Ants typically start coming into houses in late spring through early fall when the weather warms up. The most common months for ant invasions are May, June, July, August, and September. However, this can vary by region and species.
When Are Ants Most Active?
Ants become more active in warmer weather, which is why they tend to invade homes more during late spring, summer, and early fall. Here are some key factors that influence indoor ant activity:
- Warm temperatures – Most ant species prefer temperatures between 70-90°F. When the weather heats up, ants begin foraging more for food and water.
- Rainfall – Periods of heavy rainfall often drive ants indoors to seek shelter and avoid flooded nests.
- Established colonies – Ant colonies that have had time to grow and expand their numbers send out more foragers.
- Mating season – Some ant species invade structures while mating and establishing new nests.
- Food availability – Lack of food outdoors prompts ants to enter buildings in search of sustenance.
These conditions are most common in spring through early fall, drawing ants inside homes and businesses. Let’s look more closely at ant activity during these months.
May is often one of the first months when home and business owners start noticing increased ant invasions. Warming temperatures coupled with spring rainfall cause ants to begin foraging indoors for food and nesting sites. Common ant pests like odorous house ants, pavement ants, and Argentine ants all become more active in May. Carpenter ants may also start nesting indoors and foraging during this month.
Ant infestations tend to peak in June as daily high temperatures consistently reach 70-90°F, creating ideal foraging conditions for many ant species. Pharaoh ants and thief ants are especially problematic in June as their colonies have had time to grow large by this time of year. Outdoor ants like field ants, cornfield ants, and acrobat ants also frequently invade homes in June in search of food. Continued spring rainfall can flood ant nests, driving whole colonies indoors.
July is prime swarming season, so winged ants emerging from mature colonies often sneak into homes through cracks and crevices. This is especially true for Carpenter ants that mate and establish satellite nests in July. Odorous house ants, Argentine ants, and pavement ants also sustain high activity levels through July. The hot and humid conditions bring out sugar-feeding ants like little black ants, ghost ants, and crazy ants that invade kitchens.
While most ant species remain highly active in August, some begin winding down foraging as temperatures cool off in parts of the country. However, ants are still a major nuisance in most regions. Species like acrobat ants, thief ants, and carpenter ants continue invading structures. Rasberry crazy ants and little fire ants can suddenly show up in large numbers coming in from outdoors. Baiting and sealing entry points are important control methods in August to prevent ant trails from becoming established.
September marks the beginning of a decline in ant invasions as temperatures cool and colonies start going dormant for winter. Odorous house ants, Argentine ants, and pavement ants begin foraging less but can still pose issues early in the month. Carpenter ants also retreat back to main outdoor nests in September but may still enter houses sporadically through the month. Overall, proactive ant management in September can prevent severe infestations next spring.
While ants are most active from spring through fall broadly across the United States, their exact seasonal patterns vary by region according to local climate conditions:
Ants invade homes later in the year in colder northern states. Peak activity is typically July through September. Carpenter ants are especially common in northern homes during this period as they seek out warm indoor nesting spots.
The long, hot summers in southern states prolong the ant season. Ants become problematic as early as April and remain highly active through October. Southwestern species like leafcutter ants and harvester ants are more invasive during these months.
Coastal areas experience more consistent year-round ant activity. Warm, damp conditions promote infestations of moisture-loving species like Argentine ants and Pharaoh ants. However, invasions still intensify in mid-summer.
Identifying the ant species invading your home is key to proper control. Here are some of the most common ant pests in U.S. homes and businesses:
Small, light-brown ants only 1/16-inch long. They trail along the edges of floors and countertops foraging for sugary foods. Nest outdoors but invade structures. Most active April-October.
Odorous House Ants
Black ants 1/8-inch long with a strong foul odor when crushed. They search kitchens and bathrooms for sugary foods. Nest indoors or outdoors. Peak activity May-September.
Dark-brown or black ants with pale legs that build nests in pavement cracks. Invade structures in summer foraging for sweets. Most common June-September.
Tiny yellow or light brown ants only 1/16-inch long. Nests indoors year-round preferring warm humid spots like bathrooms. Ongoing issues, peaking June-September.
Large black ants up to 1/2-inch long. Tunnel into wood to nest and forage. Most active indoors July-September during mating season.
Yellow or brown ants with heart-shaped abdomens. Nest outdoors but enter houses for food and moisture. Common June-September.
Tiny ants under 1/16-inch long that seek outsweet and fatty foods. Steal food and nest indoors year-round. Peak activity May-July.
Little Black Ants
Extremely small sugar-loving ants that thrive in kitchens. Trail along countertops and floors. Persistent from May-September.
