Camponotus pennsylvanicus

This species is the first North American ant to be described. It nests in living and dead trees, rotten logs or stumps in forested areas. This is an important, destructive pest that attacks fences, poles and buildings. This is probably the most destructive carpenter ant in North America (Wheeler and Wheeler 1963), although Creighton (1950) argued that its destructive capacities were somewhat exaggerated and that they only tunnel in decayed wood. It often forages inside homes, making it an important house pest. Reproductives were found in nests from April to October. This species is found in the same logs and stumps as members of the genera Lasius, Formica (i. e. Formica podzolica), and Leptothorax. Workers tend aphids, with the smaller workers collecting honeydew and transferring it to larger workers that carry it back to the nest. In addition, foragers feed on dead insects and plant juices.

Compare with Camponotus chromaiodes, Camponotus modoc, Camponotus herculeanus, Camponotus novaeboracensis, Camponotus schaefferi, Camponotus texanus.

The majors, minors, females and males of C. pennsylvanicus are black ants without erect setae on the cheeks or sides of the head, or posterior lateral corners, the scapes are without erect and suberect setae, except at the apex, but the mesosoma has numerous setae on the dorsal surface, as does the petiole. The gaster has erect and suberect setae scattered over the entire surface, the tibiae are without erect and suberect setae, except for 2 rows along the flexor surface, in which most setae are present along the distal half. Appressed pubescence is sparse on most surfaces, including the head and mesosoma, although the setae on the dorsum are more numerous, but non-overlapping or few overlap adjacent setae, the side of the propodeum has a few appressed setae.

The appressed or decumbent setae on the gaster are long (over 0.2 mm) and abundant, nearly all setae overlap adjacent setae and are nearly as long as the erect and suberect setae on the gaster. The appressed setae on the gaster of the minors and especially the females may be small and may not overlap adjacent setae.

Comparisons
Camponotus pennsylvanicus is a member of a small group of 4 similar species (together with Camponotus modoc, Camponotus herculeanus and Camponotus chromaiodes), which are difficult to separate. It has been shown to be genetically similar to C. modoc (Sämi Schär, et al., 2018). Majors of C. pennsylvanicus may be separated from those of Camponotus modoc (S Canada, mostly W US and N Mexico) as the appressed setae on the gaster of C. pennsylvanicus are nearly as long or as long as the erect and suberect setae (usually over 0.15 mm), whereas these setae on Camponotus modoc are generally shorter than ½ the length of the erect and suberect setae (usually less than 0.15 mm). The appressed setae on the gaster of C. pennsylvanicus overlap adjacent setae, whereas they rarely do in C. modoc. Unfortunately, the length of the appressed setae in these two species varies geographically, with the shortest setae being found at lower latitudes and higher longitude (west and north), the longer setae found at higher latitudes and lower longitudes (south and east, Fig. 256), further complicating the separation of the two species. The gradient suggests that they are both the same species, but as members of a single colony have appressed setae of similar lengths, and both species can be found at specific localities therefore they will be considered two species, until other evidence becomes available.

Camponotus pennsylvanicus can also be confused with Camponotus herculeanus (S Canada, US), but is nearly always concolorous black, whereas Camponotus herculeanus generally has a deep red mesosoma, or at least deep red legs. Along the western edge of the distribution (Wyoming south to northern New Mexico) specimens usually have red legs, which may be evidence of hybridization. The scape of the major of C. pennsylvanicus extends 1 - 2 funicular segments past the posterior lateral corner of the head, whereas the scape of majors of C. herculeanus rarely reaches the posterior lateral corner or extends less than 1 funicular segment past it. The appressed setae on the gaster are much denser in C. pennsylvanicus than in C. novaeboracensis. A single major from Ames, Iowa has short scapes (as in C. herculeanus) and long appressed pubescence, typical of C. pennsylvanicus. It could be a hybrid but is considered a member of the latter species.

