August 2013 Archives


I found some ants in my back yard that had some eggs. So I gathered a pile of workers and eggs. I couldn't find a queen though. I've heard that when you catch eggs, and no queen, the workers will raise some of the eggs into queens. I was wondering if that was true, and what do I need to do to ensure a queen is hatched.
Thanks, "CatPlip"

Dear Cat:

A point which needs to be clarified regarding your interesting question is, 'What do you mean by eggs?' To most people, anything pale-colored that the ants carry around when their nest is disturbed is their "eggs". But ants are like butterflies, in that they develop from very tiny, true eggs into legless and helpless but voracious grubs (larvae). The larvae grow to many times the size of the original egg on the protein-rich diet provided to them by the adult ants. When full grown, the larvae cease to feed, and develop into pupae, the equivalent of the butterfly chrysalis. In some ants, the pupae are enclosed in a cocoon, but in most, the pupae are naked, as in this excellent image of ant development from the myrmecos website. Lastly, the pupae develop into adult ants, whether queen, worker, soldier or male.

Now to your question: There is still much we do not know about what determines whether a particular ant egg develops into a queen or worker. It is known that in some species, workers lacking a queen can raise eggs or very small larvae into winged queens. The problem then is that these queens are not mated, so they can only lay unfertilized eggs. There is the further complication that the winged, virgin queens may not even mate, even if males are present, and thus will not lay eggs at all, until they have completed the full cycle of leaving the parent nest for a mating flight, breaking off their wings, and establishing a small nest of their own. So in essence, the answer to your question is that you cannot count on the queenless workers and brood you have collected to raise a new queen. This is why those who keep captive ants prefer to either collect whole colonies with queen or even better, to collect young, newly mated queens that will rear their own first workers in captivity, if properly cared for. These seem to adjust better to captive conditions than do mature colonies

James C. Trager of the Ask Ant Team


On August 18, 2013 while visiting a naturally restored area of Orland Park, my wife and I witnessed an ant "march" from under the base of a tree, across a parking lot, into another spot, east of the tree, filled with bushes and plants, which is near a pond. We approximated the observable distance at 120 ft. with ants covering an area about 12 inches wide. By counting the ants in the photographs we took, then doing some calculations, we estimated there were about 4,700 ants.
We observed this process for an hour and a half, as they went to wherever their "end place" beyond our field of vision in the underbrush was, to all ants returning to their original hole under the tree. They were not carrying anything visible in either direction, but we did observe them stop periodically to touch antennae. The ants on the "march" were red, with three yellow-gold lines, over a whitish area on their abdomens, and not larger than 1/2 inch. Around the "nest site" were numerous small holes and a couple larger entrances which were guarded by black ants that looked identical in size and also had similar, but less pronounced color on their abdomens. In addition, there were smaller, black, winged ants crawling around the nest perimeter. During the return to the main entry hole, black and red ants periodically touched antennae
This behavior was fascinating to observe, but puzzled us as there did not appear to be a "hostile takeover" by another species and no food was brought back to the nest.
What explanations could be offered for this expenditure of energy?

Thanks,
Anthony

Dear Anthony:

Thanks for sending the detailed account, and pictures, of your observations of these ants' behavior. You saw an ant species that has long been known as Polyergus breviceps. A little bit of nomenclature housekeeping - It turns out that this name has been applied to several different, closely related species, and the ants you observed used to be, and will soon again be officially know by the name Polyergus mexicanus, a widely distributed western North American species originally named over 100 years ago, on the basis of specimens collected in the mountains of Mexico. This ant is near the northeastern edge of its geographic range in Illinois.
What you have observed is a (failed) brood-robbing raid of these so-called slave-maker ants. Most of the time, when such a large party of Polyergus heads out as you saw, they end up at a nest of the black ant species, Formica subsericea, enter, and steal hundreds of their brood. Each Polyergus worker returns to its own nest with a pupa, or less often, a full-grown larva. Back home, the black ants already there in the nest mound, raise the young, along with the Polyergus brood. Eventually, the stolen brood emerges as adults having no knowledge of their species identity, and thus incorporated seamlessly into the work force of the mixed species colony.
The mixed species nest is that of the Polyergus, i.e., their queen and brood are there, and only workers of the "slave" species live there. Polyergus workers are highly adapted to a parasitic lifestyle, experts in acquiring host species workers, but incapable of other, normal ant behaviors such as feeding themselves, building the nest, or raising their own brood. All of these duties are performed by the Formica workers. When not out raiding with the energy and determination that you observed, the Polyergus workers remain inside or near the entrance of the nest, and in the words of the great American myrmecologist of the early 1900s, William Morton Wheeler, "sit about in stolid idleness ... begging food or ... burnishing their ruddy armor".
The pictures you sent, posted below are the Polyergus workers out on a raid, a Polyergus and Formica worker at the nest entrance, and a bonus picture of the little black, white-winged males of the Polyergus, about to head out on a mating flight in quest of virgin Polyergus queens.

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We have red ants in our yard with big barren earth mounds. Do they close them up at night? I didn't see any openings this morning and one lone ant stemmed to be wandering around the hill..it was very hot yesterday and cool this morning so I was wondering if they close the openings at night or in extreme weather

We live in Brighton Co., out on the prairie.

Judith

Dear Judith:

I'm going to take a guess here and presume you mean (out of the several Brighton Counties in the US) the one in Colorado. The most likely ant from your description and that location is the western harvester ant, Pogonomyrmex occidentalis. These ants forage in the daytime, and unless it is very warm, retreat into the nest at night. And they do indeed close off nest entrances when it's cool.

In fact, many species of ants close off their nests when conditions are unfavorable, and even more common is for them to seal up holes and reduce the size of the nest entrance to reduce draftiness.

Thanks for contacting Ant Web.

James C. Trager of the Ask Ant Team