Disclaimer: I am reasonably certain about most of the identifications, especially those verified by James Trager, Alex Wild & Phil Ward. For some of the names I used cf. (compare with) because of the difficulty in separating very similar species. On others I simply placed the ants in their respective subgroups of closely-related species. Large, difficult genera often require a specialist for precise species verification. Although identifications from my photo images may be impossible without voucher specimens to examine, comments and/or suggestions about my identifications are welcome. Send E-Mail Message To Wayne's Word:

Linepithema humile

Most of these species were found at my residence in Twin Oaks Valley, San Marcos which is dominated by massive populations of the aggressive Argentine ant (Linepithema humile). In fact, I was very surprised to find additional ant species here, including some unusual tropical species. They were collected in pitfall traps placed along a bridle path and in the midden (graveyard) of a Forelius mccooki nest.

Like the duckweeds (Lemnoideae), ants have been renamed by taxonomists over the decades even when the species was already officially named & published decades or centuries before. For example, the name Cardiocondyla ectopia appears in a detailed USGS ant survey in Orange County just north of Twin Oaks Valley, Northern San Diego County. According to Antwiki.org, C. ectopia is a junior synonym of C. mauritanica. In other words, it is a synonym that describes the previously published C. mauritanica. For this and other morphological reasons, I am calling the Twin Oaks Valley species Cardiocondyla cf. mauritanica. Ideally I should place cf. (compare with) before the species epithet because I am not 100% certain of its ID. Some ants are very difficult to identify, especially minute species with characteristics beyond the range of my magnifying devises!

The above image of Cardiocondyla mauritanica clearly shows this species lacks the dorsal standing pilosity (erect hairs) of Temnothorax. This is a widespread species with an enormous native distribution from northwest Africa to India. It has been suggested that one of the reasons for its success in spreading throughout the Old and New Worlds is its ability to co-exist with dominant invasive species such as the Argentine ant (Linepthema humile). Argentine ants were observed to shrink back when encountering Cardiocondyla workers, suggesting that they may release an effective and potent chemical repellant.

The common name "moorish sneaking ant" has been proposed for this genus, apparently due to their inconspicuous nature. The specific epithet mauritanica is Latin for "Moorish." The term "Moor" is derived from the Mauri people of northwestern Africa, and has long been used in Europe as a colloquial term for inhabitants of North Africa. When viewed from above, the postpetiole is much broader than the petiole and is roughly heart-shaped, hence the generic name Cardiocondyla.

Compared with most tramp ants, the colonies are relatively small with a few hundred workers and multiple queens. Many ant species exhibit polymorphism in workers, with different sized minor and major workers. Cardiocondyla has polymorphism in males, a rarity in ant species. This condition is technically termed polyphenism: Two or more distinct phenotypes are produced from the same genotype, a compelling reason to study epigenetics! In Cardiocondyla there are winged males that leave the nest to mate with winged queens (alate females) from other colonies, and wingless fighter males that mate with female sexuals (queens & workers) within their natal nest.

Cardiocondyla wingless fighter male showing sickle-shaped mandibles used for killing other wingless males in nest. Docile winged males are not harmed. Image from Jürgen Heinze (2016). More Images In Article By Jürgen Heinze

This small ant is about 2 - 2.5 mm in length. It belongs to the subfamily Myrmicinae (tribe Attini) and includes the larger Arizona leafcutters Acromyrmex & Trachymyrmex, and the tropical leafcutters Atta. Like the larger leafcutters, Cyphomyrmex is a fungus-gardening ant. It carries organic material such as insect droppings and pieces of plants back to its nest, using the material as a food for their fungus gardens. The ants then eat the fungus that they cultivate on the debris.Their garden consists of a particular fungal species that these ants have been cultivating for millions of years!

According to AntWiki.com this species was foraging in the leaf litter along the path at the Arizona Sonora Desert Museum on an overcast day. They were quite small and difficult to see. All Cyphomyrmex species cultivate badisiomycete fungi in the tribe Leucocoprineae. In the rimosus group of attine ants, most species grow fungi in a yeast form (small masses of unicellular fungal cells) rather than in the multicellular mycelial form typical for all other attine ant gardens. Although they belong to the rimosus group, Cyphomyrmex wheeleri are known to cultivate mycelium gardens rather than yeast gardens. As I stated above, I was very surprized to find this ant at my home in Twin Oaks Valley, San Diego County, Calif.

