Ants in Gardens and Lawns: When They Threaten the House

Ants are part of almost every garden. Most of them do useful work: aerating soil, eating other insects and recycling organic matter. But when nests move close to the house, or when the species is one that tends to invade buildings, garden ants become a household problem.

This guide explains how to tell when to act.

The short answer

Garden ants are usually harmless and even helpful, but they become a concern when nests are near the foundation, under paving or against walls, when trails lead into the house, when ants farm aphids on garden plants and spread to the house, when large, aggressive or biting species are present, or when ants undermine paving and lawns. Manage by keeping a clear gap between plants and walls, removing food sources and clutter, treating nests close to the house with baits or professional perimeter treatment, sealing entry points and monitoring trails. Leave distant nests alone.

Common garden ants

• Small black or brown ants nesting in soil, under stones and paving.
• Red ants that bite or sting.
• Carpenter ants nesting in dead wood and tree stumps.
• Weaver ants in trees, building nests of leaves.
• Harvester ants and others in open soil.

When they threaten the house

1. Nests along the foundation, under steps or against walls.
2. Trails running from the garden into doors, windows or cracks.
3. Ant activity in wooden fences, stumps or timber close to the house, which may signal carpenter ants.
4. Mounds under paving that cause settling.
5. Aggressive or biting ants near play areas and seating.
6. Honeydew-farming ants on plants against the house.

Garden management

• Keep plants, mulch and soil away from walls and the foundation.
• Remove wood piles, stumps and debris near the house.
• Manage aphids and sap-sucking pests on plants.
• Do not leave food, pet food or sweet drinks outdoors.
• Fix leaks and avoid water pooling near walls.
• Trim branches that touch the house.

Dealing with nests near the house

1. Find the nest by following trails.
2. Use baits that workers carry to the colony, placed where children and pets cannot reach.
3. For persistent or large nests, call a professional for perimeter treatment.
4. Seal cracks and entry points in the walls.
5. Avoid flooding nests or pouring chemicals, which scatter ants and may harm soil life.

When to leave them alone

Ants far from the house, with no trails inside, are generally best left alone. They do useful work, and removing them rarely helps.

Safety

• Beware of biting and stinging ants, particularly near children.
• Keep pets and children away from treated areas until safe.
• Take care with pollinators and edible plants.

When to call a professional

If ants are entering the house, damaging paving or in large numbers, call a professional.

Frequently asked questions

Should I kill all garden ants?

No. Focus on nests and trails close to the house.

Do ants damage lawns?

Mounds can disrupt them, but ants rarely kill lawns.

Do garden ants come indoors?

They can, following food or water.

Are ant mounds a sign of a problem?

Not necessarily, unless they are close to the house.

This guide is part of IPest's complete resource on ant control. For identification help, prevention and treatment options, see our full ant control guide for Bangalore.