Carpenter ants are large ants that can cause significant damage to wood in homes and other structures. While there are several different species of carpenter ants, they can generally be identified by a few key characteristics.
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Appearance
Carpenter ants are large, measuring 0.3 to 1.25 inches (0.75 to 3 cm) in length. They are black or red and black in color. The most common species in the United States is the black carpenter ant, which is solid black in color. Red carpenter ants have dark red or reddish-black bodies with black abdomens. Carpenter ants have a node-like appearance, with the narrow “waist” between the abdomen and thorax. The antennae are elbowed. Carpenter ants can be distinguished from termites as their waists have one node, while termites have two.
Size
Carpenter ants range in size from 5 to 15 mm (0.2 to 0.6 inches). Workers are approximately 6 mm, minor workers are 5 mm, media workers are 8 mm, major workers are 10 to 12 mm, and reproductives can reach 15 mm. Queens are the largest at 15 mm.
Color
Most carpenter ants are black or have a black abdomen with a reddish head and thorax. However, there are regional color variations:
- Black carpenter ants are solid black and the most common species in the eastern US
- Red carpenter ants have dark red/reddish-black bodies and black abdomens
- Western carpenter ants are black with pale yellowish markings on the thorax
- California carpenter ants are brownish-black overall
- Florida carpenter ants are the largest and are solid black
Markings
Carpenter ants do not have the elbowed antennae or distinctive node-like waist that separates the abdomen and thorax like carpenter ants do. They may be solid black or have some pale yellowish or reddish markings.
Behavior
Carpenter ants exhibit some key behaviors that can help identify them:
- Carpenter ants produce a distinctive “reproductive swarm” of flying ants from mature nests in the spring.
- Forage in a meandering trail along the edges of structures.
- Primarily search for food at night along trails.
- Nest in moisture-damaged wood, especially softer woods like pine, cedar, cypress, and douglas fir.
- Do not eat the wood, but excavate galleries and tunnels to nest in.
- Push sawdust and debris out small holes or cracks in damaged wood.
Signs of Infestation
Signs that carpenter ants may be nesting in a structure include:
- Seeing winged carpenter ants swarming indoors or gathering around lights
- Small piles of coarse sawdust around cracks or nail holes
- Hollow sounding damaged wood when tapped
- Frass (insect waste) piles near nest sites
- Carpenter ants foraging in meandering trails on the structure exterior
Nesting Habits
Carpenter ants create extensive galleries and tunnels by excavating wood. Some key facts about their nests:
- Prefer softer, moisture-damaged wood
- Main nest sites are typically outdoors in tree stumps, logs, landscaping timbers, wooden patio furniture, etc.
- Satellite nests may be excavated indoors in exposed wood when nests are mature
- Nests contain scattered chambers and tunnels
- Tunnel openings are perfectly rounded and smooth
- Tunnel doors may remain thin to allow light into the nest
Wood Damage
Unlike termites, carpenter ants do not actually consume wood. They excavate it to make room for nesting galleries and tunnels. Some signs of carpenter ant damage include:
- Tunnels and hollowed voids in wood structures
- Thin, papery external layers of wood left intact
- Polished, very smooth tunnel walls
- Coarse sawdust and debris left in or near nest sites
- No mud tubes as seen with subterranean termites
- Possible staining or discoloration from carpenter ant waste
Differences from Termites
While both carpenter ants and termites damage wood, there are some noticeable differences:
| Carpenter Ants | Termites |
|---|---|
| Excavate wood to make nest galleries | Consume and digest wood for nutrition |
| Leave coarse sawdust | Leave fine, powdery pellets |
| Do not consume wood | Actually eat the wood |
| Polished, smooth tunnels | Muddy tubes connecting food to nest |
| No mud tubes | Build protective mud tubes |
| Solitary colonies | Colony networks with satellite nests |
| Has elbowed antennae | Straight antennae |
| Broad waist with one node | Pinched waist with two nodes |
Carpenter Ant Species
There are several different species of carpenter ant in the United States and North America:
Black Carpenter Ant (Camponotus pennsylvanicus)
- Most common eastern US species
- Large and completely black
- Nest in dead trees and logs outdoors
- Sometimes nest in houses near moisture damage
Red Carpenter Ant (Camponotus ferrugineus)
- Most prevalent west of the Rocky Mountains
- Reddish head and thorax with dark abdomen
- Nest in stumps, logs, railroad ties
- Often nest in moist wood in houses
Acrobat Ant (Camponotus pennsylvanicus)
- Get name from habit of raising abdomen over head when disturbed
- Black with yellow legs and thorax
- Common in western US
- Nest in logs, tree limbs, posts, lumber
Western Carpenter Ant (Camponotus modoc)
- Largest species
- Black overall with pale yellow markings on thorax
- Common in Pacific Coast states
- Nest in trees and damp wood
Florida Carpenter Ant (Camponotus floridanus)
- Very large, 15-20 mm
- Completely black coloration
- Most common in Florida but found in other Southeastern states
- Nest in dead trees and lumber
California Carpenter Ant (Camponotus modoc)
- Large ants at 10-15 mm long
- Dark brownish-black color
- Common in California and Mexico
- Nest in logs, stumps, and moist wood
Carpenter Ant Control
Carpenter ant infestations can be controlled through a combination of monitoring, improved sanitation, physical barriers, baits, dusts, and liquid insecticide sprays. Here are some tips:
- Find and seal possible entry points with caulk, weather stripping, etc.
- Trim back trees/branches touching the structure
- Keep firewood 20+ feet from home
- Fix any moisture problems like leaks, condensation, etc.
- Apply occasionally pyrethroid sprays around doors, windows, etc.
- Use boric acid dust in wall voids and attics as needed
- Baits containing boric acid placed along foraging trails
- Keep food cleaned up and sealed to reduce attraction
- Inspect for new tunnels and nests both indoors and out
For heavy infestations, fumigation by a professional pest control company may be required. Nest sites inside wood may need to be excavated and repaired.
Conclusion
Carpenter ants are large black or reddish ants that excavate wood to create galleries and tunnels for nesting. They can be identified by their large size, elbowed antennae, single node waist, and signs of wood damage including small holes and coarse sawdust. Carpenter ants do not consume wood like termites do. While carpenter ants primarily nest outdoors, they may create satellite nests indoors in exposed wood. Effective control involves improving sanitation, sealing entry points, applying targeted insecticides, and sometimes professional fumigation or excavation. Being able to identify carpenter ants is important for preventing structural damage and controlling infestations.