Ants in the winter?

Ever wonder what’s going on when you find ant activity in the dead of the winter? It’s usually a sure sign that you’ve got a nest somewhere in your home!

Every year around January and February we get a rash of calls from homeowners across central NY about ant activity in their homes. Of course no one likes to see uninvited six legged house guests in their bathrooms or kitchens, but when you see these little workers foraging in your home in the winter, you know you’ve got a problem.

Two species of ants account for the lions share of wintertime ant sightings, the black Carpenter Ant (camponotus Pensylvanicus) and the Pavement Ant (Tetramorium caespitum).

Big Black Ants

When you find “big black ants” in the home in the winter, you’ve got Carpenter Ants. Their presence is an indication that a nest has been established within the home. Even in the deepest coldest months of the upstate NY winter, enough warmth can stir the workers in one of these nests to activity. Often these winter time nest locations can be within south or west facing walls, window and door frames, or even up in eaves and attic crawlspaces. Because Carpenter Ants are so adaptable, almost no part of a home that has the right environmental conditions, is safe from the potential nesting activity of carpenter ants. In the winter however, the nest location is almost always in an area of the home that either receives plenty of sun or is warmed by the homes heating system.

Don’t fret however, you may just have a satellite colony! Carpenter Ants are known to maintain several satellite colonies for each brood nest. A brood nest is where the queen lives and the initial stages of reproduction take place. A satellite colony may have the later stages of development, most notably pupa, and a number of workers to maintain the colony. Satellite colonies are typically smaller than brood nests, though they may also destroy timber elements of your home. Satellite colonies can be established MUCH quicker (in as little as a week in some cases) and are most often the nest type that we find responsible for wintertime activity. I suspect (based on years of observation and no independent research!) that many of these satellite colonies are established in the fall to allow next spring’s reproductives (winged ants) to pupate. I base this on the fact that we often find winged reproductives in the very early spring in these nest sites, often right after the snow has melted. It is unlikely that these highly immobile (while crawling) winged ants entered the structure in the spring, therefor they must have been brought in by workers in the fall.

“What about the tiny brown ants?”

The other common winter ant invader is the Pavement Ant. These tiny red-ish brown to black colored ants are often found around kitchens and bathrooms. It goes by many common names like sugar ants, grease ants, and various other more unsavory names we won’t repeat in sorted company! Unlike Carpenter Ants, Pavement Ants are soil nesting ants. They are not destructive to structural elements of the home but can present a major nuisance to the structures occupants. Being a soil nesting insect, we often begin searching for wintertime nest locations where foundation slab or basement floor areas remain warm all winter long. In commercial buildings these ants often nest where water and drain or utility lines penetrate the slab foundation.

Control of Pavement Ants during the winter can present some interesting challenges. Due to their preferred nesting locations, a direct pesticide application can be somewhere between difficult and impossible. few homeowners appreciate drilling into a concrete floor to treat an ant colony! The most common application technique for Pavement Ants is a baiting program. They are readily controlled by gel and granular formulated baits during the spring, summer and fall. The problem with wintertime bait programs is that a very small percentage of the workers are ever active. This means that very little bait will ever make it to the colony. It is conceivable that the bait looses it’s effectiveness (because it dries out or becomes less competitive against other food sources) before enough ants become active with their springtime foraging duties. This means that often, treatments for pavement ants made in the winter require follow-up applications in the spring when the rest of the colony becomes active.

If you are seeing ants anytime when we have snow on the ground, its a good idea to call a professional for an inspection and service recommendations.


About Andy Sanefski

Owner - Perimetek Pest Management Expertise in structural pest management and food safety
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