Subfamily FORMICINAE Author: Joe A. MacGown and Nicole Rasoamanana |
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 Camponotus chromaiodes, full face view of major worker (MS, Prentiss Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, lateral view of major worker (MS, Prentiss Co.) (Photo by Joe A. MacGown) |
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 Camponotus chromaiodes, full face view of minor worker (MS, George Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, lateral view of minor worker (MS, George Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, dorsal view of minor worker (MS, George Co.) (Photo by Joe A. MacGown). |
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 Camponotus chromaiodes, dorsal view of a minor worker (red form) (MS, Pontotoc Co.) (Photo by Joe A. MacGown). |
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 Camponotus chromaiodes, full face view of a queen (TN, Franklin Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, lateral view of an alate queen (TN, FranklinCo.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, dorsal view of an alate queen (TN, Franklin Co.) (Photo by Joe A. MacGown). |
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 Camponotus chromaiodes, full face view of a male. (MS, Panola Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, full face view of a male. (MS, DeSoto Co.) (Photo by Joe A. MacGown). |
 Camponotus chromaiodes, full face view of a male. (MS, DeSoto Co.) (Photo by Joe A. MacGown). |
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 Camponotus chromaiodes, dorsal view of gaster. Note the pubescence extending well past the edges of the tergites; more than half of the length of those hairs reach the next tergite (Compare to C. pennsylvanicus gaster). |
 Camponotus chromaiodes workers under bark of a dead Pinus taeda log with Microdon sp. larvae (Syrphidae) [larvae in lower left corner].. |
 Microdon sp. larvae found with C. chromaiodes in colony under bark of pine log. |
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Introduction
Ants in the genus Camponotus are collectively known as carpenter ants because some species nest in wood, including man-made structures. This genus includes some of the largest and most common ants in the world, and they are found in all biogeographical regions (Bolton, 1995a). More than 900 species of Camponotus are known worldwide, with 50 species reported from the United States (Hansen and Klotz, 2005), and 20 species found east of the Mississippi River (Deyrup, 2003; Smith, 1979).
Species in this genus are variable in size with workers ranging in size from 3 to 15 mm or more in length and queens (also referred to as females) of some species attaining a length of 19 mm or more. Many species are polymorphic. Workers have a 12-segmented antenna that lacks an apical club. Antennal fossae do not touch the posterior border of the clypeus. Ocelli are not present on the heads of workers. The workers of most species have an indistinct metanotal suture between the promesonotum and the propodeum, although this suture is present in C. sexguttatus and some members of the subgenus Colobopsis. Those species that lack the obvious and deep metanotal suture have the shape of the alitrunk in a smoothly curved arc (as seen in profile).
Camponotus chromaiodes is in the subgenus Camponotus, which includes some of the true carpenter ants that nest in wood. Species in this subgenus are large ants with workers ranging approximately 6–14 mm in length. The clypeus is ecarinate to only scarcely carinate, antennal scapes are not flattened at the bases, clypeal fossae are well developed, and the heads of major workers are usually broader than long. This subgenus includes three species in Mississippi (MacGown et al., 2007).
Camponotus chromaiodes is sometimes called the red carpenter ant because of the reddish coloration often present on the posterior part of the mesosoma, petiole, base of the gaster, and legs. Major workers are large, about 6–14 mm in overall length, with the remainder of the body usually black, although color is variable. The gaster bears long, golden appressed pubescence that overlaps the posterior margins of the gastral tergites by at least half its length. Dark forms may be difficult to separate from C. pennsylvanicus without careful examination of the gastral pubescence (Mackay, 2019).
Taxonomic History
Taxonomic history follows Bolton (2025).
Camponotus chromaiodes Bolton, 1995 valid
- Camponotus chromaiodes Bolton, 1995b: 130. Replacement name for Camponotus ferrugineus Fabricius, 1798. [Junior primary homonym of Formica ferruginea Christ, 1791.] [For earlier history of this taxon see under Camponotus ferrugineus Fabricius, 1798.]
- Combination in Camponotus (Camponotus): Bolton, 1995b: 130.
- Status as species: Coovert, 2005: 165; Hansen & Klotz, 2005: 82; MacGown & Forster, 2005: 65; MacGown et al., 2007: 10; Ellison et al., 2012: 120; Mackay, 2019: 199 (redescription).
Common Name
Red carpenter ant; ferruginous carpenter ant; rust-colored carpenter ant (Smith, 1965)
Diagnosis
Workers of Camponotus chromaiodes are large, dark carpenter ants with variable reddish coloration. The head and gaster are usually black, while the mesosoma and legs are often partly deep red to ferruginous. In many workers, the base of the first gastral tergite is reddish, and the posterior margins of the gastral tergites are reddish brown. Color is variable, however, and some individuals may have the mesosoma almost entirely reddish, whereas others are much darker and may appear nearly black.
