Ants: how to recognise and treat it

Pest

Symptoms

Ants running up stems to colonies of aphids, scale insects or mealybugs; these colonies grow larger because the ants guard them from ladybirds and other predators.
Sticky honeydew and black sooty mould on leaves where ants tend sap-sucking insects.
Small heaps of fine soil above the nest in lawns, beds and pots.
Plants in pots or low-growing plants wilt quickly because ants loosen the soil around the roots, and low plants may be buried by excavated soil.

Tolerate ants wherever you can — they eat many other pests, and a destroyed colony is often replaced by new queens.
Band trunks of trees and shrubs with a sticky barrier and trim branches that touch other plants; on young trees put the band on a collar of paper or tape, not on the bark.
Water the nematode Steinernema feltiae into nests in beds and lawns; it may also affect other insects.
Soak a pot with an ant nest in a solution of insecticidal soap and water.

Ant bait stations with boric acid (borate), hydramethylnon or avermectin placed by trails and nest openings, away from crops; the ants carry the bait to the nest, so allow 5–10 days. Follow the label.
Avoid spraying pyrethroids around beds and paths — sprays kill only the ants they hit, and they pollute waterways.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Control aphids, scale insects and mealybugs, whose honeydew draws ants onto plants.
Brush ant heaps off the lawn on a dry day before mowing.
Keep plants, grass and mulch back from house walls, where ants like to nest.

Figures checked against these sources.