Ants on plants
Ants rarely damage plants themselves, but they protect sap-sucking pests for their honeydew and may nest in pots, drying out the roots.
Also known as: Ants farming aphids, Ant nests in pots
Symptoms and identification
Lines of ants running up and down stems, often to colonies of aphids, mealybugs or scale. In pots, soil may be fine and powdery, drain too fast, and contain ant nests and eggs.
Causes
Ants feed on the sweet honeydew produced by sap-sucking insects and defend those pests from predators. Dry potting mix attracts ants looking for nest sites.
Organic treatment
Treat the sap-sucking pests first. Put a band of sticky barrier or petroleum jelly on a strip of tape around tree trunks. To clear a nest from a pot, soak the whole pot in a bucket of water for 20 minutes.
Prevention
Control aphids, mealybugs and scale, which removes the ants' reason to visit. Keep pots evenly watered and stand them on feet away from walls.
Chemical treatment (use with care)
If ants are a persistent problem, use an ant bait station placed near the trail, away from children and pets.