Camponotus modoc

Nests in rotten logs and stumps, or rarely under stones. They may also nest in the wood of buildings, especially log cabins in forested areas.

Compare with Camponotus herculeanus, Camponotus laevigatus, Camponotus pennsylvanicus, Camponotus schaefferi, Camponotus texanus.

The majors, minors and females of C. modoc are predominantly black, dull ants. The scapes are without erect and suberect setae (except at apex), the setae on the clypeus are located mostly along the borders, the dorsal and ventral surfaces of the head have few erect and suberect setae, the cheeks and sides of the head are without erect and suberect setae. Most surfaces have golden, appressed setae, which are scarce on the head and mesosoma and slightly more abundant on the gaster, where at least a few of the appressed setae overlap adjacent setae, but most are less than half (> than 0.15 mm) the length of the erect and suberect setae. The appressed setae on the gaster are mostly short and may be even absent in some specimens.

The males are moderately large (10 mm total length), black ants.

Comparisons
Camponotus modoc has been considered to be a subspecies of either Camponotus herculeanus or Camponotus pennsylvanicus. Brown (1950) supported Creighton’s (1950) recognition of C. modoc as separate from C. pennsylvanicus (S Canada, US) but considered it to be more similar to C. herculeanus (S Canada, US). It has been shown to be genetically similar to C. pennsylvanicus (Sämi Schär, et al., 2018). It can usually be separated from both of these species as the appressed setae on the gaster are much shorter (< 0.15 mm) than the erect and suberect setae (about equal in length in the other 2 species, or > 0.15 mm). The appressed setae on the mesosoma of C. modoc are sparse and do not overlap adjacent setae, whereas the appressed setae on the mesosoma of the other 2 species are abundant and even extend to the lateral surface of the propodeum and many setae overlap adjacent setae. There is considerable geographic variation of the length of the setae (see Camponotus pennsylvanicus for further discussion). The scapes of the majors of C. modoc extend nearly 1 funicular segment past the posterior lateral corner, which separates it from C. herculeanus in which the scape of the largest majors barely surpasses the posterolateral corner of the head. Camponotus herculeanus can also be separated from C. modoc by the color (C. modoc usually has red legs and at least part of the mesosoma is usually reddish). There is a considerable amount of variability in all characters and these 2 taxa can be nearly indistinguishable.

The clypeus of C. modoc has weakly developed angles along the anterior border, similar to those of Camponotus schaefferi (Arizona, New Mexico) and Camponotus texanus (W Texas). Camponotus modoc can be easily separated from these two species as the side of the mesosoma is dull and punctated, not nearly smooth and glossy as in the latter two species.

Specimens of C. modoc from Mexico have very short appressed setae on the gaster. Specimens that completely lack appressed setae on the dorsum of the gaster are possibly Camponotus laevigatus.

Camponotus modoc is found near sea level in Washington and British Columbia, but is subalpine further south (Wheeler, 1917c). It is found in forests (Cole, 1942), and in a variety of habitats, ranging from grassland, birch and chokecherry thickets, in juniper, pinyon pine and sagebrush hills, hedges, deciduous forests, cottonwood, oak, beach, pine, fir, spruce and aspen forests, wet grassy meadows, hardwood forests, riparian forests, subalpine fir and spruce forests, burned sagebrush and burned lodgepole pine forests. It is also found in ponderosa pine, pine-spruce popular up to subalpine forests (Mackay and Mackay, 2002). Palladini et al. (2007) found it most prevalent in older stands of temperate coniferous forests.

Distribution based on Regional Taxon Lists
Nearctic Region: Canada, United States. Neotropical Region: Mexico.

Camponotus modoc nests in wood (Mackay and Mackay, 2002), specifically under the bark and in logs, stumps and standing dead trees, especially conifers. The wood is often rotten, with loose bark. They rarely nest in the soil, sometimes in soil at the base of stump, rarely under stones (Mackay and Mackay, 2002), wood or pieces of bark. Gregg (1963) concludes they more commonly nest under stones than in logs in Colorado. We have also found that they often nest under large stones, especially in the northern part of range (Montana, Canada). One colony may have been in a large soil mound (Gregg, 1963).

