Carpenter Ants: How to Recognize the Signs of an Infestation

Q: What does a carpenter ant nest look like?

You usually cannot see it. Florida carpenter ants nest inside voids: wall cavities, window and door frames, attic insulation near the eaves, hollow patio supports, palm leaf bases and rotting stumps. What you see is the evidence outside the void, such as a trail of large ants at night, winged ants or a small pile of debris below a crack or gap.

Q: Are carpenter ants worse than termites?

For South Florida homes, usually not. Termites eat wood, while Florida carpenter ants only nest in voids and in wood that is already soft from moisture or decay. A carpenter ant colony is still a warning that something is wet or rotting. Termites, on the other hand, can do serious structural damage, so have any winged insects identified. Our termite guide explains the differences in damage.

Q: Is one big ant in the house a sign of an infestation?

Not necessarily. A single forager can wander in from a tree or shrub touching the house. Watch for a pattern: several large ants on most nights, ants following the same route along a baseboard, wire or window frame, or winged ants indoors. Those signs suggest a nest inside or right next to the structure and are worth an inspection.

Q: Do carpenter ants come out during the day?

Some do, but most activity is at night. UF/IFAS reports that Florida carpenter ant foraging peaks from just before sunset until about two hours after sunset, with another peak around dawn. That is why many families only notice them when they turn on the kitchen light late in the evening. A flashlight check after dark is the easiest way to find the trail.

Key takeaways

The most common sign in South Florida is large, two-toned ants walking through the kitchen or bathroom after dark.
Florida carpenter ants forage mostly from just before sunset to about two hours after, with another peak around dawn (UF/IFAS).
Small piles of debris called frass, pushed out of a nest, often sit below wall voids, window frames or soft wood.
Florida carpenter ants do not excavate sound wood, so a nest usually points to a void, a leak or wood already softened by moisture.
Winged carpenter ants indoors, mostly in the rainy season, mean a mature colony is close by and should be identified, not just sprayed.

In this article

Which Carpenter Ants Live in South Florida Homes?
Sign 1: Large Ants Indoors After Dark
Sign 2: Winged Ants Near Windows and Sliding Doors
Sign 3: Frass Below Voids and Gaps
Sign 4: Trails Along Wires, Branches and Cables
Sign 5: Soft or Damaged Wood Near a Leak
How to Tell Carpenter Ant Signs From Look-Alikes
What to Do When You Find the Signs
How a Professional Confirms and Treats Carpenter Ants
Frequently Asked Questions

The clearest signs of a carpenter ant infestation are large ants trailing through your home at night, winged ants near windows and sliding doors, and small piles of debris pushed out of a wall, window frame or other hidden space. In South Florida, those ants are almost always Florida carpenter ants, and where they nest tells you as much about your house as it does about the ants.

Many guides describe carpenter ants as wood borers that leave long tunnels and piles of sawdust. That picture comes from the northern black carpenter ant. The species in Miami-Dade, Broward, Palm Beach and the Keys behaves differently, so the signs you should look for are different too. This guide walks through each one, how to tell it apart from look-alikes, and what to do once you find it.

Sawdust-like frass below a wooden window frame, a telltale sign of carpenter ants.

Which Carpenter Ants Live in South Florida Homes?

The main carpenter ant in South Florida houses is the Florida carpenter ant, Camponotus floridanus, often called the “bull ant.” According to UF/IFAS, workers are 5.5 to 11 mm long (about 1/4 to 1/2 inch), with an ash-brown to rusty-orange head and thorax, a black abdomen and long golden hairs. In a survey of four Florida metro areas, Florida carpenter ants accounted for about 20% of homeowner ant complaints.

Two relatives show up too:

Tortugas carpenter ant (C. tortuganus). A thinner, paler relative of the Florida carpenter ant found in central and southern Florida.
Compact carpenter ant (C. planatus). A smaller, more compact relative that lives mainly in trees. UF/IFAS notes it is the subject of numerous calls to pest control operators in South Florida and is increasingly recognized as a structural pest.

All of them bite rather than sting, and the Florida carpenter ant can spray formic acid when it defends itself. For the full picture of how colonies grow, read carpenter ants: lifecycle, habitat and habits.

Sign 1: Large Ants Indoors After Dark

The most common sign is simply seeing big ants inside, usually in the kitchen, bathroom or near a window, and usually at night. UF/IFAS reports that Florida carpenter ants forage mainly from just before sunset until about two hours after sunset, with a second peak around dawn.

