# Carpenter ant
**Carpenter ants** are large ants of the genus *Camponotus* (subfamily Formicinae) that excavate nests in wood, usually wood that is moist or softened by decay. They do not eat wood; the damage they cause comes from tunneling galleries for living space, which can weaken structural timbers in buildings[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html). Along with termites, they rank among the most troublesome structural pests in parts of the United States such as [New Hampshire](https://www.edgepedia.org/new-hampshire)[2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet).
| Key fact | Detail |
|---|---|
| Genus | *Camponotus*, subfamily Formicinae; not all species in the genus nest in wood, some use preformed cavities or soil[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [3](https://ask.ifas.ufl.edu/publication/IN1075) |
| Worker size and look | Polymorphic workers, 1/4 to 1/2 inch long, black or bicolored red and black; one petiole node; thorax smooth and evenly rounded from the side[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) |
| Wood relationship | Do not feed on wood; bore galleries into it, usually beginning in wood softened by decay, and pile sawdust-like frass outside the nest[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) |
| Colony structure | Main colony often outdoors in stumps, dead trees, firewood, or fence posts; up to 20 satellite colonies may connect to a main colony holding the queen(s)[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) |
| Diet | Dead and living insects, aphid and scale honeydew, and juices of ripe fruit; they prefer sweets[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) |
| Activity | Forage mostly late in the day or at night, traveling in loose trails; most active between 10 pm and 2 am in Maine observations[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/) |
| Evolutionary age | The tribe Camponotini is estimated to have a crown origin in the Eocene (median 38.4 Ma), with the genus *Camponotus* at 18.6 Ma[5](https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/syen.12678) |
## Identification
Workers are polymorphic, meaning a single nest holds ants of clearly different sizes, and size alone is not a reliable identification character[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [6](https://extension.uga.edu/publications/detail.html?number=B1225&title=biology-and-management-of-carpenter-ants). Useful field marks are the single node on the petiole (the narrow segment between thorax and abdomen), a thorax that is smooth and evenly rounded when viewed from the side, and a strong odor the ants emit when disturbed[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html). Coloring varies by species: many are entirely black, while others are red and black; in New Hampshire, three of the four local species are entirely black and the fourth has a red-brown midsection[2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet).
Winged carpenter ants are frequently confused with winged termites. Termites have straight rather than elbowed antennae, forewings and hindwings of equal size, and no wasp waist behind the legs[7](https://extension.colostate.edu/resource/carpenter-ants/). Confirming a worker to species generally requires a microscope and an entomologist[2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet).
## Nests and damage
Carpenter ants prefer to nest in decayed, often water-damaged wood, and galleries are usually begun in areas where the wood is soft from decay[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [7](https://extension.colostate.edu/resource/carpenter-ants/). Once a nest is established in damp wood, galleries may be extended into sound, dry wood[8](https://extension.umd.edu/resource/carpenter-ants). Damp wood is attractive partly because the ants feed on fungal growth there and the softer fibers make tunneling easier[8](https://extension.umd.edu/resource/carpenter-ants).
The excavations themselves are diagnostic. Carpenter ant galleries look sandpaper smooth and are kept very clean, unlike termite galleries, which are packed with mud and excrement[8](https://extension.umd.edu/resource/carpenter-ants). The ants dump excavated wood particles outside the nest as piles of sawdust-like frass that often include insect parts[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [9](https://extension.psu.edu/carpenter-ants).
Tunneling can cause serious structural damage if it occurs in key timbers, but nest sites rarely exceed a few square feet[8](https://extension.umd.edu/resource/carpenter-ants). When a colony is found within a building, it typically matters most because it indicates that moisture issues are present or have occurred, and near a lasting leak, wood-rotting fungi can pose a structural threat comparable to the ants' own damage.[8](https://extension.umd.edu/resource/carpenter-ants) Indoor nests occur in hollow doors, window or door frames, and the subfloor, and are always associated with moisture[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html).