Natasha J. M Ehdiabadi & Ted R. Schultz 2009. Natural History and Phylogeny of the Fungus-Farming Ants (Hymenoptera: Formicidae: Myrmicinae: Attini). Myrmecol. News 13: 37-55 (online 27 November 2009) ISSN 1994-4136 (print), ISSN 1997-3500 (online).

Another minute ant found in a Forelius mccooki midden. It resembled Strumigenys louisiana and was verified by Phil Ward at UC Davis. This is a tiny predator that feeds on springtails (insect order Collembola). The long, slender mandibles with teeth at apex are nicely adapted for quickly grasping springtails before they jump. This species has a large New World distribution: Arizona, midwest & gulf states south through Mexico, Central and South America. This species is truly a miniature version of the trap-jaw ant (Odontomachus)! It is certainly one of the most interesting ants I have ever found.

The above two images were taken about a year apart (August 2017 & July 2018) from a head found in a Forelius mccooki midden and an impoverished specimen found in a pitfall trap. Both were found in the bridle path in front of my home in Twin Oaks Valley, City of San Marcos, San Diego County, CA. The number of antennal segments appears to be 5, although they are not all clearly discernible in my image.

Using the AntWiki Key To US Strumigenys it appears close to S. rogeri or the S. rogeri complex; however, I have not verified this tentative ID.

The following is from The Ants by Bert Hölldobler and Edward O. Wilson (1990). When attacking collembolans, the mandibles of Strumigenys louisiana are extremely long and operate very much like a miniature spring trap similar to a trap-jaw ant: "Prior to the strike the mandibles are locked at nearly 180 degrees. This position is accomplished by special teeth at their bases that catch on the lateral lobes of the labrum. When the ants tense the retractor muscles alone the mandibles cannot move, but when the lateral lobes are also dropped the mandibles snap shut. The worker Strumigenys approaching a collembolan moves slowly and cautiously. She spreads her mandibles to the maximum angle and exposes two long hairs that arise from the paired lateral lobes. These hairs extend far forward of the ant's head and serve as tactile range finders for the mandibles. When they first touch the prey, its body is well within reach of the apical teeth. A sudden and impulsive snap of the mandibles literally impales it on the teeth, so that drops of hemolymph often well out of the punctures. If the collembolan is small relative to the Strumigenys, the ant lifts it into the air and then may sting it. All but the largest collembolans are quickly immobilized by this sequence of actions, and struggling is feeble and brief."

Left: Soil springtails compared with the "eye" of an ordinary sewing needle. They are actually colorless and about 1.0 to 1.5 mm long; however, backlighting makes them appear darker. With their springing device or furcula they can jump about 100 times their body length or about 7-8 inches (18-20 cm). Although they are abundant in some soils, they are barely visible with the naked eye. In just one handful of grassland soil there can be literally thousands of individuals representing hundreds of different species.

Left: Magnified view of a soil springtail taken with a Bausch & Lomb dissecting microscope and Sony W-300 camera. The springing device (furcula) is clearly visible on the ventral side of posterior end. A handful of soil can contain literally hundreds (or thousands) of springtails. Because of their small size and colorless bodies they are difficult to see with the naked eye. In order to acheive a more accurate rendition of its colorless body, I used backlighting and then "invert" with Adobe Photoshop.   Sony W-300 Camera Mounted   On Dissecting Microscope

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10. Myrmicinae: A 3rd Species Of Strumigenys (cf. S. membranifera)

Based on its 2-segmented club, I originally and incorrectly thought this was a minute species Solenopsis. After carefully examining its head on the advise of James Trager I can clearly see that it is Strumigenys. This is Strumigenys species #3 found in my Forelius mccooki midden at my home in Twin Oaks Valley! See following image:

To my surprise I found a third species of Strumigenys in my trusty Forelius mccooki midden! This species has shorter, triangular-shaped mandibles and is quite different from the previous two Strumigenys species. It resembles Antweb.com images of S. membranifera and may be that species. It has a remarkable world-wide distribution, including North & Central America, Europe, Africa, Madagascar, Mideast, Asia, Australia, and California. Some of these minute "micro-ants" that I have found in my yard may have been introduced with imported plants. They apparently have small colonies, and considering their very small size, they could easily be transported in potted plants.