The gaster is covered with dense, long, golden appressed pubescence, giving it a distinct golden sheen. In dorsal view, these appressed hairs overlap the posterior margins of the gastral tergites by at least half their length and may nearly obscure the surface of the integument (Mackay, 2019). This dense golden gastral pubescence is one of the most useful characters for recognizing the species, especially in darker workers that resemble Camponotus pennsylvanicus. The mesosoma, including the sides of the propodeum, also bears scattered golden appressed pubescence. Erect and suberect setae are present on the gaster, and some of the appressed hairs are nearly as long as the erect setae. Antennal scapes extend approximately 2–3 funicular segments beyond the posterolateral corners of the head.
Dark forms of C. chromaiodes are difficult to separate from C. pennsylvanicus on color alone. The most reliable distinguishing features are the dense, long, golden appressed pubescence on the gaster, the overlap of these hairs across the posterior margins of the gastral tergites, and the frequent reddish coloration at the base of the first gastral tergite (Mackay, 2019).
Identification
Descriptions for each caste are based on examination of MEM specimens.
Minor worker. TL: 5.78–7.13 mm; HL: 1.61–1.81 mm; HW: 1.30–1.52 mm; SL: 1.95–2.30 mm; ML: 2.35–2.86 mm; EL: 0.35–0.44 mm (n=7, MEM specimens).
Head in full-face view longer than broad, subrectangular to weakly elongate; lateral margins distinctly convex, narrowing anteriorly toward the mandibular insertions; occipital margin broadly convex to nearly straight. Eyes moderately large, weakly convex, situated slightly anterior to midlength of head, not breaking lateral cephalic margin. Frontal carinae short, posteriorly subparallel. Clypeus ecarinate to weakly carinate; anterior margin straight to weakly convex, not strongly projecting. Mandibles triangular; masticatory margin with five teeth. Antennal scape long and slender, not basally flattened, surpassing occipital margin by more than three funicular segments when laid back; scapes lacking conspicuous erect setae.
Mesosoma moderately robust; dorsal outline evenly and continuously arched in profile. Pronotum and mesonotum forming a smooth convex outline; metanotal groove weakly impressed. Propodeum with dorsal and declivitous faces subequal in length, their junction broadly rounded. Petiole nodiform to weakly scale-like; node higher than long, with rounded apex in anterior view. Gaster oval.
Pilosity sparse to moderate on head and mesosoma. Clypeus with several erect setae along anterior margin and usually a pair near posterior margin; frontal area and vertex with a few erect to suberect setae. Genae, lateral margins of head, and posterolateral corners lacking conspicuous erect setae. Mesosoma, petiole, and gaster with scattered erect to suberect setae. Tibial pilosity mostly appressed to decumbent, with short bristle-like setae along the distal portion of the posterior tibiae. Appressed pubescence sparse on head and mesosoma, scattered on sides of propodeum and petiole, but dense, long, and golden on the gaster, often obscuring the underlying sculpture and giving the gaster a bronzy or golden sheen.
Sculpture fine but distinct. Head densely and finely punctate to punctulate, opaque to weakly shining. Mandibles finely striate-punctate basally, with teeth smooth and shining. Dorsum of mesosoma finely coriaceous to punctulate; sides of mesosoma coriaceous, becoming more distinctly punctate on parts of the mesopleuron and propodeum. Petiole finely punctate to coriaceous. Gaster finely punctate to weakly coriaceous, but surface largely obscured by dense golden pubescence.
Coloration distinctly bicolored but variable. Head and gaster black to dark brown; mesosoma predominantly red to ferruginous, sometimes darkened in part; petiole red to reddish brown. Anterior margin of the first gastral tergite often reddish. Antennae dark brown to black, with funicular segments sometimes lighter apically. Legs reddish brown to ferruginous, with tibiae and tarsi usually darker.
Major worker. TL: 8.90–13.85 mm; HL: 2.55–3.66 mm; HW: 2.50–4.22 mm; SL: 2.32–3.04 mm; ML: 3.45–5.31 mm; EL: 0.52–0.72 mm (n=7, MEM specimens).
As in the minor worker, but larger and more robust, and differing as follows. Head broader and more subquadrate, nearly as broad as long to slightly longer than broad; lateral margins weakly convex; occipital margin nearly straight to weakly concave medially; posterolateral corners broadly rounded. Eyes situated near or slightly posterior to head midlength. Frontal carinae lyrate, diverging anteriorly and posteriorly. Clypeus ecarinate or with median carina obsolete; anterior margin with shallow lateral concavities delimiting a short, truncate median lobe. Scapes surpassing occipital margin by approximately two funicular segments. Mesosoma more robust but otherwise as in the minor worker; propodeum, petiole, and gaster as in the minor worker.