They occur in soils ranging from clay loam, dark brown loam, rocky clay, rocky loam, sandy soil to rocky sand.

Colonies are huge (Wheeler, 1917c) and contain multiple nest queens. Workers generally escape when the nest is opened, but workers in large nests can be aggressive.

Sexuals and brood are found in nests from March (Mexico) - October (USA), suggesting that sexuals overwinter in the nest. A flight occurred in June at 19:00. Dealate females were collected in June - October, often under stones or under loose bark of logs and stumps.

Foragers are primarily nocturnal (VabLaerhoven et al., 2003; Hansen and Klotz, 2005), but are also diurnal predators (Bibionidae) from 10:00 - 18:30 and are often collected in pitfall traps. Camponotus modoc tends aphids (Jones, 1929). They collect aphid honeydew and Valeriana edulis floral nectar (Petry et al., 2013). Foragers remove petals from Rhododendron macrophyllum and collect nectar from the base of the flower (Weiser, 2002). They prey on the western spruce budworm pest, Choristoneura occidentalis (Lepidoptera: Tortricidae) (Youngs and Campbell, 1984). They are able to forage at lower temperatures than many other species of ants (Palladini et al., 2007).

Myrmecophilus sp. crickets were found in nests (Chihuahua, Mexico). Reemer (2012) discusses the parasitism by the syrphid fly parasite Microdon sp. It is the principal host of the Microdon piperi, which is also found with other species of Camponotus (Akre et al., 1988). The larvae mimic and feed on the ant brood, and their life cycle is synchronized with the brood cycle of the host (Akre et al., 1988).

They have been impacted by the recent invasion of Myrmica rubra into British Columbia but are able to attack columns of the Myrmica workers (Naumann and Higgins, 2015).

Hansen et al (1999) describe the infrabuccal chamber and survey the contained bacteria.

The use of artificial nests showed that colony founding queen survivorship of Camponotus vicinus was less sensitive to moisture levels than were C. modoc queens (Mankowslki and Morrell, 2011).

Camponotus modoc is a principal structural pest in western United States, excavating nests in structural timber, fiberglass, foam insulation, and make distracting noise in the walls of houses (Hansen and Klotz, 2005).

The specimen from Phoenix, AZ was in an apitong (Dipterocarpus) board from the Philippines.

Additional Notes
Mackay and Mackay (2002), in New Mexico: Found in forested areas, ranging from deciduous through pinyon pine and ponderosa pine, pine-spruce-popular and spruce forests up to subalpine fir (2490 - 3000 meters altitude). Brood and reproductives occurred in nests from June to September, dealate females were found from July to October. Workers escape with brood when the nest is disturbed, and are preyed on by members of the Formica rufa species complex. One colony was nesting together with Formica argentea, another with Formica hewitti, a third with Formica neoclara. Another colony was together with Tapinoma sessile.

Nevada, Wheeler and Wheeler (1986) - C. modoc is strictly a montane ant: 59 records were from the Coniferous Forest Biome, 7 were from the ecotone above, and 3 were from the Alpine. We have nest data for only 18 colonies: all were nesting in rotten wood. Medias and minors were found tending aphids on small pine branches. Steller's jays (Cyanocitta stelleri) and robins (Turdus migratorius) fed on sexual forms during a mating flight on 18 July in the Coniferous Forest Biome. The myrmecophile Xenodusa reflexa (Walker) (Coleoptera: Staphylinidae; del. L.M. Chilson) was taken in a nest.

Castes

 * Worker

Nomenclature

 *  modoc. Camponotus (Camponotus) herculeanus var. modoc Wheeler, W.M. 1910d: 333 (s.w.q.m.) U.S.A. Combination in C. (Camponotus): Emery, 1925b: 72. Subspecies of pennsylvanicus: Creighton, 1950a: 369; of herculeanus: Brown, 1950d: 158. Raised to species: Hunt & Snelling, R.R. 1975: 22; Smith, D.R. 1979: 1426; Mackay, Lowrie, et al. 1988: 104 (in key).

Type Material
Numerous specimens collected from a variety of US states. Despite the range of locations Wheeler stated California is the type locality. Not found by Mackay (2019).

