Carpenter Ants

Carpenter ants are large ants, usually black or red-and-black and 1/4 to 1/2 inch long, that nest inside wood by chewing out smooth galleries. They don't eat wood, but a colony living in damp framing, window sills or a porch can weaken it over years, so carpenter ants in the house are worth taking seriously.

The common species in the North and East is the black carpenter ant (Camponotus pennsylvanicus); the West has several red-and-black species; Florida has its own orange-and-black carpenter ants.

What carpenter ants look like

• Size: workers 1/4–1/2 inch, varying within one colony (major and minor workers); queens up to about 5/8 inch.
• Color: jet black in the East; black with a reddish thorax in many Western species; orange-brown and black in Florida.
• Profile: an evenly rounded, arched thorax, a single node at the waist, and no stinger.
• Antennae: elbowed, 12 segments.
• Behavior: workers forage singly or in loose lines, mostly from dusk to dawn, and travel along wires, pipes, gutters and branches touching the house.

How to identify carpenter ants vs black ants

More look-alikes in our types of ants guide.

Winged carpenter ants (flying carpenter ants)

Do carpenter ants have wings? Workers don't; reproductive males and queens do. Mature colonies (usually 3–6 years old and several thousand workers) release swarmers in spring and early summer. Winged queens are the largest ants you'll likely see in a house.

If winged carpenter ants appear indoors in late winter or early spring, the colony is probably inside the structure, because outdoor colonies swarm outside. A few swarmers in summer near an open door are less concerning.

Winged ants vs termites: ants have a pinched waist, elbowed antennae and front wings longer than hind wings; termite swarmers have a thick waist, straight antennae and four equal wings. See termites vs ants.

Do carpenter ants bite?

Yes. Carpenter ants bite in defense, and with large mandibles the pinch is sharp. Some species spray formic acid into the bite, adding a short burning sensation. There's no stinger and no dangerous venom; wash the spot and use a cold pack. See ant bites.

What carpenter ants eat

Carpenter ants are omnivores: honeydew from aphids and scale insects on trees is their main food, plus living and dead insects, fruit juices and, indoors, sugar, syrup, meat, grease and pet food. They expel wood shavings from the nest instead of digesting them, which is why you find frass piles.

Where carpenter ants live

Outdoors: dead trees, stumps, logs, landscape timbers, firewood piles. Indoors they prefer wood that is or was wet:

• Window and door frames, sills
• Around leaky roofs, chimneys, skylights and gutters
• Under bathtubs, showers and dishwashers
• Porch and deck framing, sill plates over damp crawlspaces
• Hollow doors, wall voids, foam board insulation

A large parent colony often lives outside (in a tree or stump) with satellite nests in the house connected by trails. That's why killing indoor ants alone often fails.

Signs of carpenter ants in your house

• Large ants indoors in late winter or early spring
• Winged ants emerging from walls, ceilings or window frames
• Frass: coarse, fibrous shavings mixed with insect parts below small slits in wood
• Faint rustling or crinkling sounds in walls at night
• Smooth, sandpaper-clean galleries in damaged wood (termite galleries are rough and packed with mud)

Detailed checklist: signs of carpenter ants.

Florida carpenter ants

Florida has two common species: the Florida carpenter ant (Camponotus floridanus), orange-red head and thorax with a black abdomen, and the tawny carpenter ant. Florida carpenter ants nest in palm boots, landscape timbers, attics and wall voids, often in dry wood, and readily bite when disturbed. They're a frequent call for Florida pest control companies, especially after they move indoors during heavy rain.

Are carpenter ants dangerous to a house?

Less than termites, but not harmless. Damage builds over years and almost always where wood has been wet. Penn State and UC IPM both stress that the long-term fix is the moisture problem. A long homeowner thread on Hearth.com shows the usual pattern: people heard chewing in walls, found sawdust and hollowed posts, tried sprays, dusts and bait stations, and often saw fresh frass again at spring thaw until the nest itself was reached.

Carpenter ants are often confused with carpenter bees, which drill perfectly round 1/2-inch holes in bare wood. Different insect, different fix.

What to do

1. Confirm the ID (size, single node, arched thorax).
2. Track foragers at night with a red-filtered flashlight to find where they enter and where they go.
3. Look for moisture problems and frass near the suspected nest.
4. Bait plus nest treatment; see how to get rid of carpenter ants.

Call a pro if the nest is inside walls you can't open, if damage is visible, or if baiting fails after 3–4 weeks. Carpenter ant treatment typically costs roughly $250–$600 in the US (approximate), more if repeat visits or wood repair are needed.