## Colony life cycle
A colony consists of workers and at least one queen. Workers are sterile, wingless females that gather food and water and gnaw out the galleries in which the colony lives[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/). A single winged female begins a colony by shedding her wings and selecting a nesting site, generally moist wood that has weathered and begun to decay[2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet). The founding queen lays about 30 eggs and cares for the larvae until they become adult workers, after which her full-time job becomes egg-laying[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/).
Mature colonies may contain several thousand individuals[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html). A main colony, often outdoors in a tree stump, dead tree, firewood pile, or fence post, can support up to 20 satellite colonies, and indoor nests are frequently satellites of a larger outdoor nest[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [7](https://extension.colostate.edu/resource/carpenter-ants/).
Two to five years after founding, a colony with a good food supply may produce a reproductive generation of winged males and females. Males are about 5/8 inch long and die shortly after mating; winged females are 5/8 to 7/8 inch long and shed their wings immediately after mating to become queens[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/). Winged ants found indoors in numbers suggest a nest inside the building[8](https://extension.umd.edu/resource/carpenter-ants).
## Diet and behavior
Carpenter ants feed on dead and living insects, aphid and scale honeydew, and juices of ripe fruit, preferring sweets; in forests they also take sap, pollen, nectar, and food scraps, and water is an important part of the diet[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html) • [4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/). Honeydew, the sweet excretion of aphids and certain other insects, is a favorite food[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/).
They travel in loose trails and forage mostly late in the day or at night, preferring moist or humid environments[1](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html). Workers seen wandering indoors during the day, especially in kitchens, are likely foragers from an outdoor nest, a pattern most common in spring and early summer or during drought[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/). Carpenter ants do not sting, though they may rarely bite humans[10](https://extension.unr.edu/small-business-education/pub.aspx?PubID=5493).
## Ecological role
In nature, carpenter ants play a role in recycling wood: they nest in dead trees and their burrowing enhances wood decay[11](https://extensionpubs.unl.edu/publication/g1738/2019/pdf/view/g1738-2019.pdf). Most ant species lack the ability to excavate sound wood, so carpenter ants are unusual in being able to create and expand channels in decomposing wood, a contribution to the channelization and succession of wood decomposition[12](https://sciences.ucf.edu/biology/king/wp-content/uploads/sites/14/2018/05/King-et-al-2018-ants-in-dead-wood.pdf). The closer a forest with rotten logs is to a building, the higher the risk of infestation[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/).
## Evolution and classification
The genus has undergone significant taxonomic revision. Paraphyly in *Camponotus* had been repeatedly indicated, and based on a well-sampled phylogeny, researchers resurrected the genera *Colobopsis* and *Dinomyrmex* for two divergent lineages and redefined *Camponotus* to include *Forelophilus* and *Phasmomyrmex*, making it monophyletic[13](https://pmc.ncbi.nlm.nih.gov/articles/PMC4670518/). A 2025 phylogenomic study of the tribe Camponotini recovered eight major lineages, estimated a crown origin in the Eocene (median 38.4 Ma) for the tribe and 18.6 Ma for *Camponotus*, and inferred an Australasian or Indomalayan origin with multiple dispersals to the Afrotropics, Palearctic, and New World[5](https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/syen.12678).
Biogeographic work on Pacific *Camponotus* related to *C. maculatus* found that Pacific island populations comprise several clades with distinctly different histories, with Australia playing an important role as a source of Pacific colonizations[14](https://pubmed.ncbi.nlm.nih.gov/34772275/).
## Management
Because carpenter ants do not eat wood, control depends on locating the nest rather than on baiting alone. Locating all nests is the most important and difficult step[7](https://extension.colostate.edu/resource/carpenter-ants/). Signs that help include frass piles, faint rustling noises in walls, hollow sounds when suspect wood is tapped, and year-round presence of wingless ants indoors, which indicates an infestation while seasonal presence is less serious[7](https://extension.colostate.edu/resource/carpenter-ants/) • [4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/). Following foraging workers back to the nest, sometimes after offering a sugary substance, can reveal nest locations[6](https://extension.uga.edu/publications/detail.html?number=B1225&title=biology-and-management-of-carpenter-ants).
