As indicated by their common name, black carpenter ants are black in color. They have one petiole, which is the space between their thorax and abdomen body segments. Like some other ant species, black carpenter ants are polymorphic, which means that members of this species can have several different sizes and forms, including small (minor) workers, large (major) workers and queens. Black carpenter ants are one of the largest species of carpenter ants; large workers are about 0.5 to 1.6 cm long and queens are about 1.9 cm long. Males and breeding females have wings, although workers are wingless and queens lose their wings once they establish a new colony. Unlike other ant species, black carpenter ants have distinctive hairs on their abdomen. (Fowler, 1984; Morgan, 1997; Ogg, 2013)
Black carpenter ants are native to the eastern half of the United States; they are the most common members of their genus (Camponotus) in this region. They are also present in eastern Canada. (Buczkowski, 2011; Sanders, 1972; Verble and Stephen, 2009; Wetterer and Wetterer, 2004)
Black carpenter ants nest in deciduous trees, decaying logs and wooden buildings in urban and suburban areas, such as in grassy areas between buildings or in parks. Their nests can also be found in open areas such as agricultural fields, meadows and grasslands; they may also nest along rivers. (Buczkowski, 2011; Carney, 1969; Inayat, et al., 2012; MacGown and Brown, 2006; Oberg, et al., 2012; Verble and Stephen, 2009)
Ants are holometabolous, which means that they undergo complete metamorphosis, going through an egg, larvae, pupae and adult stage. Eggs hatch after about 18 to 25 days, after which ants enter a larval stage for 14 to 25 days. Larvae are cared for and fed by adult workers. Larvae then spin cocoons and become pupae. After about 25 days, they emerge as adults. Eggs that hatch in the late summer spend the winter as larvae, typically for about 6 months. (Cannon and Fell, 1992; Gibson and Scott, 1990)
Males and winged females perform their mating rituals in the summer, usually in July. During this time, the ants perform nuptial flights. This begins when males produce a pheromone that encourages females to fly and find mates, which causes swarms of several females. After mating, each female leaves to begin a new colony with her newly fertilized eggs. These queens lay their eggs inside holes or knots in trees, they take care of them until they hatch, metamorphose and become her workers. After which, these workers take care of any new batches of eggs and help increase the size of the nest. Males do not return to the colony and die shortly after mating. Breeding females and males are not produced until several years after the parent colony has been created. (Forbes, 1956; Fowler and Roberts, 1982a; Loiacono and Margaria, 2003)
Black carpenter ants lay eggs twice a year, eggs laid in the spring produce workers, while eggs laid in August and September produce mating ants. Eggs laid in the late summer hatch and spend the winter as larvae, becoming workers during the following June and July. When a queen begins a new colony, she first lays 5 to 15 eggs, which produce workers. Beginning in her second-season, queens lay larger batches of eggs. Queens store the sperm from their first mating and continue to lay eggs throughout their lifetime. Fertilized eggs become female workers, while unfertilized eggs become males. Males are produced seasonally and have half as many chromosomes as females. Most females are non-breeding workers, but when conditions are good, sexually reproductive winged females are produced. (Cannon and Fell, 2002; Gibson and Scott, 1990; Loiacono and Margaria, 2003)
When the eggs of black carpenter ants hatch, the offspring remain in the nest as larvae and pupae and join the colony ranks when they reach adulthood. Workers give protection and care for the larvae, bringing food from outside the nest and feeding larvae by trophallaxis, a process that involves the regurgitation of food stored in their crop. (Fowler, 1983)
The lifespan of black carpenter ants depends on their position in the nest. Queens can live for over 10 years, whereas males die shortly after mating so their lifespan is likely a few weeks to a few months. Sterile female workers can live for a few months up to 7 years or more. (Loiacono and Margaria, 2003; Morgan, 1997)
Black carpenter ants live in large colonies in nests built within trees, dead logs or wooden buildings. Their nest population size is not known, but other ant species can have 1,000 to 100,000 individuals in a colony. Black carpenter ants have defined roles within their colony. A queen lays eggs and other workers tend to her. Smaller or minor workers tend to aphids and collect the sugary honeydew that they produce. Larger or major workers are more involved with maintaining the nest, expanding the nest by chewing wood and defending colony resources. Middle- to large-sized workers also care for the larvae. Males have short lifespans and do little more than find a mate. Winged females find mates and establish new colonies. These ants are mainly nocturnal and collect most of their food at night or right after sunset. They generally lay low and do not forage in mid-afternoon, the hottest part of the day. Ants stay in their nest during the winter and remain inactive while the temperature is below 5 degrees Celsius. Because they are built inside logs or tree trunks, their nests stay warm all year. Ants in laboratory colonies kept at a constant temperature throughout the year become sluggish during the winter, but they continue to forage. (Boroczky, et al., 2013; Buczkowski, 2011; Cannon and Fell, 1992; Cannon and Fell, 2002; Fowler, 1983; Helmy and Jander, 2003; Verble and Stephen, 2009)