Camponotus pennsylvanicus and Camponotus chromaiodes co-occur in Douglasville, Pennsylvania, suggesting that they are valid species. The majors appear to differ only in color, with the anterior edge of the gaster of C. pennsylvanicus being black instead of reddish as in C. chromaiodes.

The minors of the 4 species are very difficult to separate. The minors of Camponotus pennsylvanicus are usually concolorous black, whereas at least the legs of Camponotus modoc and Camponotus herculeanus are often dark red, and the minor of C. chromaiodes is bicolored, black with a red first tergum of the gaster, and the mesosoma is partially or even completely red. The appressed setae of C. modoc and C. herculeanus are usually shorter than they are in C. pennsylvanicus and C. chromaiodes.

The females of the 4 species often cannot be reliably separated as the appressed setae on the gaster of C. pennsylvanicus are often short and similar to those of C. modoc and C. herculeanus. The females of Camponotus pennsylvanicus are concolorous black, whereas the legs of the other 2 species are occasionally dark red. The female of C. chromaiodes is dark, but at least the anterior edge of the first gastral tergum is red, and the lower part of the mesosoma is often red. The scapes extend about the same distance past the posterior lateral corners of the head of the female in all 4 species (about 2 funicular segments past the posterior border of the head).

The males of the 3 species apparently cannot be distinguished and in general cannot be separated from most other species of Camponotus.

The clypeus of C. pennsylvanicus has weakly developed angles along the anterior border, similar to those of Camponotus schaefferi (AZ, NM) and Camponotus texanus (W TX). It can be easily separated as the side of the mesosoma is dull and punctate, not nearly smooth and glossy as in the latter two species.

Camponotus pennsylvanicus can be confused with Camponotus novaeboracensis (S Canada, US). They can be separated as the workers and often the females of C. novaeboracensis are bicolored, whereas they are nearly always concolorous black in C. pennsylvanicus. Questionable specimens can be separated as the setae on the gaster of workers and of the females of C. pennsylvanicus are longer and most overlap adjacent setae, whereas in C. novaeboracensis they are relatively short, with few or no appressed setae overlapping adjacent setae. Unfortunately, neither of these characteristics serve to separate the males, and there are no obvious characters which will separate them. Camponotus pennsylvanicus is sympatric with C. novaeboracensis in Iowa with no integration which suggests they are separate species (Buren, 1944).

Camponotus pennsylvanicus is founds in areas with clay or sandy brown soils. It is found in a variety of plant communities ranging from urban habitats, desert scrub with few creosote bushes, bocage farmland, grasslands, pine/spruce surrounded by grassland, oak dominated forest with palmetto understory, riparian weedy areas,  riparian hardwood forests, deciduous forest, bottomland forest, mixed hardwood forest, mixed hardwood/conifer forest, ponderosa pine with few pinyon pines, second growth pines/hardwoods, oak woodland, hardwood/oak woodlands,  oak evergreen forest wetlands, pine, elm cottonwood, larch forests and beach/conifer forest.

It is a habitat generalist that remains in urban forests in Canada (Thompson and McLachlan, 2007) and is found in urban habitat (Guénard et al., 2015). Wheeler and Wheeler (1963) and Oberg (2012) reported it from wooded areas. It is also found in open areas and deciduous and mixed forest (MacGown and Brown, 2006), including witch-hazel-red maple forests (Yitbarek et al, 2011), as well as grasslands and shrublands (Barber, 2015).

It is also found in marsh/emergent wetland, pocosin, swamps and bottomland hardwood, recently cleared land, upland pine, pine woodland/longleaf pine savanna, maritime forest, upland mixed forest, and grassland (Davis, 2009).

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

Camponotus pennsylvanicus, the black carpenter ant, was the first North American ant to be described. Smith (1965) summarized what had been published and supplemented the summary with personal observations. He concluded it is one of our best known and most adaptable ants.