Pay attention to the pattern, not one ant:

Several large, two-toned ants on most evenings
Ants that appear in the same room or along the same baseboard each time
Ants walking toward sweets, pet food, fruit or a damp sink cabinet
Workers of different sizes, from medium to very large, in the same trail

A single ant can wander in from a tree. A nightly trail usually means the nest is inside the structure or right against it.

Need help with pests in South Florida?

Toro Pest Management has protected homes and businesses since 1969. Get a free inspection and $25 off your first service, backed by our 110% Satisfaction Guarantee: if the pests come back, so do we, at no extra cost.

Schedule My Free Inspection Call 305-594-4767

Sign 2: Winged Ants Near Windows and Sliding Doors

Winged carpenter ants are males and future queens leaving a mature colony to start new ones. UF/IFAS notes that winged Florida carpenter ants fly in the evening or at night during the rainy season, May through November, and that homeowner complaints peak during the spring swarm, usually between April and June. Indoors, UF/IFAS reports, they are most often found on window ledges and near sliding glass doors.

Winged ants inside, especially several on different days, suggest the colony is in your walls, attic or a window frame rather than in the yard. Winged ants are also easy to confuse with termite swarmers, and the two problems call for very different treatments. Save a few in a sealed bag and compare them with our guide to termites vs. flying ants.

Toro tip: Put a few winged insects in a zip-top bag or a piece of clear tape and keep them for your technician. A quick identification tells you whether you need ant control, termite control or simply better screens.

Sign 3: Frass Below Voids and Gaps

When carpenter ants clean out a nest, they push the waste outside. UF/IFAS calls these bits of debris frass. It consists of bits of excavated material mixed with pieces of dead insects, including carpenter ants.

Look for small piles of this debris:

Under window and door frames, especially on the inside sill
Below cracks in drywall, baseboards and ceiling corners
In closets and under appliances, especially the dishwasher
Under hollow patio screen supports and patio ceilings
In the attic, near the eaves

Frass is different from termite evidence. Drywood termites leave hard, uniform droppings, and subterranean termites leave mud. Carpenter ant frass looks shredded and mixed, and finding insect parts in it is a strong clue.

Sign 4: Trails Along Wires, Branches and Cables

Carpenter ants travel. UF/IFAS describes trails running along wires and cables attached to homes, and notes that trees and shrubs touching the house act as bridges into attics and the upper parts of a house. Take a flashlight outside about an hour after sunset and look at:

Tree and shrub branches touching the roof, walls or screen enclosure
Cable, phone and power lines running from trees or poles to the house
The edges of soffits, fascia and roof vents
Hollow aluminum supports of screen enclosures

Following a few foragers back along their route often reveals the entry point and sometimes the nest itself. UF/IFAS also lists electrical, fuse and timer boxes among indoor nest sites, which is one reason ants sometimes appear in electrical outlets.

Sign 5: Soft or Damaged Wood Near a Leak

Here the South Florida story differs most from what you may have read. UF/IFAS states that Florida carpenter ants will not excavate nesting galleries in sound wood. They move into existing voids and hollow out only soft materials, such as rotten or pithy wood and Styrofoam.

So when you find carpenter ants in wood, the real question is why that wood is soft. Common culprits:

Window and door frames with moisture intrusion
Wall voids with moisture seepage, often near bathrooms
Flat roofs and skylights that leak
Wood already damaged by moisture or by old drywood termite galleries
The area under bathtubs and dishwashers

Treating the ants without fixing the leak leaves a perfect nest site for the next colony.

How to Tell Carpenter Ant Signs From Look-Alikes

Several other South Florida pests leave evidence that can be mistaken for carpenter ants.

What you see	Florida carpenter ant	Look-alike	How to tell
Large ants indoors	5.5-11 mm, two-toned, active at night	Most other house ants here are much smaller	Size and nighttime activity point to carpenter ants
Winged insects	Pinched waist, elbowed antennae	Termite swarmers	Termites have a thick waist and straight antennae
Debris piles	Shredded fibers mixed with insect parts	Drywood termite pellets	Termite pellets are hard, uniform and pile up below wood
Tubes on walls or trunks	Not built by carpenter ants	Bigheaded ant foraging tubes or termite mud tubes	Bigheaded ant tubes are fragile and crumble easily
Soil piles along walkways	Not typical	Bigheaded ants	Piles of loose, sandy soil along edges and pavers

The bigheaded ant is worth knowing. UF/IFAS notes that it builds debris-covered foraging tubes that resemble termite tubes, although they are much more fragile, and leaves piles of loose sandy soil. It does not nest in wood at all. For other invasive species around South Florida homes, see Florida’s most aggressive ant species.

