Ants in Potted Plants: Aphids, Honeydew and Fixes

If your pots are full of ants marching up and down the stems, the ants are rarely there for the plant itself. More often, they have found a sweet reward: honeydew from aphids, mealybugs or scale insects feeding on the plant. The ants protect these pests in exchange for the honeydew.

This guide explains the relationship and how to fix it.

The short answer

Ants in potted plants usually indicate sap-sucking pests such as aphids, mealybugs or scale, which excrete sticky, sugary honeydew that ants harvest and defend. Ants may also nest in the potting soil, particularly in dry or well-drained pots. To fix it, find and treat the sap-sucking pests, remove the honeydew, deal with the ants through baiting or by blocking access to the plant, check the soil for nests, and keep pots clear of food and clutter. Treating only the ants will not stop the pests, and treating only the pests will not remove the nest.

The ant and aphid partnership

• Aphids, mealybugs and scale feed on plant sap and excrete honeydew.
• Ants collect the honeydew as food.
• Ants defend the pests from natural enemies such as ladybirds, helping the pests multiply.
• Large numbers of sap-sucking pests can weaken plants.

Signs

1. Ants trailing up and down stems and leaves.
2. Clusters of tiny insects on new growth, buds and undersides of leaves.
3. Cottony white patches (mealybugs) or small bumps (scale).
4. Sticky leaves and sooty black mould on leaves.
5. Curled, yellowing or stunted growth.

Fixes

• Treat the pests: Remove aphids and mealybugs by wiping or spraying with water, then use soapy water or a plant-safe treatment as suited to the plant. Check the label.
• Clean the honeydew: Wipe leaves with a damp cloth.
• Block ant access: Keep the pot isolated, with leaves not touching walls or other plants, and place the pot on a stand with legs in water or a smooth barrier.
• Check the soil: Look for ant nests. Repot with fresh soil if needed and soak the soil thoroughly.
• Bait the ants: Place ant bait near the trail, out of reach of children and pets, rather than spraying the plant.
• Encourage natural enemies: Ladybirds and other predators help in gardens.

Prevention

• Check plants regularly for sap-sucking pests.
• Avoid overfeeding with nitrogen fertiliser, which encourages soft growth that pests like.
• Keep plants healthy with good light and watering.
• Do not leave food or sweet drinks near pots.

Edible plants

Take extra care with herbs and vegetables. Wash produce before eating, and avoid strong chemicals on food plants.

Indoor plants

Isolate affected plants, and check neighbouring ones. Ants and pests can spread.

When to call a professional

If ants keep coming despite your efforts, a professional can find the nest and treat the surroundings safely.

Frequently asked questions

Do ants harm plants?

Mostly indirectly, by protecting pests, though some nest in roots and disturb them.

Is the sticky stuff harmful?

It is sugary and encourages sooty mould. Wipe it off.

Can I use cinnamon or pepper?

They are unreliable. See our guide on natural deterrents.

Why are ants in the pot soil?

They may nest there. Check and repot.

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.