Skip to content

Do you blog about ants? Know someone else who does? Have a favorite ant-related blog you follow? Please let me know the details or add links in the comments below.

I'm going to be working on a guide to ant blogs over the next week. It will be published on another blog, and the links will be added to the list of websites, forums and blogs page here.

Also, if you are an ant researcher and have some interesting news to share any time throughout the year, let me know and I'll pass it on to our facebook page.

Thank you!

Tipping over rocks can lead to interesting discoveries.

On a recent trip to western New York, I tipped over a rock.


I found a colony of ants in the Formica fusca group. (They looked silvery, so possibly Formica subsericea, but my eyes are getting older.)

The worker ants scurried to remove the brood to safety.

Something else caught my attention. Do you see it?

Maybe it will be clearer here. Notice the workers are rushing to hide the pupae.

The cocoon on the left is probably a reproductive pupa (queen or male). It is larger than the workers and the cocoon is made of darker, coarser silk.

The cocoons on the right are worker pupae. They are the same size or smaller than the workers and made of lighter silk.

What's up with the white, naked pupa in the center?

It is the size of a worker. Conventional wisdom says whether or not a larva spins a cocoon before pupating is species specific. Why doesn't this one have a cocoon like the others?

Some suggestions:

1. Wallis (1960) and others have proposed that Formica fusca larvae must be covered with bits of debris before they can spin a cocoon. Perhaps this one wasn't buried properly and failed to spin?

2. Perhaps it isn't a Formica fusca pupa.

Colonies in the Formica fusca group are frequently parasitized or enslaved by other species. This video shows a mixed colony of Formica sanguinea and Formica fusca with a bare pupa.

I didn't see any evidence of Formica sanguinea workers in the colony I photographed, though.

Have you ever seen Formica pupae without cocoons? If so, why don't they all have cocoons? What might be the advantages and disadvantages of spinning a cocoon versus not?

References:

I. Wallis, D. (1960). Spinning movements in the larvae of the ant, Formica fusca. Insectes Sociaux. 7: 187-199. 10.1007/BF02224080.

See previous post about Formica fusca group ants.

We often see recommendations for summer reads, and although it isn't lightweight (hardcover at 328 pp), the new book  Amazing Arachnids by Jillian Cowles makes my list.

The American Southwest is full of interesting and unique arachnids. In this book, naturalist and clinical microbiologist Jillian Cowles has captured photographs over over 300 different kinds of arachnids from eleven orders found there, including some that have never been seen before. (The cover photo is by Bruce D. Taubert).

Of course we looked for ants first. They are not listed in the index, but there's a photograph of a tiny ant mimic spider in the genus Bellota on page 29. Cowles mentions that black widow spiders eat ants (page 200) and has a full page photograph of Euryopis scriptipes spider holding a harvester ant on page 201. On page 245 is a Peckhamia jumping spider that mimics ants and on page 253 there are three genera of ant mimic spiders, Tutelina, Sarinda, and Peckhamia again.

In addition to spiders, the book covers:

  • Scorpions
  • Psuedoscorpions
  • Vinegaroons
  • Short-tailed Whipscorpions
  • Tailless Whipscorpions
  • Microwhipscorpions
  • Harvestmen
  • Wind Spiders
  • Ticks and Mites

Cowles passion comes through in the text. She discusses anatomy and taxonomy for each group before delving into their unusual biological characteristics. For example, she suggests the ability of scorpions to fluoresce at night under UV light may "reflect" a way they protect themselves against the intense daytime solar radiation of the desert Southwest. Cool!

If you are as fond of or fascinated by all things eight legged as Cowles, then Amazing Arachnids is the book for you.

Hardcover: 328 pages
Publisher: Princeton University Press (June 12, 2018)
ISBN-10: 0691176582
ISBN-13: 978-0691176581

Know any children who are interested in spiders? Try one of these two adorable fiction picture books with spider characters.

Disclosures: This book was provided by the publisher for review purposes. I am an affiliate with Amazon so I can provide you with cover images and links to more information about books and products. As you probably are aware, if you click through the highlighted title link and purchase a product, I will receive a very small commission, at no extra cost to you. Any proceeds help defray the costs of hosting and maintaining this website.