Strumigenys photographed through Olympus compound microscope using the 4x and 10x objectives. This appear to be S. membranifera when compared with images by April Nobile on Antweb.com.

Head of Strumigenys taken through Bausch & Lomb dissecting microscope. This appear to be S. membranifera when compared with images by April Nobile on Antweb.com. This species is documented for California.

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11. Black Pyramid Ant (Dorymyrmex insanus) On External Link

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12. Argentine Ant (Linepithema humile) On External Link

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Smallest Ant In Twin Oaks Valley

13. Formicinae: Brachymyrmex patagonicus In Twin Oaks Valley

Rover Ant (cf. Brachymyrmex patagonicus) These ants have a dark brown-black body; they appear lighter in picture due to backlighting and alcohol solution. They were collected on flagstone in my backyard along with mite and springtail. There were also numerous Argentine ants in the area. On 19 September 2018 I collected one in a pitfall trap on bridle path in front of my house.

Feeding time at Wayne's Word: Three naturalized species representing 3 subfamilies of tropical ants sipping honey on a small section of flagstone in my backyard. This makes a grand total of 14 ant species living in my yard. It is amazing what you can find crawling around with a magnifying glass! See Ant Species In My Yard!.

Close-up view of a minute rover ant (Brachymyrmex patagonicus).

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Small Pheidole In Twin Oaks Valley

14. Myrmicinae: Pheidole (cf. P. californica) In Twin Oaks Valley

Major worker of Pheiodole californica.

Minute minor worker of big-headed ant (Pheidole) collected in pitfall trap on bridle path in front of my home in Twin Oaks Valley. The common name refers to major workers which I did not find (See left Ant.web image.) According to Phil Ward (UC Davis) it may be P. californica. It belongs to the Pilifera Group and is very close to P. clementensis. A larger species with long legs (P. vistana) is fairly common on the slopes of Owens Peak on the west side of Twin Oaks Valley. Pheidole is one of the largest ant genera with approximately 900 described species worldwide (and an estimated 1500 species)!

See Pheidole vistana On Owens Peak West Of Twin Oaks Valley    cf. Pheidole clementensis In Coastal Sage Near Palomar College

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22. Pheidole navigans Nest Of Minute Pheidole Species Among Roots & Decayed Stem Of An Aeonium Cultivar in Succulent Garden. Twin Oaks Valley, San Diego Co. 22 August 2021

This minute species is in the Pheidole flavens group (complex). The major and minor workers are smaller than the above P. californica collected in pitfall trap along bridle path. As stated above, this genus is called "Big-Headed Ants" because the major workers have larger heads in proportion to their bodies. I have only seen these minute workers and alate males below ground among the roots and decaying stem of an Aeonium arboreum cultivar. In fact, my wife Elaine was digging out her dying Aeonium when these ants were discovered. The surface and well-watered surrounding succulent garden was dominated by Argentine ants. My following observations suggest Pheidole navigans in the Flavens Group native to the neotropics: (1) Nests in rotting wood. (2) Flight (swarm) period July-August. (3) Predominant longitudinal rugae: Rugae extend from mandibles & clypeus to posterior of head (above and below eyes). (4) Distributed in the nursery trade--This certainly applies to some of the ant species I have found in pitfall traps placed along bridle path near my home in Twin Oaks Valley. There are many nurseries in this area very close to my residence. Some ants are readily transported in potted plants and even in the corrugations of boxes. Delivery trucks arrive daily at these large nurseries. According to Phil Ward, Univ. of California, Davis (Personal Communication 7 Sept. 2021), this species is indeed Pheidole navigans: "This species has been confused with (and misreported as) "P. moerens" in some of the literature." Pheidole navigans was originally described in Germany, intercepted during quarantine inspection of orchids originating from Veracruz, Mexico.

