Ants Coming Out of the Fireplace

Two Very Different Problems

A handful of ants on the hearth the morning after you brought in a stack of logs is usually a nuisance that ends when the wood is burned. A trail of large ants that appears at dusk, week after week, from a gap beside the fireplace or out of the fire box, is a colony living somewhere in the chimney structure. The second is the one that matters, because of what it says about the wood around the chimney.

The woodpile can blur the line. UF/IFAS lists the inside of logs, stumps, old wooden fences and debris of almost any kind among outdoor nest sites, so a pile left sitting for months can hold a colony that you carry in one armful at a time. Keep firewood off the ground, away from the house and used within the season you bought it for.

What Florida Carpenter Ants Tell You

The Florida carpenter ant, also called the bull ant, is a frequent indoor insect pest in the state, according to UF/IFAS Featured Creatures. Workers are about 0.2 to 0.4 inches long, with a rusty-orange to brown head and thorax and a black abdomen covered in golden hairs. They bite but do not sting.

Unlike the black carpenter ant of the Panhandle and other regions, Florida carpenter ants do not tunnel into sound wood. UF/IFAS says they nest in existing voids or hollow out wood softened by moisture or fungi, and that they will not excavate galleries in sound wood. So when they settle in a structure, they are pointing at wet or damaged wood. Indoor nest sites the publication lists include wall voids with moisture seepage, areas under attic insulation near the eaves, and spots under windows and doors where rain gets in.

Where That Wet Wood Is Around a Chimney

A chimney is a common source of the moisture these ants need. The places to suspect:

• A framed chase: the wood box around a metal chimney pipe, wet from a rusted or leaking chase cover on top.
• Framing beside a masonry chimney where the flashing has failed and rain runs down the wood.
• The attic floor and eaves around the chimney, under wet insulation.
• Wood trim, mantel backing or the subfloor under the hearth where water has come down the flue.
• A woodpile or old stumps against the chimney base outside.

Telling Hitchhikers From a Nest

UF/IFAS describes Florida carpenter ants as night foragers, most active from just before sunset to about two hours after, and again around dawn, often wandering in loose trails. Use that to your advantage.

• Ants only near the log rack, gone a day or two after the wood is used: hitchhikers.
• Ants trailing at dusk from the same gap, night after night: a nest nearby.
• Piles of fine debris, called frass, of wood bits and insect parts below a gap: a nest being excavated.
• Winged ants at windows and sliding doors in spring: a mature colony in or near the house.

Checking the Chase Without Climbing

You can learn a lot about a wet chase from the ground and the attic. From the yard, look at the chase walls with binoculars for stains, bubbled paint or siding that has pulled away below the top. In the attic, with a flashlight, look at the wood around the chimney for dark staining, soft spots and wet insulation, and listen at dusk for faint rustling. Press a screwdriver gently into any stained wood; if it sinks in easily, the wood is soft.

Leave the roof alone. A chase top is high, often steep, and the cover up there is sharp-edged sheet metal. Looking at it is our job.

Ant or Termite?

Winged carpenter ants are often mistaken for termites, UF/IFAS notes, especially in the spring swarm season, usually April to June, when winged ants turn up along window ledges and near sliding doors. The differences are easy to see with a magnifier. Ant alates have elbowed antennae, front wings larger than the hind wings and a pinched waist. Termite alates have beaded antennae, front and hind wings of equal size and a broad waist. If yours are termites, see termites in fireplace.

Dealing With the Ants

The UF/IFAS advice is to find and treat the nest itself, applying a small amount of treatment directly to the nest area. Watch for trailing ants at their peak hours and follow them back; a few drops of sugar water or honey along the trail can draw more out and make the route clearer. Where the nest cannot be reached, use a bait made for carpenter ants and follow the label. Spraying near the nest but not on it can make the colony move.

The publication also recommends cutting the bridges they use: trim tree and shrub branches that touch the house, and note that wires and cables attached to the house serve as routes into attics. Caulking exterior openings and weather stripping help too.

Fixing the Water Behind Them

Killing the colony without fixing the wet wood leaves an empty nest site waiting for the next one. If the ants are in a framed chase or the wood around the chimney, the chase cover, the flashing or the crown is letting water in. That repair is ours, through chimney chase repair, and the ant treatment is a pest control company's.

The chase repair is where a family-owned, local crew like ours comes in. Based in Spring Hill and Proudly American, our experienced crew opens up wet chases and fixes failed flashing after a free inspection and a written estimate. Expect a Proudly American straight answer about which part is our job and which belongs to the pest service.

Sources

• UF/IFAS Featured Creatures: Florida carpenter ant: Florida carpenter ant: common indoor pest; size and coloring; bites, no sting; does not excavate sound wood, nests in voids or moisture/fungus-softened wood; frass; interior nest sites (wall voids with moisture, attic insulation near eaves, under windows and doors); night foraging hours; swarm season April to June; ant versus termite alates; follow trail, sugar water, baits, treat nest directly; bridges from trees and wires; caulking and weather stripping