Pilosity as in the minor worker but more abundant, especially on head and mesosoma: frontal area and vertex with two irregular longitudinal rows of suberect setae; genae with numerous erect setae; pronotal dorsum with about 9–13 pairs of erect setae, mesonotal dorsum with about 4–8 pairs, propodeal dorsum and posterodorsal angles with several. Sculpture as in the minor worker but generally stronger; mandibles opaque, coarsely striate-punctate basally, teeth smooth and shining.
Coloration as in the minor worker, though major workers may be darker. Dark forms can resemble Camponotus pennsylvanicus, but the dense, long, golden appressed pubescence on the gaster is characteristic of C. chromaiodes.
Queen. TL: 15.00–15.89 mm; HL: 3.14–3.34 mm; HW: 3.61–3.86 mm; SL: 2.78 mm; ML: 5.15–6.21 mm; EL: 0.7– 0.82 mm (n=5, MEM specimens).
As in the major worker, but larger, with the head proportionally broader and the mesosoma fully developed for flight. Head subrectangular; lateral margins nearly straight to weakly convex, weakly converging behind the eyes; occipital margin nearly straight. Eyes large, positioned posterior to head midlength; ocelli well developed. Clypeus simpler than in the major worker, weakly carinate to ecarinate, with anterior margin straight to weakly convex and not strongly projecting (as in the minor worker); mandibles triangular with five teeth. Antennae 12-segmented; scape moderately long, surpassing occipital margin by one to two funicular segments. Mesosoma robust: pronotum short in dorsal view; mesoscutum well developed and convex; mesoscutellum distinct and elevated; propodeum short and rounded, dorsal face shorter than declivity. Petiole narrow in profile, higher than long; node apex flat to weakly concave in anterior view (rounded in the major worker). Wings, when present, lightly infuscate, with brownish venation. Sculpture, pilosity, and coloration otherwise as in the major worker, the gaster with dense golden appressed pubescence.
Male. TL: 9.02–10.81 mm; HL: 1.60–1.85 mm; HW: 1.41–1.86 mm; SL: 1.70–2.14 mm; ML: 3.72–4.46 mm; EL: 0.58–0.66 mm (n=5, MEM specimens).
Head longer than broad in full-face view, narrowed anteriorly, with posterior margin broadly convex. Eyes very large and strongly convex, distinctly interrupting the lateral cephalic outline. Ocelli well developed and prominent. Frontal carinae short, weakly developed. Clypeus not produced; anterior margin straight to weakly convex. Mandibles reduced, triangular, with a single acute apical tooth. Antennae 13-segmented; scape elongate, surpassing the posterior margin of the head when laid back.
Mesosoma robust and fully developed for flight. Pronotum short and nearly vertical; mesoscutum large, strongly developed, rising steeply anteriorly and rounding onto the dorsal disc; mesoscutellum convex and elevated. Propodeum short and rounded, with dorsal face shorter than declivity. Petiole low and nodiform, with rounded apex in profile. Gaster elongate-oval.
Sculpture finely and densely imbricate to punctulate throughout, giving the body a matte to weakly shining appearance. Head and mesosoma finely sculptured; gaster finely sculptured but partly obscured by appressed pubescence.
Pilosity sparse to moderate. Head and mesosoma with scattered fine, suberect setae; petiole with a few standing setae near the node apex; gaster with scattered fine setae and appressed golden pubescence, the latter more conspicuous along the posterior margins of the gastral tergites.
Coloration predominantly dark. Head, mesosoma, petiole, and gaster black to dark brown; mandibles, antennae, and legs dark brown to reddish brown, with some lighter brown areas on the funiculus and tarsi. Gaster with golden to bronzy appressed pubescence, especially visible as transverse bands near the posterior margins of the tergites. Wings lightly infuscate to subhyaline, with amber to brown venation and a distinct pterostigma.
Biology and Economic Importance
Camponotus chromaiodes is one of the most common carpenter ants in Mississippi (MacGown & Brown, 2006; MacGown et al., 2007) and may form large colonies containing many thousands of workers (Hansen & Klotz, 2005). Based on MEM observations, nests are often found in and beneath rotting logs and stumps, with galleries typically extending into the soil. Colonies also occur in standing dead trees and in moist, rotten, or otherwise degraded wood in buildings, where the species may be of minor structural concern, especially when wood has already been softened by moisture or decay.