Pheidole megacephala In Corrugations At Farmer's Market On Maui!   Pheidole navigans by Joe A. McGown, Mississippi State University

Some Of The Following Images Were Originally Identified As Pheidole sp.
However, They Are All Conclusively Identified As Pheidole navigans

In this image I have pushed my old Nikon D-90 SLR to its limits. For additional images with more detail, please refer to the above link by Joe A. McGown. Compare the head length of major worker (0.85 mm) with 3 average grains of ordinary table salt stacked together (1.0 mm)!

Modest Photographic Equipment Used On Pheidole navigans

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Another Minute Subterranean Ant In Pitfall Trap

15. Ponerinae: Hypoponera opacior In Twin Oaks Valley

Hypoponera opacior, H. opaciceps & H. inexorata reported from CA by Phil Ward.

Using the AntWiki Key To US Hypoponera it is H. opacior; ID verified by Phil Ward on 24 July 2018.

The subfamily Ponerinae includes some very interesting species, including the sickle-jaw ant (Leptogenys falcigera) in Maui, trap-jaw ant (Odontomachus bauri) in Costa Rica, and Panther Ant (Pachycondyla) from Machu Picchu in the Peruvian Andes.

See Other Genera In Subfamily Ponerinae On Wayne's Word

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Queen Ant (Dorymyrmex insanus)

I originally thought this was Tapinoma sessile; however, on 2nd thought, this is probably Dorymyrmex insanus since nests of this species have been observed in this bridle path. Latter ID verified by myrmecologist James Trager (3 Sept. 2021): "Queen is indeed Dorymyrmex, easily recognized by her long maxillary palps, and by the fact that her gastral cross-section is higher than it is wide."

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Small Male Alate (Species Undetermined)

This small alate male (winged male) is probably from nearby swarm of small ants with single petiole node. Several ant species in Twin Oaks Valley are in the subfamily Dolichoderinae (one petiole; no acidopore) and subfamily Formicinae (one petiole; with acidopore). As of May 2024, I determined this is a male Argentine ant (Linepithema humile).

Similar Winged Male On Owens Peak Dorymyrmex bicolor Male Owens Peak Swarms Of Winged Males On Owens Peak   (Species With 2 Petiole Nodes & One Petiole Node)

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15b. Minute Wasps: Including Parasitoid Species

The Estimated Number Of Minute Parasitoid Wasp Species May   Exceed The Total Number Of Described Beetles On Our Planet!

Parasitoid Wasp In Midden Of Forelius mccooki Nest

Minute Parasitoid Wasp: Family Diapriidae (Superfamily Diaprioidea). It was identified in the genus Trichopria on iNaturalist (May 2024). This minute wasp was found in the midden of a Forelius mccooki colony on bridle path in front of my home. Parasitoid wasps include some of the smallest insects with the greatest number of species. I always thought beetles had the largest number with 300,000 described species. The parasitoid wasp superfamily Chalcidoidea alone has an estimated 500,000 species! Wasps in family Diapriidae have been found associated with ant nests in Argentina according to Psyche: A Journal of Entomology, including the Argentine ant (Linepithema humile). The Diapriidae are a family of parasitoid wasps in the superfamily Diaprioidea. These tiny insects have an average length of 2–4 mm. Diapriids show considerable diversity of form, with aptery (lack of wings) fairly common. They typically attack larvae and pupae of a wide range of insects, especially flies & ants. They are known to attack fungus-farming ants of the genus Cyphomyrmex. Surprisingly enough, I have found this ant at Wayne’s Word in Twin Oaks Valley. About 2,300 species have been described in 200 genera. They are divided into three subfamilies, and the group has a global distribution.   See Fungus Farming Ant (Cyphomyrmex wheeleri)    Some Additional Images of Fungus Farming Ant

Two additional wasp species in Forelius mccooki midden. Left: A chalcid wasp in the family Chalcididae. Note the enlarged leg segments (femora). Right: Fig wasp Pleistodontes imperialis (family Agaonidae), symbiotic pollinator of rustyleaf fig (Ficus rubiginosa) that grows across the street from bridle path. The chalcid wasp may be a parasitoid species. I found a dozen individuals in the midden sample so they may be parasitic on this Forelius mccooki colony.

