Aphids and Ants on Young Swedish Columnar Aspen

Your 1-year-old Swedish columnar aspens have chewed leaves and ants on branches/trunk. The ants are farming aphids—not the primary problem.

The Real Culprit: Aphids

• Aphids suck sap, secrete honeydew (sticky, sugary).
• Ants harvest honeydew and protect aphids from predators.
• Aphid feeding curls and distorts leaves.

Control for Small Trees

1. Spray foliage thoroughly (both leaf sides) with acephate (Orthene) or insecticidal soap/pyrethrin.
2. Repeat in 7–10 days to catch hatchlings.
3. Once aphids are gone, ants leave.

Prevention

• Monitor weekly in spring/early summer.
• Encourage lady beetles, lacewings (avoid broad-spectrum sprays).
• Water adequately—stressed trees attract more aphids.

Bottom Line

Kill the aphids; the ants are just a symptom. A foliar spray on small trees is easy and effective.