Description
Major worker measurements (mm): HL 2.22 - 3.18, HW 2.06 - 3.70, SL 2.14 - 2.70, EL 0.51 - 0.70, CL 0.66 - 1.11, CW 0.90 - 1.29, WL 2.98 - 4.02, FFL 1.84 - 2.50, FFW 0.58 - 0.79. Indices: CI 93 - 116, SI 81 - 96, CLI 116 - 143, FFI 26 - 32.

Mandible with 5 teeth; anterior border of clypeus straight or concave with distinct depressed anteclypeus, lateral angles poorly developed; head strongly narrowed anteriorly, greatly widened posteriorly, posterior margin slightly concave; eyes small, failing to reach sides of head by ½ to more than 1 maximum diameter; scape extending past posterior lateral corner of head by nearly 1 - 2 funicular segments; mesosoma massive, metanotum well defined; dorsopropodeum slightly shorter than posteropropodeum, with slight angle between two faces, propodeal spiracle elongate; petiole narrow in profile, apex weakly convex as seen from front.

Erect and suberect setae present on clypeus, mostly along borders, present along frontal carinae, extending to posterior margin, absent on cheeks, side of head, scapes (except at apex), few setae on ventral surface of head, few setae scattered on dorsum of mesosoma, moderately abundant on gaster, absent on tibiae, except for double row of bristles on flexor surface (some specimens have suberect setae on all of surface); appressed pubescence sparse, scattered on head (0.08 mm), dorsum of mesosoma and dorsum of gaster, often short (0.02 - 0.15 mm, ¼ - ½ length of erect and suberect setae), setae not overlapping adjacent setae on most surfaces, except for gaster, where some setae touch adjacent setae.

Head densely and evenly punctate, with larger, scattered punctures on sides of head, mesosoma densely and evenly punctate, gaster finely transversely striolate, surfaces dull, except for side of head, which is weakly shining.

Black, cheeks dark reddish brown, legs red, parts of mesosoma and petiole may be red.

Minor worker measurements (mm): HL 1.70 - 2.36, HW 1.50 - 2.18, SL 1.78 - 2.46, EL 0.43- 0.58, CL 0.51- 0.75, CW 0.80 - 1.05, WL 2.44 - 3.30, FFL 1.50 - 2.08, FFW 0.46 - 0.66. Indices: CI 88 - 96, SI 95 - 113, CLI 140 - 156, FFI 30 - 33.

Similar to major, except sides of head nearly parallel, narrowed anteriorly with rounded sides; scape extends about ½ length past posterior lateral corner of head, eyes nearly reach sides of head, posterior margin weakly convex to concave.

Pilosity, sculpture and color as in major worker.

Female measurements (mm): HL 2.92 - 3.16, HW 3.12- 3.44, SL 2.46 - 2.76, EL 0.71 - 0.89, CL 0.91 - 1.11, CW 1.28 - 1.40, WL 5.12 - 5.56, FFL 2.40 - 2.76, FFW 0.75 - 0.84. Indices: CI 107 - 109, SI 84 - 87, CLI 121 - 140, FFI 30 - 31.

Mandible with 5 teeth; clypeus as in major worker; sides of head straight, converging anteriorly, posterior margin convex to slightly concave; eyes failing to reach sides of head by about ¼ - ½ minimum diameter; ocelli well developed; scape extending slightly more than 1 funicular segment past posterior lateral corner of head; propodeum rounded with dorsopropodeum shorter than posteropropodeum; petiole narrow in profile, apex relatively sharp.

Erect and suberect setae, and appressed pubescence as in major, except appressed setae on gaster tiny (0.03 mm); sculpture and color as in major.

Male measurements (mm): HL 1.45 - 1.47, HW 1.34 - 1.36, SL 1.68 - 1.74, EL 0.50 - 0.51, CL 0.38 - 0.41, CW 0.64 - 0.66, WL 3.04 - 3.36, FFL 2.08 - 2.08, FFW 0.45 - 0.47. Indices: CI 92 - 93, SI 115 - 119, CLI 158 - 173, FFI 22.

Small, dark specimen, not differing noticeably from those of other species.

References based on Global Ant Biodiversity Informatics

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