Arizona Road Trip Jan-Feb 2018 Part 6
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Arizona Road Trip Jan-Feb 2018 Part 6
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    See Ant Images Taken During Jan & Feb Of 2017!       Ant Images From Jan & Feb Of 2016!  
Ant Images (2)

Gilbert Riparian Preserve

Canada Geese at Gilbert Riparian Preserve. I also found several nests of the dark southern fire ant (Solenopsis xyloni) at the preserve as well as in the Superstitions. I have numerous stings to verify they were indeed fire ants. This is a color variation of our native red and black fire ant and not the black imported fire ant (S. richteri) from South America. The BIFA was once thought to be a subspecies or color variation of the red imported fire ant (S. invicta), but it is now recognized as a separate species.

Myrmicinae: Dark Southern Fire Ant (Solenopsis xyloni)

The native fire ants (Solenopsis xyloni) in the Superstitions are very dark, unlike the distinctive red and black fire ants on Owens Peak in San Diego County.

Southern fire ant (Solenopsis xyloni), native to arid regions of the southern and western United States, and close relative of the infamous imported fire ant (S. invicta) of the eastern U.S. The latter species is native to South America and is a serious insect pest in many tropical and temperate countries of the world. This is a polymorphic species with two sizes of workers called majors and minors. The minor workers are only about 3.0 mm long (slightly over 1/8 inch). Major workers are twice as large. Although they are small they have a potent sting, especially if they get you between the fingers. When disturbed the workers exhibit a phenomenon known as "gaster wagging" where they raise and vibrate their abdomen. They are aggressive little ants, but have been annihilated in many urbanized areas of southern California by the Argentine ant (Linepithema humile). It will be interesting to see what happens when invasive Argentine ants clash with the equally invasive South American fire ant. According to "Controlling Fire Ants Takes a Group Effort" published in the July 2009 issue of Agricultural Research Magazine: "In a battle with the Argentine ant, Linepithema humile, the fire ant won 80 percent of the time." The venom in the sting is mostly piperidine alkaloids including isosolenopsin. These are single nitrogenous rings found in black pepper (Piper nigrum), wild tobaccos (Nicotiana) and poison hemlock (Conium maculatum).

Major and minor workers of the imported South American fire ant (Solenopsis invicta) from Mira Mesa in San Diego County, California. The head and thorax are a little darker than the native southern fire ant (S. xyloni). There are other technical differences beyond the scope of this article.

Raised welts between your fingers are unavoidable if you handle these aggressive ants.

Dolichoderinae: Pyramid Ant (Dorymyrmex bicolor)

Pyramid ant nest along roadside in Gilbert, Arizona.

Found this ant in pitfall trap at Coon Bluff Picnic Area on Lower Salt River. After wondering about it for several days I think it may be Dorymyrmex bicolor. I found this species in this area in 2016 (see next image).

Nest of small mound-building ants of the genus Dorymyrmex (cf. D. bicolor) along the Lower Salt River in Feb 1966.

Acrobat Ant (Crematogaster sp.) in the Superstitions

Acrobat ants (Crematogaster) in the Superstitions. The name "acrobat" refers to the flexible way that a worker holds its abdomen (gaster) up over the rest of its body.

Crematogaster californica at Daley Ranch (San Diego County, CA): The name "acrobat ant" refers to the unusual way a worker holds its abdomen (gaster) up over the rest of its body by a very flexible petiole.

Minute Forelius Ants On Superstition Mountain

Ants of the genus Forelius (F. pruinosus & F. mccooki) are similar to Neivamyrmex in size and color. They occur under nearby rocks in the Superstitions, so you must look very carefully. Under magnification they are pretty easy to distiguish: Forelius have one petiole node and eyes. The small burs are from seed heads of triangle leaf bur-sage (Ambrosia deltodea), a dominant shrub in this area.

To get an idea of how small the worker of Forelius pruinosus really is I have compared it with grains of ordinary table salt (NaCl). An average cubical grain is about 0.3 mm on a side. For their small size, these minute ants run very fast.