What to Do When You Find the Signs

Once you see a pattern, act calmly and avoid making the problem harder to solve.

Do not spray everything. UF/IFAS warns that excessive treatment can become repellent and cause the nest to move to another location, and that finding the nest is the key to ant control.
Note when and where you see ants. Times, rooms and routes help find the nest.
Save winged insects for identification.
Check for moisture. Look under sinks and the dishwasher, around windows and in the attic near the eaves.
Trim branches that touch the roof or walls, and seal gaps around pipes, wires and cables.
Store sweets and pet food in sealed containers.

Our step-by-step guide on how to prevent a carpenter ant infestation covers the full prevention checklist.

Safety note: Do not spray liquids or pour chemicals into electrical outlets, switch boxes or breaker panels where ants appear. Turn to a licensed professional for treatments near electrical equipment and inside wall voids, and always follow product labels.

How a Professional Confirms and Treats Carpenter Ants

The hardest part of carpenter ant control is finding the nest, because it is usually hidden in a wall, a window frame, the attic or a palm next to the house. UF/IFAS recommends following foraging trails during the nighttime peak to locate it and notes that a small amount of product applied directly to the nest area is usually successful. Baits placed along the trail are another option, although carpenter ants are finicky feeders that do not always take them.

Toro’s technicians inspect inside and outside your home, follow the trails to the nests, confirm the species and treat nests, trails and entry points with products chosen for that ant and applied according to their label directions. You also get recommendations, such as trimming branches and fixing moisture problems, plus follow-up visits. Ongoing protection is available through Toro’s residential pest control plan, Total Home Protection Gold 365, an every-other-month service inside and outside your home.

Toro has protected South Florida homes since 1969, the first inspection is free, and if the bugs come back, so will Toro, at no additional cost to you. For more on the ants that share South Florida homes, browse our ant guide.

TORO Pest Management service truck parked outside the Miami office

Contact Toro today

A free inspection & $25 off your first service

A trained Toro technician inspects your home or business, explains what was found and gives you a clear plan and quote, backed by our 110% Satisfaction Guarantee.

305-594-4767

Schedule My Free Inspection Call Toro Now

Frequently Asked Questions

What does a carpenter ant nest look like?

You usually cannot see it. Florida carpenter ants nest inside voids: wall cavities, window and door frames, attic insulation near the eaves, hollow patio supports, palm leaf bases and rotting stumps. What you see is the evidence outside the void, such as a trail of large ants at night, winged ants or a small pile of debris below a crack or gap.

Are carpenter ants worse than termites?

For South Florida homes, usually not. Termites eat wood, while Florida carpenter ants only nest in voids and in wood that is already soft from moisture or decay. A carpenter ant colony is still a warning that something is wet or rotting. Termites, on the other hand, can do serious structural damage, so have any winged insects identified. Our termite guide explains the differences in damage.

Is one big ant in the house a sign of an infestation?

Not necessarily. A single forager can wander in from a tree or shrub touching the house. Watch for a pattern: several large ants on most nights, ants following the same route along a baseboard, wire or window frame, or winged ants indoors. Those signs suggest a nest inside or right next to the structure and are worth an inspection.

Do carpenter ants come out during the day?

Some do, but most activity is at night. UF/IFAS reports that Florida carpenter ant foraging peaks from just before sunset until about two hours after sunset, with another peak around dawn. That is why many families only notice them when they turn on the kitchen light late in the evening. A flashlight check after dark is the easiest way to find the trail.

Can I treat a carpenter ant nest myself?

Small, accessible nests can sometimes be treated with a labeled product, but most nests are inside walls. UF/IFAS warns that excessive treatment can become repellent and make the colony move to a new location, which spreads the problem. If you cannot reach the nest or ants keep returning, call a professional who can trace the trail and treat it according to the label.

Sources

Florida Carpenter Ant, Bull Ant, Tortugas Carpenter Ant, Camponotus floridanus (Buckley) and Camponotus tortuganus (Emery), UF/IFAS Extension
Compact Carpenter Ant (proposed common name), Camponotus planatus (Roger), UF/IFAS Extension
Bigheaded Ant, Pheidole megacephala (Fabricius), UF/IFAS Extension
Florida Carpenter Ants, UF/IFAS Extension
Ants, UF/IFAS Extension

Educational content. This article is for general information about pests in South Florida and is not medical, legal or professional advice. If you have a bite, sting or allergic reaction, contact your doctor; in an emergency, call 911. Pest problems vary from home to home, so a licensed professional should inspect before treatment. When using any pesticide, always read and follow the product label.