White, fuzzy ants about 1/16-inch long with a gradual tapered abdomen. Feed on sugary substances indoors. Active May-September.
Top 5 Questions about Ants in Houses
Here are answers to some of the most frequently asked questions about ants invading homes:
1. Why are ants coming inside my house?
Ants enter structures looking for food, water, and shelter. Common attractants are sugary spills, pet food, dirty dishes, moisture leaks, and cracks that provide entry points. Ants may also nest indoors in walls, attics, or under floors.
2. How do I get rid of ants in my house?
Use ant baits, caulk cracks, clean up food spills, store food in sealed containers, fix leaks, and vacuum up ants. Insecticide sprays or dusts applied into nests or entry points can also control ants. Getting rid of the entire colony is key.
3. What home remedies keep ants away?
Natural ant repellents include cinnamon, coffee grounds, black pepper, vinegar, lemon juice, and essential oils like peppermint, tea tree, and eucalyptus. Use them along ant trails and entry points. Diatomaceous earth also kills ants.
4. What months are ants most active inside homes?
Ants are most active indoors in late spring through early fall, roughly May through September, depending on your local climate. A few species like Pharaoh ants may be active year-round in warmer climates.
5. Should I use ant sprays or baits?
Baits are more effective since ants share the bait’s active ingredient throughout the entire colony. Sprays just kill ants you directly spray. Combine baits with sealing cracks for best control. Only use sprays directly into nests.
Preventing Ant Infestations
Here are some tips to help prevent ants from becoming a nuisance in your home:
- Clean up food spills and crumbs right away
- Store food in airtight containers
- Wipe down kitchen counters and floors daily
- Fix any water leaks or moisture issues
- Seal cracks and openings with caulk
- Keep screens in good repair
- Trim vegetation and branches touching the house
- Divert irrigation water away from the foundation
Denying ants access to food and water in your home goes a long way in preventing indoor ant infestations. Make your house as inhospitable to ants as possible.
Using Baits to Control Ants
Ant baits are one of the most effective ways to control ant invasions. The benefits of ant baits include:
- Worker ants bring the bait back to feed the rest of the colony, killing the queen and nest
- Easy to apply – no spraying required
- Child and pet friendly
- Long residual activity keeps working for weeks
- Multiple modes of action combat ant resistance
Follow these tips when using ant baits:
- Place baits along foraging trails and near nests
- Use enough bait stations to scope out the extent of the infestation
- Replenish baits until ant activity ceases
- Combine baits with sealing entry points for complete control
Baits containing active ingredients like abamectin, boric acid, fipronil, and indoxacarb work well against common household ants.
Why Killing the Queen Ant is Important
When trying to get rid of an ant infestation, killing the queen is key. Here’s why:
- The queen ant lays all the eggs to produce worker ants
- Queens can live over 10 years and lay thousands of eggs
- Colonies cannot survive without their queen
- New virgin queens may take over, allowing the colony to rebound
- Getting rid of the queen prevents the colony from growing and spreading
That’s why over-the-counter sprays that just kill worker ants provide temporary relief at best. Products containing fipronil, indoxacarb, abamectin, and boric acid target the queen ant as workers bring baits back to the nest. Killing the queen means no new ants can be produced.
Signs of an Ant Infestation
Watch for these common signs of ants living inside your home:
- Lines of ants trailing along walls, floors, and countertops
- Clusters of winged ants around windows and doors
- Ant mounds or nests in the yard near your home’s foundation
- Ants crawling under the home siding or around the foundation
- Sawdust piles from carpenter ants tunneling in wood
- Ants floating in pots or buckets of standing water
- Random ant sightings in kitchens, bathrooms, and pantries
Spotting ants emerging from cracks or gathering in areas like sinks and potted plants indicates they are nesting indoors. Swift action is needed to control ants before they multiply even more.
Sanitation is Key for Ant Prevention
Practicing good sanitation greatly reduces the chances of ants infesting your home. Be diligent about:
- Wiping down countertops
- Sweeping floors
- Cleaning dirty dishes promptly
- Taking out trash and recycling regularly
- Fixing leaky pipes and faucets
- Sealing up food packages and containers
Crumbs, spills, uncovered food, moisture, and other attractants motivate ants to enter and stick around. Cut off their food supply through daily sanitation practices. Clean house = no ants!
Ants naturally seek out the shelter and food sources inside people’s homes during warmer months. While ants themselves are not dangerous, their presence can create a nuisance and possible damage to your house. Protect your home by taking proactive measures to block ant entry, manage food sources, and eliminate active ant infestations through integrated pest control methods. With vigilance and persistence, you can keep ants out of your house and enjoy a pest-free home all year long.