It nests almost exclusively in wood. Camponotus pennsylvanicus nests in many different species of trees, as well as in telephone poles; one nest was 75 feet up in a tree. Single females form their nests in preformed or self-formed cavities, usually under bark of a log or stump, and each nest has a single queen. There are approximately 2000 or more workers in a three to six-year-old nests. Development takes 60 days. Nuptial flights from overwintering sexuals occur from May to late July. Foragers are diurnal and nocturnal, feeding on living and dead insects. They collect honeydew from plant lice and treehoppers, as well as the juices of fruits and sap of certain plants. Forgers commonly feed on foods found in kitchens. It produces a lot of damage to wooden structures and destroys food in houses, especially when it is brought into houses with firewood. Camponotus pennsylvanicus is parasitized by at least two species of phorid flies, and three species of fungi.

Other researchers and our own experience add details to the biology of Camponotus pennsylvanicus. This is the common black carpenter ant, which is fond of nesting in logs, stumps, trees, etc. in South Carolina (Smith, 1934). It nests in living and dead trees, in /under bark of logs under rotten logs or in stumps, under bark of dead trees, in living cottonwood trees and rarely in soil under stones, as well as wooden structures ranging from telephone poles to buildings. It nests in rotten logs and in soil at the base of Quercus pagoda (MacGown and Brown, 2006).

It prefers mature hardwood (Quercus spp.) trees approximately 30 cm in diameter and pine logs (Pinus spp.) that were approximately 9 m in length. Defects in trees most often associated with nests included tree holes and crotches (Oswalt, 2007). One nest was in stack of newspapers in a box in a garage, two were from building walls (Wheeler and Wheeler, 1963).

Camponotus pennsylvanicus is unable to actively regulate its internal nest environment but can use the insulative properties of trees to dampen wide temperature fluctuations and provide a more stable nest microclimate (Oswalt, 2007). The internal nest temperature of occupied nests mirrored unoccupied nests throughout the year and differences were not statistically significant (Oswalt, 2007). In warm sites, C. pennsylvanicus tends to occupy relatively cool chambers (Diamond et al., 2012). They seal the nest during the winter, lose half of the fat reserves during the winter and fill their bodies with glycerol as antifreeze, freezing at temperatures as low as -22°C (Ellison et al., 2012).

Mature colonies can be large with 2000-2500 adults (Hölldobler and Wilson 1990) and may reach 10,000-15,000 workers (Hansen and Klotz 2005; Ellison et al., 2012) and are facultatively or weakly polydomous (Buczkowski, 2011).

Camponotus pennsylvanicus brood were found in nests from April to August; sexuals from April to October (Mackay and Mackay, 2002). Reproductives overwinter in nests (Buren, 1944).

Flights of C. pennsylvanicus occur in May, and sexuals can be captured in black light traps. Females start nests in or under logs, or under bark (Buren, 1944) in May and July; occasionally more than a single female may be found together.

Sanders (1972) studied foraging in C. pennsylvanicus and found that the start of seasonal activity was temperature dependent (Stuble et al., 2014), and activity peaked in mid-summer. Later in the season they became virtually nocturnal or are in general primarily nocturnal (Hansen and Klotz, 2005) when the weather becomes too hot (Klotz, 1984). Nuss et al. (2005) report that most foraging of C. pennsylvanicus is nocturnal and crepuscular.

The black carpenter ant tends honeydew producers and scavenges for dead insects and plant material and can be captured in surface baits. They are honeydew feeders (Oberg, 2012), tending aphids (Jones, 1929) and the calico scale Eulecanium cerasorum (Vanek and Potter, 2010). Cannon and Fell (2002) report on the macronutrients collected by foragers of Camponotus pennsylvanicus under natural conditions. Trophallaxis boosts disease resistance within the colony (Hamilton et al, 2010).

