Why Brick Homes Attract Ant Colonies in Southwest MO & Northeast OK

Quick Answer (TL;DR)

Brick homes often attract ant colonies because mortar joints crack, brick holds heat, and the foundation area traps moisture—all conditions ants actively seek when choosing nesting sites. Research on ant nesting behavior shows colonies prefer environments with stable temperature, humidity, and protected cavities, which brick walls and foundations naturally provide. These factors are common in the Midwest and Ozarks due to clay soils, freeze–thaw cycles, and humid summers, making brick structures particularly attractive to ants.

Why Brick Homes Attract Ant Colonies

Across much of the Midwest and the Ozark region, brick homes are extremely common. While brick is durable and attractive, it unintentionally creates ideal nesting conditions for several ant species, including pavement ants, odorous house ants, and carpenter ants.

Understanding why ants are drawn to brick structures requires looking at how ant colonies select nest sites.

1. Mortar Joints Create Natural Nesting Cavities

Bricks themselves are solid, but the mortar between them slowly deteriorates over time.

Small cracks in mortar joints create entry points that ants can use to access:

• Wall voids

• Insulation cavities

• Foundation gaps

University extension research notes that many ants that invade buildings nest near foundation walls or under concrete slabs, taking advantage of structural cracks and voids for protection. Source: Perdue Ag College

Some species—especially pavement ants—are well known for nesting along building foundations and entering through cracks in masonry or basement walls. Source: Ag & Nature Resources College

Once ants locate a suitable cavity, they may establish satellite colonies inside walls while the main nest remains outside in the soil.

2. Brick and Masonry Retain Heat

Brick acts like a thermal mass, absorbing heat during the day and slowly releasing it at night.

This matters because ants select nest sites partly based on temperature stability.

Studies on ant nest structure show colonies are designed to maintain consistent temperature and humidity conditions for brood development. Source: Insectessociaux

Warm surfaces such as brick walls and foundations can create a microclimate that helps colonies:

• Develop larvae faster

• Remain active earlier in the season

• Survive cooler nights

This effect is especially noticeable in regions with cool springs and warm summers, such as Southwest Missouri and Northeast Oklahoma.

3. Moisture Collects Near Brick Foundations

Many ants prefer nesting sites with moderate moisture levels, which help maintain colony humidity. Source: MU Extension

Extension research shows indoor ant nests are frequently associated with moist areas inside wall voids, often near plumbing or other damp locations.

Brick construction can contribute to this in several ways:

• Mortar absorbs and holds moisture

• Foundation soil stays damp longer

• Irrigation and rainfall collect along brick walls

When these conditions combine with small cracks or cavities, the structure becomes an ideal nesting environment.

4. Foundations Provide Protection from Predators

Ant colonies require safe environments where they can build complex tunnel systems.

Research shows that ant nests typically contain multiple chambers and tunnels designed to maintain airflow, temperature, and humidity. Source: MDPI

Brick foundations and wall voids provide:

• Protection from predators

• Shelter from weather extremes

• Stable surfaces for tunneling and expansion

Once a colony becomes established near a home, ants can send out foraging trails that reach kitchens, bathrooms, and pantries.

5. Regional Soil Conditions Make It Worse

Homes in the Midwest often sit on expansive clay soils.

These soils:

• Expand when wet

• Shrink during dry periods

This constant movement leads to:

• Small foundation cracks

• Separation in mortar joints

• Gaps around windows and doors

Over time, these tiny openings create easy access points for ants searching for nesting sites.

Common Ant Species Around Brick Homes

In much of the Midwest and surrounding states, several species frequently take advantage of brick structures:

Pavement ants

• Nest under slabs and along foundations

Odorous house ants

• Often build colonies in wall voids or siding

Carpenter ants

• Prefer moist or damaged wood but may nest near brick foundations if moisture is present

Many of these species maintain multiple satellite colonies, meaning the ants you see indoors may originate from nests both inside and outside the structure.

Signs Ants May Be Nesting in Brick or Masonry

Homeowners often notice a few subtle indicators:

• Ant trails emerging from mortar joints

• Small piles of dirt or sand near foundation cracks

• Activity around window frames or brick ledges

• Ants appearing suddenly indoors during spring

These signs often indicate a nest somewhere in or near the structure.

Preventing Ant Colonies Around Brick Homes

Reducing ant activity typically involves eliminating nesting conditions around the foundation.

Helpful steps include:

• Sealing cracks in mortar joints

• Managing moisture near foundations

• Keeping mulch and soil from touching brick walls

• Treating foundation zones where ants commonly establish nests

Because colonies can extend several feet underground or into wall cavities, effective control often focuses on eliminating the colony itself rather than just the visible ants.