There's a question for the Consult-Ant this week. (The “Consult-Ant” started on the Leaping from the Box website, where I answered questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)

Question:  I have an ant question!
I have been observing common ants foraging and wonder what range their senses have to understand their foraging tactics. Presumably they are hoping to discover a food source.
Mike.

Answer:

Wouldn't it be cool to be able to slip into a creature like an ant and experience the world through their senses?

Unfortunately, we aren't quite there yet. Scientists are making some breakthroughs in understanding how ants perceive the world, but there are still many, many questions. To make things even more complicated, it appears that different species of ants have different sensory abilities, so there isn't just one answer as to how ants' senses work.

Although ants have a variety of senses, most ants probably use a combination of vision and olfaction to find their food. Let's explore those two in more detail.

1. Vision

Without even knowing how ants' eyes work, we can see there are big differences in the structure.

For example, this ant has massive eyes.

(Gigantiops destructor Photographer: Michael Branstetter Date Uploaded: 07/20/2009 Copyright: Copyright AntWeb.org, 2000-2009. Licensing: Attribution-ShareAlike 3.0 (cc-by-sa-3.0) Creative Commons License)

This huntress has normal-sized eyes.


Army ants have reduced eyes or are even blind.

(Public domain photograph of Eciton burchelli by Alex Wild)

For ants with well-developed eyes, we would expect that since they are small and close to the ground, perhaps they can't see far. In fact, (2004) found Myrmica sabuleti ants could discriminate objects 15 cm away, but only 10 cm above. On the other hand, bulldog ants in the genus Mymecia have excellent vision and have been reported to be able to see a meter away.

How do ants use vision for foraging? Not only can they spot prey, but also according to Hölldobler and Wilson (1990) foraging worker ants can learn/remember to return to places where they found food in the past using visual cues. Researchers have found some species of ants can orient to food sources using the the skyline (Graham and Cheng, 2009), or polarized light (for example Krapp 2007, Wehner et al. 2014). So, they may see farther than we might expect.

Related:

2. Sense of smell - Olfaction

Blind ants -- or those that forage at night -- may use their sense of smell to find food. Insects detect odors largely with their antennae.

How do the antennae work? Within the antennae are odor receptors that can bind with specific free-floating molecules. When the correct molecule bumps into and binds with the receptor, a nerve associated with it sends a signal to the mushroom bodies in the insect's brain, where it is processed or identified.

From how far away can ants detect smells? It really depends on how far the odor molecules can travel. I wasn't able to find much about detection distances for ant antennae, but male moth antennae can detect female moth pheromones from 300 feet away.

What kinds of things can they smell? Zwiebel at al. (2012) found over 400 different odor receptors in each of two species of ants: a carpenter ant, Camponotus floridanus, and the Indian jumping ant, Harpegnathos saltator. Using an unusual bio-assay involving frog eggs they discovered that although the receptors were equally numerous in both species, the odors detected by the receptors were not the same. For example, the jumping ant could detect a component of anise (a spice), whereas the carpenter ant could detect an odor from cooked pork. Presumably those differences reflect differences in their biology or environment.

According to the same article, ants also have gustatory receptors, which distinguish taste (among other things). In addition, they have ionotropic glutamate receptors that can detect toxins and poisons. This can be important for seed-harvesting ants and leaf cutter ants because plants may contain toxins that will either harm the ant larvae, or the fungus that leaf cutter ants garden for food.

3. Scouting for Food?

"Presumably they are hoping to discover a food source."

Yes, when they are outside the nest, by-and-large foraging ants are looking and smelling for food. (Although a few may be scoping out potential enemies as well.)

Again, the process varies depending on what kind of ant you have. Some ants are solitary hunters. Each ant hunts and brings food back on its own, whether seeds or insect prey. In some species, special scouts search for food and return to the nest once they find it. They recruit other foragers to retrieve the food. Often the strategy will be intermediary, and depend on the size or quantity of food on a given day.

Although most ants are omnivores, what constitutes food will also vary and those differences will change how ants detect it. For example, ants that tend aphids or leafhoppers may locate potential food by smelling honeydew that has dropped to the ground under the plant where the insects are feeding.

Conclusion

The bottom line is that how an ant finds food will be limited by the range of its senses, but right now we don't have a complete picture of what those limits are. Personally, I would not be surprised if we discover that certain ants have some amazing abilities that we haven't even thought to look for yet.

_________

Hopefully, that answers your question at least in part.

Does anyone else have anything to add to help Mike?