Aphids on Weeping Willow: Identification and Management

A newly planted weeping willow developed yellowing leaves after overwatering. Now, clusters of tiny green insects cover the upper leaf surfaces, and ants are tending them.

Diagnosis: Aphids

The green bugs are aphids, common on willows. Ants "farm" aphids for their honeydew, protecting them from predators.

Control Options (Least to Most Toxic)

1. Blast with water: A strong jet from a garden hose dislodges many aphids.
2. Insecticidal soap: Spray thoroughly, covering leaf undersides. Repeat weekly as needed. Note: soap also kills beneficial insects.
3. Let ants manage: If damage is minor, ants may keep aphid numbers in check.

Prevent Recurrence

• Avoid overwatering—stress makes trees more susceptible.
• Encourage lady beetles, lacewings, and parasitic wasps by planting diverse flowering plants.
• Inspect regularly; early detection makes control easier.

Start with the hose; escalate only if necessary. The tree will recover with proper watering and pest management.