Oswald (2007) completed a series of feeding experiments. Camponotus pennsylvanicus selected a higher concentration of sucrose as the distance from a food patch to the nest increased to 15 m. Foragers imbibed sucrose from both concentrations at 1 m with no preference noted between the two solutions. Mean feeding durations indicated that foraging black carpenter ants fed deferentially on casein solutions, depending on concentration or distance. Overall casein mean feeding time was significant, suggesting C. pennsylvanicus feeds longer on 30% casein solution regardless of the distance involved. Additional analysis indicated that the effect of distance on feeding duration was only significant at a 5% solution concentration. Overall mean feeding time was significant, suggesting feeding intervals were greater on 30% casein over both distances (Oswalt, 2007).

Camponotus pennsylvanicus is important in seed removal (Stuble et al., 2014) and preys on the red oak borer Enaphalodes rufulus (Coleoptera: Cerambycidae) (Muilenburg et al., 2008; Verble and Stephen, 2009).

Foragers are aggressive (Stuble et al., 2014), and patrol bracken fern (Pteridium aquilinum) during the sensitive crozier growth stage (Oberg, 2012) and remove herbivorous insects from rapidly expanding fronds (Oldenkamp and Douglas, 2011). They removed seeds from bait stations (Warren et al., 2010). Scout ants recruit nestmates to a new food source using alerting motor displays (Traniello, 1977). The nest mates follow a recruitment trail that is apparently composed of materials from the hindgut and poison gland (formic acid). The pheromone is produced by the hindgut and the trails consist of streaks, that are not reinforced by gorged workers passing over them (Hartwick et al., 1977). They show topochemical learning in which the foragers navigate using preexisting chemicals of plant substrates (Helmy and Jander, 2003). When a strong direct light is available, the workers use light orientation and stop making trails (Hartwick et al., 1977).

Camponotus pennsylvanicus is a behaviorally dominant ant (Oberg, 2012), and the most common carpenter ant in New England (Ellison et al., 2012). There was a strong negative association between the congeners Camponotus novaeboracensis and C. pennsylvanicus (Thompson and McLachlan, 2007). The proportion of trees colonized by C. pennsylvanicus was significantly higher in urban plots (with fewer trees), suggesting that intraspecific competition for nesting sites may be especially high in areas with lower tree density (Buczkowski, 2011). Del Toro et al. (2013) found it to be a neutrally interacting species found mainly in forested plots.

Camponotus pennsylvanicus is the host of the endosymbiotic proteobacteria Candidatus Blochmannia (Sauer et al, 2000; Degnan et al., 2004), which has close relatives that occur in aphids and the tsetse fly (Sauer et al, 2000). The bacteria apparently lack abilities to replicate outside of host cells, and the insect hosts depend on endosymbiont functions that are often nutritional in nature (Wernegreen, 2015).

They carry phoretic mites (Campbell et al., 2013), are an alternate host for Nemadus triangulum (Coleoptera: Leiodidae) and a minor host for N. parasitus (Peck and Cook, 2007). Reemer (2012) discusses the parasitism by the syrphid fly parasite Microdon sp. and C. pennsylvanicus is specifically the host of Microdon cothurnatus (Duffield, 1981). They are not infected by the fungus Ophiocordyceps unilateralis sensu lato, whereas Camponotus americanus and Camponotus castaneus were (de Bakker et al., 2014).

Camponotus pennsylvanicus is one of the major ant pests in the United States (Santos, 2016) and one of the four most common house infesting ants in Illinois (Walker, 2013). Hansen and Klotz (2005) conclude that it is the principal structural pest in eastern North America. It causes damage to buildings and forages in homes, and also attacks fences, poles and buildings (Wheeler, 1905a). Buren (1944) found it in beams of frame houses. The nest is often outside 200-300 meters away from a home so it is not easily exterminated (Ellison et al., 2012). This species may bite but generally avoids confrontation (Forester, 2003).

Additional Notes
In southern New England this species is one of the most abundant and adaptable species across a wide range of forest habitats.

