It starts with one or two ants on the kitchen counter. Then a line along the backsplash. Then they’re in the cabinets, under the sink, around the dog bowl. Welcome to ant season in St. Louis.

Ants are the most common pest complaint we receive from March through October and for good reason. The St. Louis area is home to several ant species that actively invade homes every spring. Understanding which ants you’re dealing with and why they showed up is the first step to getting rid of them for good.

Why Ants Invade in Spring 🐜

Ant colonies are driven by temperature. When soil temperatures rise above 50°F, which happens in the St. Louis area around late February to early March colonies become active and send out scout ants to locate food and water sources.

Those one or two ants on your counter aren’t random. They’re scouts. If they find food, they leave a pheromone trail that leads the rest of the colony straight to the source. Within days, a casual scout visit becomes a full invasion trail.

Here’s the timeline we see every year in St. Louis:

‣ March: Scout ants appear — a few at a time, usually in kitchens and bathrooms

‣ April: Full foraging trails establish along counters, baseboards, and under sinks

‣ May – June: Colonies are at peak size and trails are well-established. Much harder to eliminate.

Common Ant Species in the St. Louis Area

Odorous House Ants

The most common kitchen invader in Missouri. Small (1/16 to 1/8 inch), dark brown to black, and they emit a distinct rotten-coconut smell when crushed. They nest in walls, under floors, and in the soil near foundations. They’re after sweets and moisture.

Pavement Ants

Small, brown ants that nest in cracks in driveways, sidewalks, and along foundations. You’ll see small mounds of fine dirt pushed up through cracks. They forage indoors for greasy and sweet foods and are especially common in basements and ground-level rooms.

Carpenter Ants

This is the one to worry about. Carpenter ants are large (1/4 to 1/2 inch), typically black, and they tunnel through moist or damaged wood to build their nests. Unlike termites, they don’t eat wood — they excavate it. But the structural damage they cause is real.²

Warning signs of carpenter ants:

‣ Frass: Smooth, sawdust-like shavings piling up near baseboards or windowsills

‣ Faint rustling sounds inside walls, especially at night

‣ Large black ants seen near moisture sources — sinks, bathtubs, leaky windows

‣ Winged ants emerging indoors means a mature colony is in the structure

Why DIY Ant Treatments Don’t Work

We hear this every week: “I’ve been spraying, but they keep coming back.” Here’s why:

👉 Killing Scouts Doesn’t Kill the Colony

The ants on your counter are a tiny fraction of the colony. The nest which can contain thousands to hundreds of thousands of workers is somewhere else entirely: in the walls, under the foundation, or in the yard. Killing the scouts just prompts the colony to send more.

👉 Spray Repellents Scatter the Problem

Most store-bought ant sprays are repellents. They create a chemical barrier that ants avoid which sounds good, but actually causes the colony to split and establish new trails in different areas of your home. One ant problem becomes three.

👉 Home Remedies Disrupt Trails Temporarily

Vinegar, cinnamon and peppermint oil they may disrupt the pheromone trail for a few hours. But the colony is still there, and it will find a new route. These are temporary disruptions, not solutions.

How Professional Ant Treatment Works

Professional treatment targets the colony, not just the ants you see. Here’s how:

✅ Spray Repellents Scatter the Problem

We identify the species (this determines the treatment approach), locate entry points, and trace trails back toward the nest. Different ant species require different strategies.

✅ Baiting

Commercial-grade gel and granular baits are placed along foraging trails and near entry points. Scout ants carry the bait back to the colony, where it spreads through the population and reaches the queen. This is how you eliminate the source.

✅ Exterior Treatment

Targeted treatment along the foundation, siding channels, and entry points creates a barrier that stops new invasions. We also treat areas where nests commonly occur — mulch beds, landscape timbers, and cracks in driveways.

✅ Follow-Up

Most ant treatments show significant results within 1–2 weeks. Follow-up visits ensure the colony is eliminated and not just temporarily disrupted.

Our technicians are trained to identify ant species on sight and target treatment to the colony, not just the ants you see.

Prevention: How to Keep Ants Out

Once the immediate problem is treated, these habits keep ants from coming back:

In the Kitchen
1. Wipe counters every night — even small crumbs attract scouts
2. Store food in sealed containers — especially sugar, honey, cereal, and pet food
3. Fix dripping faucets — ants need water as much as food
4. Clean behind the stove and fridge — crumbs and grease accumulate in these hidden areas
5. Take trash out daily and use a can with a tight-fitting lid

Around the House
1. Seal cracks and gaps where pipes enter walls, around windows, and along the foundation
2. Pull mulch back at least 12 inches from the foundation
3. Trim vegetation that touches the house — branches and shrubs are ant highways
4. Fix moisture issues — leaky faucets, poor drainage, condensation
5. Store firewood away from the home and elevated off the ground