If you’re trying to figure out how to get rid of ants in your house, the first thing to know is this: nine times out of ten in the Bay Area, those little brown ants marching across your kitchen counter are Argentine ants — and the way most people try to kill them actually makes the problem worse.

Argentine ants don’t behave like the ants you grew up swatting in other parts of the country. They form supercolonies that can stretch across entire neighborhoods, and a can of spray from the hardware store can literally split one colony into several. This guide walks through what to do right now when you see a trail, what to stop doing, and how to keep them from coming back — informed by what Banner technicians see every day across the Bay Area, from Sonoma down to Gilroy.

Short Answer

To get rid of ants in your house, resist the urge to spray the trail. Instead, identify the entry point, clean the pheromone trail with soapy water, use slow-acting ant bait the workers will carry back to the colony, and then seal entry points and eliminate moisture and food sources. In the Bay Area, you’re almost certainly dealing with Argentine ants, and killing the visible ants on contact only triggers the colony to split and forage harder.

How do you get rid of ants in your house?

The fastest way to get rid of ants in your house is to let the ants do the work for you — place a slow-acting sugar-based ant bait directly in the trail and leave it alone for several days so workers carry the poison back to the queen. At the same time, wipe down surfaces with soapy water or vinegar to erase the pheromone trail, and seal the crack, gap, or utility penetration they’re using to get in. Contact sprays feel satisfying but break Argentine ant supercolonies into multiple smaller colonies, which is why so many Bay Area homeowners feel like their ant problem keeps getting worse the more they fight it.

Why You’re Probably Dealing With Argentine Ants

If you live anywhere from San Rafael to San Jose, the ants in your kitchen are almost certainly Argentine ants. They’re small, uniformly brown, and move in tight trails along baseboards, countertops, and windowsills. They’re the single most common indoor pest call Banner gets, and they dominate pest activity across Marin, the Peninsula, the East Bay, and the South Bay.

Here’s what makes them different from the ants most people are used to:

• They form supercolonies. Instead of one queen and one nest, Argentine ants have many queens spread across interconnected colonies that can span blocks. Your neighbor’s yard and your yard may be part of the same colony.
• They don’t fight each other. This is how the supercolony keeps expanding. There’s no territorial check on their numbers.
• They respond to stress by splitting. This is the critical part. When you hit a trail with a contact spray, surviving workers carry stress pheromones back, and the colony responds by budding — queens split off and start new satellite colonies. One ant problem becomes three.

This is why homeowners in places like Palo Alto, Walnut Creek, and Novato often describe the same frustrating pattern: they spray, the ants disappear for a few days, and then trails show up in two or three new rooms.

What to Do Right Now When You See a Trail

Found a trail of ants on your counter this morning? Here’s the practical sequence.

1. Don’t spray it. Put the Raid down.

2. Follow the trail to the entry point. Look for where the ants are coming from — a gap under a window, a crack where the counter meets the wall, around a dishwasher, along a baseboard, or through a utility penetration under the sink. Knowing the entry point matters more than killing what you see.

3. Wipe the trail with soapy water or a vinegar solution. Ants navigate by pheromone trails. Erasing the trail disorients the foragers and buys you time. Don’t use bleach — it’s unnecessary and the smell drives some homeowners crazy.

4. Place slow-acting ant bait in the path. Use a sugar-based liquid bait (Terro and similar products work for Argentine ants because they’re sugar-feeders, not protein-feeders most of the year). Place it near the entry point, not in the middle of the room. The workers need to find it, eat it, and carry it back.

5. Leave the bait alone. This is the part that’s hardest for people. You’ll see more ants at first — that’s the bait working. They’re recruiting nestmates to a new food source, which is exactly what you want. If you spray them off the bait, you’ve defeated the whole purpose.

6. Give it 3–7 days. Liquid sugar baits work slowly by design. Fast-kill baits don’t give workers time to feed the queens.

Why DIY Sprays Usually Make It Worse

The pest control aisle is full of products that promise to kill ants on contact. For most ant species, those products work fine. For Argentine ants — the species you almost certainly have — they’re counterproductive.

Here’s what happens when you spray a trail:

• The visible workers die immediately
• A chemical barrier remains on the surface
• Surviving ants detect the dead nestmates and the chemical stress signal
• The colony responds by budding — producing new queens and splitting into satellite colonies
• Those satellite colonies find new entry points into your home

This is why so many Bay Area homeowners feel like they’ve been battling ants for years with no progress. The product they’re using is actually fueling the expansion.

The rule: bait, don’t spray. If you must use a product beyond bait, use it outside at the foundation line, not on indoor trails.

Long-Term: How to Stop Ants From Coming Into Your House

Killing the colony in your kitchen is step one. Keeping the next colony out is step two — and it’s more important, because your house is sitting inside a supercolony that extends across the neighborhood. The conditions that attracted one colony will attract another.

Eliminate moisture

Argentine ants come indoors chasing water more often than food, especially during the dry season. In the Tri-Valley — Walnut Creek, San Ramon, Pleasanton, Livermore — summer indoor ant pressure spikes dramatically because it hasn’t rained in months and the landscape is bone dry. Your dog’s water bowl, a leaky sink trap, or condensation behind the fridge becomes the most attractive water source for blocks.