Wheeler (1910) - C. pennsylvanicus ranges over southern Canada and the states as far west as Victoria, Texas, and the Pine Ridge Indian Reservation in South Dakota. Unlike whymperi and modoc it is a lowland form. It is far and away the most abundant Camponotus in the North Atlantic states and Middle West, showing a range of adaptability to differences in temperature and humidity second only to that of Lasius americanus and Formica subsericea. On this account, it is the only one of our Camponoti that has attracted general attention. It is commonly found nesting in old logs and stumps or in the dead wood of standing trees, but occasionally it nests in old houses. In such places it may do considerable damage by tunneling in beams and rafters and may become a domestic nuisance by visiting the sweet food-stuffs in kitchens and pantries. Its habits were first studied by McCook. Recently Pricer and Miss Edith Buckingham have made many interesting observations on its polymorphism and behavior.

Gripshover et al. (2018) examined the mechanics of how workers of this species are able to move through water.

Morphology
Draft et al. (2018) - A study of antenna olfactory behavior. Abstract:Directed and meaningful animal behavior depends on the ability to sense key features in the environment. Among the different environmental signals, olfactory cues are critically important for foraging, navigation and social communication in many species, including ants. Ants use their two antennae to explore the olfactory world, but how they do so remains largely unknown. In this study, we used high-resolution videography to characterize the antennae dynamics of carpenter ants (Camponotus pennsylvanicus). Antennae are highly active during both odor tracking and exploratory behavior. When tracking, ants used several distinct behavioral strategies with stereotyped antennae sampling patterns (which we call 'sinusoidal', 'probing' and 'trail following'). In all behaviors, left and right antennae movements were anti-correlated, and tracking ants exhibited biases in the use of left versus right antenna to sample the odor trail. These results suggest non-redundant roles for the two antennae. In one of the behavioral modules (trail following), ants used both antennae to detect trail edges and direct subsequent turns, suggesting a specialized form of tropotaxis. Lastly, removal of an antenna resulted not only in less accurate tracking but also in changes in the sampling pattern of the remaining antenna. Our quantitative characterization of odor trail tracking lays a foundation to build better models of olfactory sensory processing and sensorimotor behavior in terrestrial insects.

Nomenclature

 *  pennsylvanicus. Formica pensylvanica De Geer, 1773: 603, pl. 31, figs. 9, 10 (s.w.q.m.) U.S.A. [Spelling justifiably emended to pennsylvanica: Buckley, 1866: 155.] Wheeler, G.C. & Wheeler, J. 1953e: 187 (l.). Combination in Camponotus: Mayr, 1862: 666; in C. (Camponotus): Forel, 1914a: 266. Subspecies of herculeanus: Forel, 1879a: 57; Mayr, 1886d: 420; Wheeler, W.M. 1913c: 117; Wheeler, W.M. 1917i: 465; Wheeler, W.M. 1932a: 13; Buren, 1944a: 293. Status as species: Ruzsky, 1896: 67; Forel, 1901h: 70; Forel, 1907e: 10; Wheeler, W.M. 1910d: 335; Emery, 1920b: 255; Creighton, 1950a: 367; Smith, D.R. 1979: 1427. Senior synonym of semipunctata: Mayr, 1886d: 420; of herculeanopennsylvanicus (and its junior synonym mahican): Creighton, 1950a: 367.
 * herculeanopennsylvanicus. Camponotus herculeanus var. herculeanopennsylvanicus Forel, 1879a: 57 (w.) U.S.A. Senior synonym of mahican (unnecessary replacement name): Emery, 1925b: 72. Junior synonym of pennsylvanicus: Creighton, 1950a: 367.
 * mahican. Camponotus herculeanus var. mahican Emery, 1925b: 72 (s.w.) U.S.A. [First available use of Camponotus herculeanus subsp. pennsylvanicus var. mahican Wheeler, W.M. 1910d: 338; unavailable name.] Unnecessary replacement name for herculeanopennsylvanicus and hence junior synonym of the latter: Bolton, 1995b: 110. See also: Creighton, 1950a: 367; Smith, M.R. 1951a: 842.

