are acting as morticians. I've never seen what they actually do with the bodies. Is this a type of behavior that is normal, or am I being fooled into thinking that the ants being carried are dead when they are actually still alive? I have been waging a never ending war with the Argentine ants that have apparently taken over the inside of the walls in my house; and my backyard and the wall around my house and on and on and on throughout the entire neighborhood...... I've tried virtually everything to get them to leave but quite frankly over time I have found their behavior absolutely fascinating. You might say I have an ant farm with about a half a billion members. At any rate, do they actually have a job like a funeral director?


Thank you for sharing your observations with us. Ants are really fascinating with elaborate behaviors and what you are observing is hygienic behavior. The ants want to carry away the dead nestmates and dump them somewhere far away from the colony. The reason is simple: If the ant had died from an infection, the risk is reduced that more nestmates will get that infection when the body is removed. There is a really great YouTube video on the life cycle of an entomophatogenic fungus (entomopathenogenic means pathogenic to insects from the Greek ἔντομος, entomos = insect). In this video you also see a short passage of an infected worker being carried away.

Leaf cutter ants and other ant species have special areas where they deposit dead bodies, these areas are basically graveyards. Leaf cutters nest in the ground and the higher evolved species have a very elaborate tunnel system with specific chambers for different purposes. Among these chambers are dumps and with the heat produced by the composting process, the entire system gets ventilation. A really amazing YouTube video on the nesting system of leaf cutters can be found here.

All these observations tell us how cool ants are and that the many different ant species all have some really fascinating peculiarities. Keep contacting us with your observations on our blog if you want to find out more about what the different behaviors could mean.

Steffi Kautz & the AntAsk Team

I am currently living in Costa Rica; I did a quick search after witnessing the following but could find no information. On our back porch we noticed a group of ants running around in a circle for hours. There were quite a few of them and there was a bunch of live ants stuck in the center of the circle. They were going that way for over 5 hours with the circle getting bigger than a large donut. I think they were going clockwise. What's up?

Dear Niamh,

Since you are asking about a very interesting and odd behavior in some ants from Costa Rica, we called in our colleague Dr. John Longino who is an expert on ants from Costa Rica. You can check out his really great website here. Here is what Dr. Longino said:

"Interesting observation! I have never seen anything exactly like that. Army ants can stream across a porch for hours, but usually in one or multiple directions. They are blind and tend to follow each other, so theoretically they could get caught in a closed loop by accident, like Fabre's famous processionary caterpillars (there is filmed version of this in the movie Microcosmos), but I have never seen it actually happen. Another possibility is a colony of some other ant that has been flushed from its nest by army ants or somehow disturbed, resulting in an evacuation of the nest. I have seen this, with a large number of workers carrying brood waiting in a group on a big leaf or on a wall (could be a patio). There may be workers on the periphery of the group that are more active, patrolling the border. But what I have seen is just irregular motion, not coordinated movement in a circle. A third possibility is ants recruiting to food (e.g. a dropped bit of jelly). Workers in the center can be motionless at the food, licking up fluids, while other workers patrol around the periphery. But again, these ants around the border are usually moving irregularly, not in a circle, and some ants are coming and going."

Also, see this video for a potential explanation:

John Longino & the AntAsk Team

Dear AntAsk:
Recently I have been thinking about creating my own very large formicarium. I have drawn up some designs that would make my formicarium nearly 7 ft wide by 4 ft tall and roughly a 3/4 in deep between 2 pieces of glass. I'm wondering if I am merely setting myself up for failure if I go ahead and build this or if this could actually be successful? If this would work what recommendations would you make about keeping this setting moist? Also what would be the best species of ant for a situation like this? I would want a species that could burrow fairly deep.
Thank you for your time.

Dear Eric,
Thanks so much for your question!
The potentially cool thing about building such a large formicarium is that it is a closer approximation of the amount of vertical space in which some ant species build their nests. In many places the soil in which ants build their nests is not evenly moist, but has different temperatures and levels of moisture at different depths. Some of the ants that build very deep nests do so partially to give themselves a range of environmental options. Once the colony has matured and the nest has reached a large size, the ants can migrate vertically to find the "sweet spot" with the right conditions for storing their food, for example, or raising their young. Ants that live in large nests often have to adjust their positions within the nest depending on when the last rain was, and the time of day. For example, they might move their larvae close to the surface of the ground in the early morning, but then if it becomes too hot, they will move their larvae down lower. If you were to have large colony in a structure like the one you propose, you might not have to worry too much about keeping all of the substrate at the exact same temperature and moisture level, because the ants will have the freedom to find the best microenvironments to suit their different needs. Giving the ants options, by presenting them with a range of environmental conditions within the formicarium, will be the best way you can make them feel at home.

One researcher in particular, Dr. Walter Tschinkel, has studied ant nest architecture extensively. His website is really cool:
One of the things that he is able to study in the wild is which chambers the ants use for what (food storage, caring for larvae, trash, etc.). By building a large formicarium, perhaps you'll be able to make your own observations about how the ants use their space!

The one tricky thing is that you'll probably start out with a very small nest, or even a single queen, so you will need to maintain the correct conditions for the particular place within your large formicarium where the nest begins. This might be easier if you section off a small portion of the formicarium with a substance that can later be removed, or just chewed through by the ants. Rolled-up wax paper comes to mind.

A different approach would be to use the cool-looking blue gel sold in the pre-fabricated AntWorks formicaria. This substrate has gained some popularity in large formicaria meant for display, like those shown here. However, there are some anecdotal reports that the substrate does not allow ants to successfully raise their young, in part because, as we mentioned above, ants that build large nests are used to having options. The ants most likely to thrive in this gel might be ants found in environments that are very wet all the time, like tropical rain forests. Ants from dry and/or temperate regions are likely to find a uniformly moist substrate quite oppressive. Thus a giant blue gel formicarium might not be the best long-term approach to keeping an ant colony, but it is difficult to imagine a more eye-catching substrate!

Be in touch, and definitely send us pictures of the formicarium when it's completed!
Jesse Czekanski-Moir & the AntAsk Team

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