Ants Of Daley Ranch 3

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San Diego County Ants:
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Daley Ranch Ants:  
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  Part 3  
 
  Part 4  
 
  Part 5  
 
  Part 6  
 
  Part 7  
 
  Part 8  
 
  Part 9  
Ants Of Daley Ranch, San Diego County Part 3 (of 9)

Big-Headed Ant (Pheidole vistana) at Daley Ranch

Technical Identification Of A Minor Worker

Note: I originally thought this was a species of Aphaenogaster because of the slender body with long legs and pair of dorsal spines on the propodeum. According to Alex Wild (personal communicatiion, October 2013) it is Pheidole vistana. The form of the mesosoma and the collar around the base of the head are diagnostic for this species. Pheidole has a 3-segmented antennal club, although it is slender in P. vistana. Aphaenogaster does not have an antennal club. Both genera belong to the tribe Pheidolini.

They have been called "ghost ants" because in dim light the long, thin legs of foraging minors are not seen, and the bodies appear to be floating above the surface. I have seen pieces of Nature Valley granola moving this way across the surface of boulders on Owens Peak.

Close-up view of a minor worker.


Pheidole vistana or Pheidole hyatti?

Several ant surveys in San Diego and Orange Counties have reported the closely related big-headed ant Pheidole hyatti; however, I have not found this species at Daley Ranch so far. The minor workers of P. vistana are fairly distinctive with their narrow occiput, nuchal collar and very long antennal scape.

Note: Pheidole clementensis is also reported from coastal (cismontane) San Diego County, San Clemente Island and Santa Catalina Island. It belongs to the Pilifera Group and is very different from P. vistana/hyatti.

  See Pheidole species in Pilifera Group at Borrego Springs  

Major & minor workers of Pheidole vistana on Owens Peak. This nocturnal species was fairly common on the Boulder Creek Trail at dusk during August 2015.

Pheidole vistana major worker (soldier). This nocturnal species was fairly common on the Boulder Creek Trail at dusk during August 2015.

Pheidole vistana minor workers carrying a chunk of Nature Valley granola up a vertical rock face. They exhibit a remarkable amount of cooperation when moving large objects that I have not observed in other ant colonies in San Diego County. They have been called "ghost ants" because in dim light the long, thin legs of foraging minors are not seen, and the bodies appear to be floating above the surface. Sometimes I don't notice them until I see pieces of Nature Valley granola moving this way across the surface of boulders.

On the night of 31 August 2015, a piece of bread (bagel?) was slowly moving across the paved Ranch House Road. My hypothesis for this mysterious movement in the darkness was a contingent of nocturnal ghost ants. Sure enough, the flash on my Sony HX20V illuminated this remarkable phenomenon: One major worker and 5 minor workers of Pheidole vistana perfectly spaced around the bread. They moved in a circular rotation as they crossed the road. Curiously enough, I have seen references on the Internet that state emphatically that these are strictly carnivorous, predatory ants; however, in my experience they will not turn down human food, especially Nature Valley Granola!


Pheidole vistana From Owens Peak Inside My Uncle Milton Ant Farm


Native Fire Ants (Solenopsis xyloni, S. amblychila & S. molesta)

Fire Ant Queen (Solenopsis amblychila)

According to entomologist James Trager, this is a fire ant queen (Solenopsis amblychila), a native species of the southwestern US. I also saw another native fire ant species (S. xyloni) near the Ranch House at Daley Ranch.


Native Southern Fire Ant (Solenopsis xyloni)

Note: Many of these native ant species have been completely eliminated from urbanized areas of southern California by the Argentine ant (Linepithema humile). This is particularly true in areas that are regularly watered, providing damp, cool habitats for Linepithema. Even larger, more powerful harvester ants are no match for the sheer numbers of aggressive Argentine ants. The imported fire ant (Solenopsis invicta) is another prolific invasive species from South America that might even outcompete the Argentine ant.

Native fire ant minor workers (Solenopsis xyloni) near Ranch House Road. Although they sting, these are not the troublesome, imported South American fire ant. They usually live in open areas away from people. They have been eliminated by Argentine ants in well-watered urbanizaed areas.

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).

Solenopsis cf. amblychila North Of The Salton Sea
  Native Fire Ants On Owens Peak (Solenopsis xyloni)  
Imported Fire Ants At Mira Mesa (Solenopsis invicta)


Thief Ant Queen (Solenopsis molesta)

The very small ants are known as "thief ants" because of their habit of nesting close to other ant nests, from which they steal food. In houses they are also called "grease ants" because they are attracted to grease.

Enormous size variation in queen ants at Daley Ranch north of Escondido.

  More Images Of Thief Ant Queens  

Thief Ant Worker: Smallest Ant At Daley Ranch

Minute thief ant (Solenopsis molesta) worker. This species is less than 2 mm in length, the smallest ant I have found at Daley Ranch (so far)!

Minute thief ant (Solenopsis molesta) worker. This species is less than 2 mm in length, about the length of six average-sized grains of ordinary table salt (NaCl) placed in a row. Image taken with Sony W-300 and Bausch & Lomb Stereomicroscope (see following link).

  See Bauch & Lomb Microscope & Sony W-300  


Myrmicinae: Temnothorax andrei

Two Myrmicinae Caught In Pitfall Trap 27 June 2016

Two small Myrmicine ants caught in pitfall trap: A. Temnothorax andrei. This species is named after the French myrmecologist, Ernst André. The remarkable acorn ants, where the entire colony lives inside an acorn, belongs to this interesting genus! B. Southern fire ant worker (Solenopsis xyloni). Ant identifications confirmed by Dr. Phil Ward, University of California, Davis.

Temnothorax andrei. Slightly more detail of ant "A" in previous image captured with Bausch & Lomb microscope and Sony W300.

Temnothorax andrei. Another magnified image taken with Bausch & Lomb microscope and Sony W300. One or more of these labeled characteristics rules out other California genera in the Myrmicinae, including Pheidole, Stenamma and Solenopsis. The generic name Temnothorax is derived from the Greek "temno" (meaning cut or divided), and thorax, referring to the constriction between the 2nd and 3rd segments of the thorax (mesonotum and metanotum). According to A Field Guide to the Ants of New England (2012) by A.M. Ellison, et al., this constriction is rarely apparent.


Another Temnothorax From The Eastern United States

Imagine living with your queen & hundreds of sisters all packed into a single acorn! I have yet to find a colony of these ants in an acorn. See Images By Alex Wild


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