Fig Wasps (Family Agaonidae) Also in Superfamily Chalcidoidea

A. Close-up view of a male and female fig wasp (Pleistodontes imperialis) that inhabits the syconia of the Australian rustyleaf fig (Ficus rubiginosa). The slender ovipositor on female wasp is too short to penetrate the ovary of long-style flowers; therefore she does not lay eggs in these flowers. The smaller, wingless male has large mandibles and a greatly reduced body which has two primary purposes: (1) Inseminating the female and (2) Chewing exit tunnels through the syconium wall through which the females escape. The "eye" of an ordinary sewing needle is shown for a size comparison. These wasps were collected from trees growing by the old Life Science building. The biology students were always amazed when I brought them into my laboratory classes. B. A non-pollinator "bogus" fig wasp collected from the syconium of the Baja California wild fig (Ficus palmeri, or possibly Ficus brandegeei). [Note: latest research treats the two previous fig binomials as synonyms of F. petiolaris.] The ovipositor is much longer than the symbiotic pollinator wasp. In fact, some non-pollinator wasps can penetrate the entire syconium wall from the outside. They can also lay eggs in long-style fig flowers reserved for fig seeds. Consequently, no seeds are produced in these flowers. In addition, these "bogus" fig wasps do not pollinate fig flowers. Although they do not benefit the fig tree, non-pollinator wasps of the families Torymidae and Eurytomidae are common inhabitants of New World monoecious fig syconia. Their coexistence with natural fig pollinator wasps is a complex and perplexing coevolutionary problem in fig biology.

Pollination Of The Rustyleaf Fig By Its Symbiotic Fig Wasp Pleistodontes imperialis      See Heads Of Snakefly (Raphidioptera--Raphidiidae) Found In Pitfall Trap On Bridle Path

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It never ceases to amaze me what I find in my insect pitfall traps set in Twin Oaks Valley. The type location for this tiny wingless wasp is the Congo region of Africa! I escape from all the trials and tribulations of southern California in my world of insects! Of course, iNaturalist is a marvelous website for identifying difficult & little known species.

See Matching Images For This Wasp On WaspWeb.org

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Square Headed Wasps (Family Crabronidae)

My latest tiny wasp visitor. This is where I find a lot of my interesting insects at my home. I have pitfall traps set throughout this area.

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Other Ant Species Found Along the Lower Slopes of Merriam
Mountains and Owens Peak That Border Twin Oaks Valley

16. Formicinae: Myrmecocystus In Merriam Mtns

Honey Pot Ant (Probably Myrmecocystus wheeleri)

More Images Of Myrmecocystus In The Merriam Mtns   Myrmecocystus mexicanus near Holbrook, Arizona

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Owens Peak West Of Twin Oaks Valley

17. Formicinae: Myrmecocystus testaceus

I recently found another ant species in my traps on Owens Peak. I am reasonably certain it is a large-eyed, nocturnal species of honeypot ant (Myrmecocystus testaceus). It clearly belongs to the subfamily Formicidae with one petiole node and an acidopore. In addition, it has long maxillary palps typical of Myrmecocystus. I also collected this species in a trap at Daley Ranch. This makes a grand total of 16 species for Owens Peak!

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Ant Species 18 - 21 On External Links

18. Red Harvester Ant (Pogonomyrmex subnitidus) On External Link 19. Black Harvester Ant (Veromessor andrei) On External Link       Note: Also Listed As Messor andrei In Some References 20. Big-Headed Ant (Pheidole vistana) On External Link 21. Little Black Ant (Monomorium minimum) On External Link I originally thought species #21 on the dead preying mantis was Cardiocondyla mauritanica until I brought it home and carefully examined it under the dissecting microscope. In fact, I brought the entire dead mantis home because it was covered by numerous ants, including a few red & black fire ants (Solenopsis xyloni). The most obvious difference was no propodeal spines that are clearly present on Cardiocondyla. In addition, the postpetiole is not enlarged as in Cardiocondyla and there were erect hairs on the dorsum of head & thorax. Send E-Mail Message To Wayne's Word:

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Some On-Line Ant Resources

Ant Genera Photographed By Alex Wild Ants Of The Southwest By Dale Ward Ants Of California By Phil Ward, UC Davis       Images Of Ant Subfamilies In Bug Guide Antweb: Images Of All Ant Subfamilies Antwiki: Keys & Descriptions Of Ants

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