New species for the blog: Neivamyrmex Raiding Dorymyrmex bicolor

People who go to u-pick vegetable farms usually come home with lettuce or corn or tomatoes. When I went to a u-pick vegetable farm near Phoenix, Arizona, I came home with photographs of ants, instead.

It wasn’t surprising to see numerous circular mounds with a single entrance hole in the center.

The nests are made by a common ant in the low desert, Dorymyrmex bicolor. As I’ve written previously, D. bicolor seems to prefer to nest along dirt paths or roads. The garden had plenty of those.

Here’s another nest, again with an entrance hole in the center, and covered with active ants.

The workers here were pulling out clumps of what looked like dirt. Can you see the single petiole that is characteristic of the species?

After seeing about three dozen or so circular nests like those above, I found this one.

Same rough shape, but notice anything different?

Where are all the ants?

From another view, the entrance hole is actually blocked with dirt.

Finally, I can see some ants, but those aren’t Dorymyrmex bicolor workers.

The workers exiting from this nest are uniform in color. They have a petiole and a postpetiole.  Notice anything else about them?

The Dorymyrmex worker ants from the same perspective have large eyes. See any noticeable eyes from this view?

Having no noticeable eyes is a characteristic of Neivamyrmex army ants (Note:  They do have a single eye facet, but it isn’t obvious.)

The exact species is much more difficult to figure out.

Wayne P. Armstrong found some similar Neivamyrmex near the Superstition Mountains in Arizona, which are close to the farm where I found these ants. Gordon Snelling identified Armstrong’s ants as Neivamyrmex leonardi. The ones I found could be N. leonardi or one of several similar species.

In any case, Neivamyrmex army ants resemble their larger namesakes because they are always on the move. They don’t make permanent or long term nests like the Dorymyrmex, but instead raid nests of other ants stealing the brood for food. Seems like in this case a Dorymyrmex bicolor colony was a target of their raid. Armstrong reports Neivamyrmex workers raid Pheidole nests, as well.

So, I didn’t bring home lettuce, but maybe something even better from the u-pick farm.

Have you ever seen Neivamyrmex army ants?

New World Army Ants: Horror or Hype?

Are New World army ants the dangerous killers that movies and other media suggest?

After all, look at the jaws (mandibles) on the Eciton burchelli soldier. (Photograph by April Nobile / © / CC-BY-SA-3.0, downloaded at Wikimedia) Appears fairly fierce.

So, are they really horrors?

When reading the recent review of the Antsbirds & Ovenbirds book, Ossein asked for more information about Skutch’s descriptions of the army ants. Alexander Skutch spent years in the tropical rainforests where he commonly encountered army ants. Did Skutch worry?

On page 21 of the book (link will take you directly to the page), Skutch writes of Ecition burchelli:

“These ants are not nearly as formidable as sensational accounts depict them. They specialize on invertebrate prey. Active vertebrates of all kinds readily avoid them, perhaps not without a few stings.”

He goes on to add that

Often I have continued to sit at my table and write, while army ants scurried over the floor around me and the ceiling above me.”

On page 24, Skutch makes the point that New World army ants don’t even eat dead vertebrates. He recalls a time when a dead bird fell in the path of the raiding army ants and another time a dead snake was left in the path of the ants. Both times the army ants did not consume the remains, even though they were actively foraging.

The antbirds that follow the army ants are in no danger. In this video, you can see an elusive bare-eyed antbird standing while ants run nearby. It seems more concerned about the camera than the ants.

Bottom line, when it comes to New World army ants, the fervor has been mostly hype.

Have you ever heard that villages in some areas welcome army ants into their homes for pest control? Does anyone have a primary source for to back this up?