Ant Control in Westchester County: Pavement Ants, Odorous House Ants & Carpenter Ants

Westchester's Ant Problem: Three Species, Three Solutions

Every spring, as temperatures climb through April and May, one of the most common calls Hello Pest Control receives is about ants. But not all ant problems are the same. Westchester County is home to three primary ant species that invade homes and damage property, and each one requires a different identification, a different treatment strategy, and a different understanding of where the real problem is hiding. Getting the treatment right means getting the identification right first.

Here's what's likely crawling through your Westchester home — and what to do about it.

Pavement Ants: Southern Westchester's Driveway Invaders

If you live in Yonkers, Mount Vernon, or New Rochelle and you're finding tiny dark ants trailing across your kitchen floor in spring, you're almost certainly dealing with pavement ants (Tetramorium caespitum).

Pavement ants are small — about 1/8 inch long — and dark brown to black. As their name suggests, they build their nests beneath concrete slabs, driveways, patios, sidewalks, and the foundation walls of homes. In dense, more urbanized southern Westchester neighborhoods where lots are smaller and impervious surface coverage is high, pavement ants thrive.

In early spring, colonies expand and workers forage aggressively into kitchens seeking sugar, grease, and protein. You may also notice small piles of displaced soil appearing between the cracks of your driveway or at the base of your foundation — those are excavated from the nests below.

Treatment: Pavement ants respond well to a combination of gel bait — placed along foraging trails where workers will carry it back to the queen — and exterior perimeter spray targeting nesting sites at the foundation and under slab edges. Professional treatment is far more effective than hardware store sprays, which kill visible foragers but leave the colony intact to send more workers.

Odorous House Ants: The Coconut-Smelling Culprit

Throughout Westchester's suburbs — White Plains, Scarsdale, Harrison, Ardsley, Elmsford — one of the most frequent ant complaints involves small brown ants that seem to be everywhere at once and that, when crushed, produce a distinctive smell that most people describe as rotten coconut. These are odorous house ants (Tapinoma sessile), named for precisely that characteristic.

Odorous house ants are opportunistic nesters. Unlike pavement ants, they're comfortable establishing colonies inside wall voids, under kitchen cabinets, inside insulation, and near moisture sources — leaking pipes, dishwashers, under sinks. They follow moisture trails and are heavily attracted to sweet foods and sugary liquids.

What makes odorous house ants particularly frustrating is their colony structure. A single colony may contain multiple queens and dozens of satellite nests throughout a structure. Disturbing a colony — including spraying it with over-the-counter repellent sprays — can trigger budding, where queens and workers break off to form new colonies elsewhere in the home. This is called colony fragmentation, and it's why DIY spraying often makes infestations worse.

Treatment: The key is treating the trail and the nest, not just the visible ants. A professional will use slow-acting gel bait that workers carry back to the queen, combined with non-repellent residual spray that disrupts the colony without triggering fragmentation. Identifying and eliminating moisture sources is equally important to prevent re-colonization.

Carpenter Ants: Northern Westchester's Structural Threat

The most serious ant pest in Westchester County — and the one that causes property damage — is the carpenter ant (Camponotus pennsylvanicus). These are the largest ants in the northeastern United States: workers range from 1/4 to 3/4 inch long, and they are black, or black with reddish-brown coloring.

In northern Westchester — Bedford, Katonah, Pound Ridge, Yorktown, North Salem — older homes with mature trees and higher moisture levels create ideal conditions for carpenter ant infestations. Carpenter ants don't eat wood; they excavate it to create galleries for nesting. They're strongly attracted to wood that has been softened by moisture: deck ledger boards, window sills, sill plates near the foundation, attic beams near roof leaks, and hollow trees or stumps in close proximity to the home.

The first sign of a carpenter ant problem is often frass — a coarse, sawdust-like material mixed with insect body parts — found on the floor below a wall, near a window frame, or in a basement or crawl space. You may also hear faint rustling inside walls at night. By the time you notice visible structural damage, the infestation is typically well established.

Left untreated over years, carpenter ants can cause significant structural damage. Unlike termites, they don't consume wood, but the galleries they create compromise the integrity of structural members in the same way — and infested wood is then more vulnerable to water damage and decay.

Treatment: A thorough carpenter ant treatment begins with a professional inspection to locate the primary nest and any satellite nests. Treatment typically involves direct void injection of residual insecticide into confirmed gallery areas, exterior perimeter treatment to intercept foraging workers, and bait application along established trails. Structural and moisture issues identified during the inspection should be addressed to prevent re-infestation.

Why DIY Fails for All Three Species

The most common reason ant problems persist in Westchester homes is misidentification and the use of repellent sprays. Hardware store sprays containing pyrethrins or pyrethroids are contact killers — they kill the ants they touch but actively repel the rest of the colony, which retreats and reroutes around the treated area. With odorous house ants, repellent sprays can cause colony fragmentation. With carpenter ants, surface sprays don't reach the galleries. With pavement ants nesting under slabs, surface treatment simply doesn't get deep enough.

Professional treatment uses the right product for the right species: slow-acting non-repellent baits that the colony unknowingly distributes to the queen; targeted void injection for carpenter ants; and perimeter treatment timed to the foraging cycle.

Pricing and Timing

Ant treatment for pavement ants and odorous house ants is typically $300–$450 for an initial treatment. Carpenter ant treatment, which may include a more detailed structural inspection, is similarly priced but may involve follow-up visits if satellite nests are extensive.

Spring — April through June — is peak ant activity season in Westchester. Colonies are expanding, queens are laying eggs, and foraging pressure is at its highest. This is the ideal window to treat: colonies are actively accepting bait, workers are visible and trackable, and getting ahead of the infestation now prevents a much larger problem by midsummer.

Hello Pest Control serves Yonkers, Mount Vernon, New Rochelle, White Plains, Scarsdale, Harrison, Bedford, Katonah, and Pound Ridge, along with all of Westchester County. If you're seeing ants this spring, don't wait for the problem to grow. Call Hello Pest Control at (888) 973-7839 for a professional ant inspection and same-season treatment.