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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.

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Hopefully, that answers your question at least in part.

Does anyone else have anything to add to help Mike?

A friend is building a new house and he wanted to know about the ant colonies he found in his yard.

Photograph by Bill Webster

These shiny black ants are Messor pergandei (also seen in the literature as Veromessor.) They are a type of harvester ant, which means they collect, process, and store seeds as their main food source (See previous post).

Nearby was another ant colony.

Photograph by Bill Webster

Although these ants look similar superficially to those above, on closer inspection their bodies are dark maroon-red rather than black, particularly in the mid section. They also have fine parallel grooves on their heads. Theses ants are harvesters known as Pogonomyrmex rugosus.

Although both these species harvest similar types of seeds, it is not uncommon to find them living near each other. Robert Johnson (1992) suggests that they may segregate over broad regions based on soil texture, but coexist together in regions of overlap.

Some of Bill's earlier photographs showed the ants had placed a ring of wood fragments from construction as a barrier around their colony. It would be interesting to see whether they were reacting to conspecific colonies or those of other species.

Wouldn't it be cool to have ant neighbors like these?

For more information:

Kwapich, C.L., Gadau, J. & Hölldobler, B. (2017) The ecological and genetic basis of annual worker production in the desert seed harvesting ant, Veromessor pergandei.
Behav Ecol Sociobiol 71: 110. https://doi.org/10.1007/s00265-017-2333-1 (link)

Johnson, R.A. (1992) Soil texture as an influence on the distribution of the desert seed-harvester ants Pogonomyrmex rugosus and Messor pergandei
Oecologia 89: 118. https://doi.org/10.1007/BF00319023 (link)

Johnson, Robert A. 1991. Learning, Memory, and Foraging Efficiency in Two Species of Desert Seed-Harvester Ants. Ecology 72: 1408- 1419. (link)

Rissing, S.W. (1988) Dietary similarity and foraging range of two seed-harvester ants during resource fluctuations. Oecologia 75: 362. https://doi.org/10.1007/BF00376938 (link)

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 sucked an ant up in a homemade bug vacuum and then transported it over a mile from its home.  Will it survive if I let it go?  Do they have to find their way to their original nest in order to survive?

Anon

Answer:

First of all, can a single ant make it on its own? The answer is no, unless that ant is a queen during certain parts of her life cycle. A single worker ant on its own doesn't have much of a chance of survival.

So, could the ant navigate back to its nest if displaced? Different ants use different cues to navigate when outside the nest. Some ants can use cues from polarized light or the position of the sun. Potentially an ant that uses visual cues might be able to re-orient itself over short distances to find its nest.

On the other hand, some ants rely heavily on chemical trails to move back and forth to their colony. Think of army ants, some of which are blind. In that case, the ant would have to wander around until it accidentally ran across a trail. The likelihood this would happen decreases with distance from the nest.

At the distance of over a mile, the chances the ant will be re-united with its nestmates are non-existent. There's a tiny chance it could join a nearby colony, but it is not likely.

What about a flying insect, like a honey bee? Honey bees would stand a much better chance. They have been shown to be able to fly up to five miles from their hive while foraging. They navigate by visual cues. An experienced forager bee might be able to re-orient from a greater distance than an ant on the ground could.

Please let us know if you have any further questions.

Anyone else have any thoughts?

 

Photograph of ant in a bug sucker by Karen Gibson, used with permission.

4

A reader has a problem identifying his honeypot ant queens. Anyone out there good at Myrmecocystus identification? See the links for his photographs.

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I have an ant question! (With photo links!)

Hello there!
I recently captured a few queen ants during their nuptial flight this past August and I would like to know what species of ant this ant belongs to.

A little background information. I live in the Mojave desert, in the most Southern part. I am at an elevation of about 4,000ft and in the transition habitat between pinyon/juniper and pine. The workers are yellow/orange and are nocturnal. I’ve seen these ants feeding on nectar and small insects. Their nuptial flight took place at dusk after an afternoon thunderstorm.

Anyways, I think this species is a Myrmecocystus mexicanus, but a few others have mentioned that they are either M.testaceus or M.navajo. I’m so confused because all three sub species look the same! Here are links to two photos. Any information will be greatly appreciated! Thanks.

http://i344.photobucket.com/albums/p330/jimbodw07_2008/DSC_0001.jpg

http://i344.photobucket.com/albums/p330/jimbodw07_2008/96640104.jpg

_______________________________________________________________________

My suggestions:

As we discussed, you might want to wait until the workers come out.

If you have a good microscope and some knowledge of ant anatomy, AntWiki has a key to Myrmecocystus, to species level (both queens and workers), as well as general information about the genus

Some other useful links:

Navajo Nature has taxonomic information for Myrmecocystus

Alex Wild has photographs of various species

BugGuide has some photographs of Myrmecocystus queens, too

Does anyone else have any other suggestions? If so, please let leave a comment or contact me via wildaboutants (at) gmail.com. We'd appreciate it.

honeypots-hanging
Honeypot ants have a replete caste for storing food.