Workers forage mostly at night and feed on small insects, honeydew, fruit juices, and plant sap (Smith, 1965; Mackay, 2019). Alates have been collected throughout the summer and into early fall in Alabama and Mississippi; sexuals may overwinter in the parental nest before dispersing the following year (Smith, 1965).
This species supports a variety of associated organisms. The ant-loving cricket Myrmecophilus pergandei and larvae of Microdon sp. (Diptera: Syrphidae) have both been collected in C. chromaiodes colonies in this region. The species is also known to harbor bacte
Pest status
Camponotus chromaiodes nests in rotting logs, stumps, standing dead trees, and other moist or decayed wood, and may occasionally become a structural pest when colonies occur in buildings, although it is not usually considered a major house pest (Smith, 1965; Forester, 2003; Hansen & Klotz, 2005). Like other carpenter ants, it does not feed on wood, but excavates galleries for nesting, usually in wood already damaged by moisture or decay. Workers do not sting, but they can bite and may cause minor irritation by ejecting formic acid from the acidopore at the tip of the gaster.
Distribution
Camponotus chromaiodes is broadly distributed in eastern North America, occurring from the northeastern United States west to the Midwest and south through the southeastern states, including Mississippi and Alabama (Smith, 1979; MacGown & Forster, 2005; Mackay, 2019). Published records include much of the eastern United States and southern Canada. The species is well established in Mississippi and neighboring states.
Its occurrence in Florida remains uncertain. Mackay (2019) listed a Florida record based on a single dealate queen from Madison County, but the species was not included in Deyrup’s (2003) updated list of Florida ants. Additional Florida records are needed to confirm its presence there.
Literature Cited
Bolton, B. 1995a. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp.
Bolton, B. 1995b. A taxonomic and zoogeographical census of the extant ant taxa (Hymenoptera: Formicidae). Journal of Natural History 29:1037–1056.
Bolton, B. 2025. An online catalog of the ants of the world. Available from https://antcat.org. (accessed 3 June 2026).
Coovert, G. A. 2005. The ants of Ohio. Bulletin of the Ohio Biological Survey (New Series) 15(2):1–196.\ Deyrup, M. 2003. An updated list of Florida ants (Hymenoptera: Formicidae). Florida Entomologist 86:43–48.
Ellison, A. M.; Gotelli, N. J.; Farnsworth, E. J.; Alpert, G. D. 2012. A field guide to the ants of New England. New Haven: Yale University Press, xv + 398 pp.
Forester, J. A. 2003. The Ants (Hymenoptera: Formicidae) of Alabama. Master’s Thesis, Auburn University, Auburn, Alabama.
Hansen, L. D.; Klotz, J. H. 2005. Carpenter ants of the United States and Canada. Ithaca, New York: Cornell University Press, xiii + 204 pp.
MacGown, J. A.; Brown, R. L. 2006. Survey of ants (Hymenoptera: Formicidae) of the Tombigbee National Forest in Mississippi. Journal of the Kansas Entomological Society 79:325–340.
MacGown, J. A.; Brown, R. L.; Hill, J. G.; Layton, B. 2007. Carpenter ants of Mississippi. Mississippi Agricultural and Forestry Experiment Station Bulletin 1158:1–35.
MacGown, J. A.; Forster, J. A. 2005. A preliminary list of the ants (Hymenoptera: Formicidae) of Alabama, U.S.A. Entomological News 116:61–74.
Mackay, W. P. 2019. New World carpenter ants of the hyperdiverse genus Camponotus. Volume 1: Introduction, keys to the subgenera and species complexes, and the subgenus Camponotus. Mauritius: LAP LAMBERT Academic Publishing, 412 pp.
Smith, M. R. 1965. House-infesting ants of the eastern United States. Their recognition, biology, and economic importance. U.S. Department of Agriculture Technical Bulletin 1326:1–105.
Smith, D. R. 1979. Superfamily Formicoidea. Pp. 1323–1467 in: Krombein, K. V.; Hurd, P. D.; Smith, D. R.; Burks, B. D. (eds.) 1979. Catalog of Hymenoptera in America north of Mexico. Volume 2. Washington, D.C.: Smithsonian Institution Press.
Wernegreen, J. J.; Kauppinen, S. N.; Brady, S. G.; Ward, P. S. 2009. One nutritional symbiosis begat another: phylogenetic evidence that the ant tribe Camponotini acquired Blochmannia by tending sap-feeding insects. BMC Evolutionary Biology 9:292.
Williams, L. E.; Wernegreen, J. J. 2013. Sequence context of indel mutations and their effect on protein evolution in a bacterial endosymbiont. Genome Biology and Evolution 5:599–605.