Major worker measurements (mm): HL 2.62 - 3.16, HW 2.68 - 3.34, SL 2.58 - 2.84, EL 0.59 - 0.73, CL 0.89 - 1.04, CW 1.13 - 1.34, WL 3.70 - 4.20, FFL 2.36 - 2.66, FFW 0.70 - 0.89. Indices: CI 102 - 106, SI 90 - 98, CLI 127 - 129, FFI 30 - 33.

Mandibles with 5 teeth; anterior border of clypeus weakly concave; sides of head narrowed anteriorly, convex, posterior margin concave; eyes failing to reach sides of head by about ½ - 1 minimum diameter; scape extending 1 - 2 funicular segments past posterior lateral corner of head; propodeum weakly angulate between 2 faces, which are about equal in length, propodeal spiracle elongate; petiole narrow in profile, apex rounded and convex as seen from behind. Erect and suberect setae sparse on most surfaces, present on clypeus, mostly along margins, present along frontal carinae extending back to posterior margin, absent on cheeks, sides of head, posterior lateral corners, scapes (except apex), few setae scattered on ventral surface of head, numerous on mesosoma, petiole and gaster; appressed setae sparse on head, present on dorsum of mesosoma down along upper edge of propodeum, very abundant on gaster, touching adjacent setae.

Most surfaces dull, head densely and evenly punctate, with scattered larger punctures, mesosoma punctate, merging to coriaceous on dorsum of mesosoma, gaster very finely punctate, with scattered larger punctures. Concolorous black.

Minor worker measurements (mm): HL 1.58 - 2.56, HW 1.24 - 2.34, SL 1.86 - 2.56, EL 0.41 - 0.59, CL 0.48 - 0.81, CW 0.73 - 1.06, WL 2.28 - 3.48, FFL 1.56 - 2.36, FFW 0.48 - 0.70. Indices: CI 78 - 91, SI 100 - 118, CLI 131 - 153, FFI 30.

Similar to major worker, except eyes come within ½ minimum diameter of the side of the head, sides of head weakly narrowed anteriorly, posterior margin nearly straight to rounded, scapes extending about ½ length past posterior lateral corner of head.

Pilosity sculpture and color as in major worker.

Female measurements (mm): HL 3.10 - 3.52, HW 3.38 - 3.80, SL 2.82 - 2.90, EL 0.80 - 0.89, CL 0.95 - 1.14, CW 1.31 - 1.40, WL 5.66 - 5.70, FFL 2.76 - 2.86, FFW 0.76 - 0.91. Indices: CI 108 - 109, SI 82 - 91, CLI 123 - 138, FFI 28 - 32.

Mandible with 5 teeth; clypeus weakly concave anteriorly, lateral angles poorly developed; head narrowed anteriorly, posterior margin nearly straight to convex; eyes failing to reach sides of head by less than 1 minimum diameter; scape extending 1 or 2 funicular segments past posterior lateral corner of head; propodeal spiracle elongate, narrow; petiole narrowed as seen in profile, apex moderately sharp.

Erect and suberect setae sparse, present along margins of clypeus, setae along frontal carinae extend to posterior margin, absent on posterior lateral corners, sides of head, scapes (except apex), few setae on dorsum of mesosoma, on petiole and dorsal surface of gaster; appressed pubescence sparse, few tiny setae on head and dorsal surface of mesosoma, those on gaster longer (0.01 - 0.02 mm), but shorter than setae of major.

Sculpture and color as in major worker.

Male measurements (mm): HL 1.58 - 1.70, HW 1.42 - 1.54, SL 1.74 - 2.04, EL 0.54 - 0.60, CL 0.36 - 0.45, CW 0.71 - 0.79, WL 3.64 - 3.82, FFL 2.26 - 2.46, FFW 0.46 - 0.51. Indices: CI 88 - 91, SI 110 - 126, CLI 175 - 197, FFI 20 - 21.

Black specimen, which apparently possesses no characteristics that would separate it from those of other similar species.

References based on Global Ant Biodiversity Informatics

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