Solenopsis xyloni (Southern Fire Ants)

Solenopsis xyloni, the Southern Fire Ant, is native to Arizona as well as much of the Southern United States. It is in the same genus as Solenopsis invicta, the Red Imported Fire Ant. While Solenopsis xyloni shares some of Solenopsis invicta's unpleasant habits, such as aggressiveness, thankfully S. xyloni's sting is not as painful.

As always, click on the small photos to get a better view.

Here is a cluster of Solenopsis xyloni nest mounds. They are concentrated mainly along the base of the rocks. The ruler is six inches long.

A close up of a nest mound at the base of a rock.

Disturbing the nest will often make the ants come out.

Solenopsis xyloni can be a number of different colors. Typically, the small "minor" workers in Phoenix are a brownish color, as in this photo.

A close up of a minor worker.

Dark minor worker carrying soil particle out of the nest.

They also come in a red and black phase, as in this photo. This ant was collected at a cactus nectary in the desert. The vertical lines are millimeters.

A close up of the previous ant's head.

Even within a nest, though, colors can vary quite a bit. The larger ant in this photo is called a "major". You can see one of the smaller minor workers below. These ants are from the same colony.

Another shot of a major with some minors. Major workers seem to be associated with mature S. xyloni nests - young nests typically only have the smaller minor workers.

Winged sexual ants, in this case a male, will frequently come out of the nest and look around for awhile. This activity increases as the time for mating flights approaches.

Solenopsis xyloni continued