Most colonies of black carpenter ants have parent nests and several other satellite nests. In one colony, their range area was between 6 and 28 square meters, occupying 1 to 6 trees in that area including the parent and satellite nests. (Buczkowski, 2011; Klotz and Reid, 1993)
Black carpenter ants use their antennae for smelling, detecting chemicals, understanding their environment and communicating with others. Vision and chemical detection are their most important senses. Scouts leave the colony and search until they find a food source. They eat until they are satisfied, then they leave a chemical trail back to the nest for others to following by moving the tip of their abdomen along the ground. Scouts announce the food source to the colony by a wiggling dance display, vibrating their head and thorax back and forth. Scouts attempt to alert the whole colony of the food source and may offer the food to other colony members. After a food offering, ants often make contact such as knocking antennae and forelegs against one another. Because they forage mostly at night, chemical trails are very important; they may also use other cues such as tree roots or cracks in cement. Black carpenter ants also have glands that produce formic acid. This acid can act as an alarm signal to other ants and in low doses can attract ants to trails. Queens produce a pheromone that attracts workers and attendants to care for her. Males also produce pheromones to begin the mating process. (Boroczky, et al., 2013; Fowler and Roberts, 1982b; Helmy and Jander, 2003; Hillery and Fell, 2000; Klotz and Reid, 1993; Traniello, 1977)
Black carpenter ants are omnivorous. Although this species builds their nests in trees and decaying wood, they do not actually feed on wood. They prey on many insect species, including aphids and occasionally butterfly and moth larvae. Black carpenter ants farm aphids, eating the honeydew that aphids produce. They are also noted predators of many forest pests and may have played a role in the significant population decline of red oak borers. They also eat plant nectar, fruit and some fungi. Black carpenter ants often scavenge food or trash left behind by humans, eating almost anything, including honey, tuna fish, hot dogs and cookies. (Cannon and Fell, 2002; Hamilton, et al., 2011; Helmy and Jander, 2003; Inayat, et al., 2012; MacGown and Brown, 2006; Oberg, et al., 2012; Tripp, et al., 2000; Verble and Stephen, 2009; Youngsteadt and Devries, 2005)
Little information is available regarding predation of black carpenter ants. Insectivorous birds found in the eastern half of the United States are likely predators, but the nocturnal foraging of black carpenter ants helps them avoid bird predation. When provoked, carpenter ants lunge forward with their mandibles held apart. They may fight with colonies of other carpenter ant species, particularly Camponotus herculeanus, although these fights usually result in the mutilation and death of many workers, rather than predation. (Carney, 1969; Klotz, et al., 1998; Sanders, 1964)
Black carpenter ants are likely prey for several bird species. Ants with the parasitic fluke, Brachylecithum mosquensis, are more easily caught by birds because they become sluggish, obese and act odd. Parasitoid phorid flies, Apocephalus concisus and Trucidophora camponoti, also parasitize black carpenter ants by laying their eggs inside of the ants, killing the ants when they hatch. Likewise, the fungus Ophiocordyceps unilateralis can grow on the ants, killing them. Black carpenter ants prey on aphids, spiders and many forest pest species. Some colonies farm wooly alder aphids, eating the honeydew they produce and protecting aphids from predators. Blochmannia pennsylvanicus is a proteobacterium found inside the ants, which helps them process nitrogen. Finally, because black carpenter ants nest in decaying wood, they help biodegradation, or break down old materials. (Brown, 2002; Brown, et al., 1991; Carney, 1969; Gosalbes, et al., 2010; Inayat, et al., 2012; Morgan, 1997; Oberg, et al., 2012; Van Pelt, 1958; Youngsteadt and Devries, 2005)
Black carpenter ants are the most significant structural pest in urban areas of the eastern United States. Because they colonize trees and decaying wood, these ants can invade the wooden structures of houses and other buildings as they tunnel, potentially causing severe damage. Wooden structures that are prone to moisture tend to be most at risk of infestation. Millions of dollars are estimated to be spent each year in attempts to eliminate their nests and prevent damage. Much research has been conducted to determine the most effective insecticides and other means of controlling their populations. (Buczkowski, 2011; Klotz, et al., 1996; Morgan, 1997; Ogg, 2013; Tripp, et al., 2000)
Black carpenter ants prey on many insect species that are pests to humans, including aphids and termites, which can decrease damage to crops and buildings. They do not, however, offer a significant method of pest control. (Morgan, 1997)
Black carpenter ants have no special conservation status.
Angela Miner (author), Animal Diversity Web Staff, Elizabeth Wason (editor), Animal Diversity Web Staff, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
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