Preventive measures target moisture and access: repairing plumbing leaks, improving ventilation in crawl spaces and attics, storing firewood away from the house and off the ground, eliminating stumps, and keeping tree branches from touching the structure[2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet). For treatment, dust formulations are the most effective because foraging workers become covered with dust and carry it into the nest[7](https://extension.colostate.edu/resource/carpenter-ants/). Baits labeled for carpenter ants can be part of a control program, though bait cups alone are not an effective approach for serious infestations[4](https://extension.umaine.edu/ipm/ipddl/publications/5007e/) • [2](https://extension.unh.edu/resource/carpenter-ants-fact-sheet).
## References
1. [Carpenter ant, Camponotus spp., UC IPM key to identifying common household ants](https://ipm.ucanr.edu/TOOLS/ANTKEY/carpenter.html)
2. [Carpenter Ants fact sheet, UNH Extension](https://extension.unh.edu/resource/carpenter-ants-fact-sheet)
3. [Florida Carpenter Ants, UF/IFAS Extension SP486C/IN1075](https://ask.ifas.ufl.edu/publication/IN1075)
4. [Carpenter Ants, Pest Management Fact Sheet #5007, University of Maine Cooperative Extension](https://extension.umaine.edu/ipm/ipddl/publications/5007e/)
5. [Ward, P. S., Fisher, B. L., Wernegreen, J. J., Blaimer, B. B. (2025). Evolutionary history, novel lineages and symbiont coevolution in the ant tribe Camponotini. Systematic Entomology 50(3): 646-676](https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/syen.12678)
6. [Biology and Management of Carpenter Ants, UGA Cooperative Extension B1225](https://extension.uga.edu/publications/detail.html?number=B1225&title=biology-and-management-of-carpenter-ants)
7. [Carpenter Ants, Colorado State University Extension](https://extension.colostate.edu/resource/carpenter-ants/)
8. [Carpenter Ants, University of Maryland Extension](https://extension.umd.edu/resource/carpenter-ants)
9. [Carpenter Ants, Penn State Extension](https://extension.psu.edu/carpenter-ants)
10. [A Northern Nevada Homeowner's Guide to Identifying and Managing Carpenter Ants, University of Nevada, Reno Extension](https://extension.unr.edu/small-business-education/pub.aspx?PubID=5493)
11. [Carpenter Ant Management, Nebraska Extension NebGuide G1738](https://extensionpubs.unl.edu/publication/g1738/2019/pdf/view/g1738-2019.pdf)
12. [King, J. R. and colleagues (2018). Ants in dead wood, chapter in Springer volume, doi 10.1007/978-3-319-75937-1_8](https://sciences.ucf.edu/biology/king/wp-content/uploads/sites/14/2018/05/King-et-al-2018-ants-in-dead-wood.pdf)
13. [Ward, P. S. and colleagues (2015). Phylogenomic methods outperform traditional multi-locus approaches in resolving deep evolutionary history: a case study of formicine ants. Systematic Entomology (PMC4670518)](https://pmc.ncbi.nlm.nih.gov/articles/PMC4670518/)
14. [Molecular phylogeny of Indo-Pacific carpenter ants reveals waves of dispersal and colonization from diverse source areas (PubMed 34772275)](https://pubmed.ncbi.nlm.nih.gov/34772275/)
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*Topic: Encyclopedia › Life and health › Animals › Invertebrates › Arthropods › Insects › Bees, wasps, and ants › Aculeata: bees, wasps, and ants › Ants (Formicidae)*
*Initially written Sep 17, 2026 · Reviewed: Oct 21, 2026 · Edited: Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license