• Fix slow leaks under sinks and around dishwashers
• Wipe standing water off countertops at night
• Check that bathroom exhaust fans are actually venting
• Clear condensation from window tracks

Eliminate food sources

You’re never going to eliminate every crumb, but the high-value targets are:

• Sticky spots on counters and floors (juice, syrup, honey)
• Pet food left out overnight
• Open sugar, honey, or fruit on counters
• Fruit bowls (especially overripe fruit)
• Recycling bins with residue in cans and bottles

Seal entry points

This is where most homeowners underinvest. Ants are tiny. A gap the width of a credit card is a highway. Walk the perimeter of your kitchen and bathroom and seal:

• Gaps where countertops meet walls
• Cracks around window frames
• Utility penetrations under sinks (where pipes enter the wall)
• Gaps at the base of exterior doors
• Cracks in grout or tile

A full walkthrough of how to prevent pests in your home covers the exclusion work in more detail.

Manage the exterior

Ants live outside. They only come in when something draws them in. On the outside of the house:

• Keep mulch, wood chips, and landscape debris pulled back 12+ inches from the foundation
• Trim shrubs and tree branches so they don’t touch the siding (this is a literal highway into the house)
• Clean up ripe fruit under trees
• Address aphid problems on landscape plants — aphids produce honeydew, and Argentine ants farm aphids for it, which is why ant pressure often correlates with healthy gardens

Bay Area Microclimates and Ant Pressure

Where you live in the Bay Area affects how bad ant pressure gets and when it peaks.

Marin and the North Peninsula (San Rafael, Novato, Mill Valley, Menlo Park) see heavy year-round Argentine ant pressure because of mild temperatures and mature landscaping. Indoor trails show up in January just as easily as July.

South Bay inland (San Jose, Milpitas, Morgan Hill, Gilroy) gets intense summer and early-fall pressure. The long dry season drives ants indoors looking for water. Agricultural edges around Gilroy and Morgan Hill keep colony numbers high.

Tri-Valley and outer East Bay (Walnut Creek, Concord, San Ramon, Livermore) sees the classic summer spike — hot dry afternoons push ants indoors aggressively starting in June and peaking in August.

Urban core (San Francisco, Oakland, Berkeley) has heavy Argentine ant pressure in older homes and ground-floor units, compounded by the general density of foraging trails across blocks.

North Bay wine country (Santa Rosa, Sebastopol, Petaluma, Healdsburg) gets strong ant pressure in homes backing up to vineyards, pastures, or open space. Fall rains can push ants indoors suddenly.

Coastal fog belt (Half Moon Bay, western San Francisco) sees somewhat lower Argentine ant indoor pressure but more moisture-loving pests overall.

Signs Your DIY Approach Isn’t Working

If any of the following are true, the colony has probably already budded and you’re fighting multiple satellite colonies:

• Trails disappear from one spot and reappear in a different room within days
• You now have ants in rooms you didn’t have them in before
• Bait seems to work briefly but trails return within a week or two
• You’re finding ants in multiple floors of the house
• You’ve been treating the same issue for more than a month with no lasting result

At that point, the question shifts from “what product do I buy next” to whether it’s time to bring in a professional. Is pest control worth it? breaks down that decision honestly.

What Professional Treatment Actually Does Differently

Three things make professional ant treatment more effective than DIY for Argentine ants:

1. Non-repellent products. Professionals use non-repellent treatments on the exterior that ants walk through without detecting. They carry the product back to the colony and transfer it through the supercolony. No stress-bud response.
2. Exterior-first strategy. Treating the perimeter of the house addresses the pressure at its source, not just the visible trails inside.
3. Consistency. Argentine ant pressure is constant in the Bay Area. A one-time treatment knocks the colony down; quarterly service keeps the exterior protected through the seasonal shifts that drive them indoors — spring foraging, summer water-stress, and fall migration.

Banner’s approach for active ant problems is a targeted initial service to resolve the infestation, followed by a quarterly pest control schedule to keep the exterior under control. Not monthly. Quarterly works for Argentine ants because of how the products and colony biology interact.

For a full breakdown of what ongoing service runs in the Bay Area, see the real cost of quarterly pest control.

Bottom Line

Figuring out how to get rid of ants in your house comes down to two things: stop doing the things that make Argentine ant colonies split, and start doing the things that remove the reasons they came inside in the first place. Bait instead of spraying. Seal entry points. Eliminate moisture and food sources. Manage the exterior. And accept that because you’re living inside a supercolony that covers your whole neighborhood, consistency matters more than any single treatment.

If you’ve been fighting the same ant problem for months and it keeps coming back, or the trails are showing up in new rooms every few weeks, that’s the signal DIY has hit its ceiling. The next step is simple: call Banner and book an inspection. A local technician who knows your microclimate will walk your property, identify the entry points and conditions driving the infestation, and recommend a plan built around your specific home. No upsell. No pressure.