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If you have ever watched the ants in an ant farm, you have probably noticed ants sitting around seemingly doing nothing. This leads to the question: are the ants sleeping?

Whether or not social insects sleep is a question that has gotten some definitive work in the bees. In fact, there are bees that are affectionately called "sleeper bees" for their behavior of resting on plants in clusters over night.

For example, these long-horned bees of the tribe Eucerini (named for the long antennae present on males), are often seen resting in clusters on plant stems. Other bees and even wasps have been known to "sleep" over night in flowers.

Recently, Klein et al. conducted an experiment on sleep in honey bees. They showed that depriving worker honey bees of sleep during the night, using a magnetic device, actually effects their ability to perform waggle dances the next day. Discover Magazine has an article with a brief video of sleepy bees dancing, shown here (with a sponsor ad at the end).

What about ants? Do ants sleep?

Many myrmecologists have noticed that a certain portion of ants in laboratory colonies spend a lot of time doing nothing. Blaine Cole (1986) reported that workers of the ant Leptothorax allardycei spent up to 55% of their time resting, which he called quiescent. Nigel Franks' group writes that Leptothorax acervorum workers in the nest are inactive for 72% of the time and and foragers 15% of the time (Franks et al. 1990) and that Temnothorax albipennis workers are inactive about the same percentage of time in small colonies (44%) as in large colonies (46%) (Dornhous et. al. 2009).

None of these scientists have actually gone as far as to say these ants are sleeping though.

Deby Cassill in 2009 broke with tradition and calls certain periods of rest in ants "sleep." Working with fire ants, she videotaped ants in an artificial nest. She created an artificial colony with three queens, 30 workers and 30 larvae. Checking the posture and position of the antennae, she concluded that queens sleep 90 times per day for 6 minutes per nap, whereas workers dosed 250 times per day for roughly one minute at a time. You can see a video of the set-up at the BBC Earth News.

Cassill even went as far as to label Rapid Antennal Movements (RAM) as the invertebrate equivalent to Rapid Eye Movement (REM) sleep in vertebrates. Her conclusion: yes, ants sleep.

Ant napping?

Are we ready to agree?

1. What do you think about the studies that observe ants spend a lot of time doing nothing?

My thoughts:  One thing that is immediately apparent in contrasting the honey bee studies with the ant experiments is that an artificial honey bee hive is much more "natural" than a laboratory ant nest. In a demonstration hive the bees usually have access to outside foraging, they have comb, they are going about their business as usual.The ants, on the other hand, have no soil to move, no myrmecophiles to interact with, no predators, no opportunity to move brood to optimal locations, etc. etc. It seems evident that greatly reducing the number of available tasks at hand limits the conclusions that can be made about the behaviors observed.

2. Can ants, or even insects, sleep?

My thoughts:  Seems like a reasonable idea, especially looking at the honey bee study.

3. What do you think of the "power nap" finding with fire ants?

My thoughts:  Having spent some time filming ants, I know that they are sensitive to vibrations we humans do not even notice, such as the laboratory incubators coming on and off in the room next door. I don't have a copy of the paper yet. Does anyone know whether Cassill placed her artificial nests in such a way to minimize artificial disturbances, for example, placed them on vibration dampening pads? If not, it seems possible that something was disturbing those ants to keep them awake more often than usual.

What do you think?


Barrett A. Klein, Arno Klein, Margaret K. Wray, Ulrich G. Mueller, and Thomas D. Seeley. 2010. Sleep deprivation impairs precision of waggle dance signaling in honey bees. Proceedings of the National Academy of Sciences (PNAS). 107 (52): 22705-22709.

Deby L. Cassill, Skye Brown, Devon Swick and George Yanev. (2009), Polyphasic wake/sleep episodes in the fire ant, Solenopsis invicta. Journal of Insect Behavior. 22 (4):  313-323.

Cole B. (1986). The social behavior of Leptothorax allardycei (Hymenoptera,
Formicidae): time budgets and the evolution of worker reproduction. Behav Ecol Sociobiol. 18:165–173.

Anna Dornhaus, Jo-Anne Holley and Nigel R. Franks. (2009). Larger colonies do not have more specialized workers in the ant Temnothorax albipennis. Behavioral Ecology. 20 (5): 922-929. (full text available online free)

Nigel R. Franks, Steve Bryant, Richard Griffiths and Lia Hemerik. (1990). Synchronization of the behaviour within nests of the ant Leptothorax acervorum (fabricius)—I. Discovering the phenomenon and its relation to the level of starvation. Bulletin of Mathematical Biology. 52( 5): 597-612.

To get away from the heavy book for adults we've been reading, let's take a look at a new App about ants for children.

Do you have an iPad? If not, then this post probably isn't going to mean much to you. If you do own an iPad, however, and have children who might be interested in ants, then read on.

The world of apps has been taken by storm by The Strange and Wonderful World of Ants by Amos Latteier with illustrations by Melinda Matson. You can see screenshots at the app website.

Follow your tour guide, E.O. the Ant (Okay, that bit is stretching it) through the world of ants at three different reading levels.

Right now everyone is talking about it.

I'm not an expert at apps yet, so for reviews see:

Digital storytime review

Moms with Apps

The Strange and Wonderful World of Ants is available through the iTunes app store for iPad.
Price:  $3.99
Ideal ages 7 - 12 (Middle grade)

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.

Have you heard about this? The harsh spotlight of agricultural fame has been taken off the social insects by the paper in Nature last month. It turns out that amoebae of the species Dictyostelium discoideum treat their food bacteria like leafcutter ants treat the fungi they eat. In fact, the single-celled wonders might be called "farmers."

Did you know there were social amoebae?  When levels of their "prey bacteria" get low, the amoebae gather together to form what is called a migrating slug (see video below). The clustered amoebae move a certain distance, and then form a towering fruiting body, with a thin stalk supporting a round sorus at the top. The cells within the sorus form spores, which disperse.

Be patient for the first 30 seconds of the video. The amoebae have been deprived off food. It takes a bit of time, but then they form the slug. I wonder if the stragglers that try to catch up to the main slug should be called "sluglets?" 🙂 (You'll see what I'm talking about.)

When the "farmer" amoebae are ready to disperse, rather than eating absolutely all the bacteria available to them, they leave some. The bacteria are incorporated into the amoebae, into the slug, and carried via spores to the new area. Once at a suitable location to grow, the farmers "seed" the area with the bacteria, thus ensuring a certain food supply.

Non-farming clones of the same species of amoeba, on the other hand, consume all of the bacteria in the original area. Whether there will be food where their spores land is left to chance.

A fascinating species. And thanks to SN for bringing this to my attention,

Brock, D.A., T.E. Douglas, D.C. Queller, and J.E. Strassmann. (2011). Primitive agriculture in a social amoeba. Nature. 469: 393-396.