A gardener described tiny, dark, wind-drifting insects (aphid-sized) on a willow tree that leave a reddish-purple stain when crushed. Unable to identify without a photo or specimen.
Likely Candidates
- Willow aphids (various species): Some produce colorful stains when crushed due to plant pigments.
- Willow leaf beetles (larvae/adults): Small, dark; may stain.
- Spider mites: Tiny, dark red/brown; stipple leaves; crush to red stain.
- Thrips: Minute, slender, dark; drift on wind; can stain.
Next Steps
- Collect samples: Tap branches over white paper. Capture insects in a vial with rubbing alcohol.
- Photograph: Close-ups of insects, damage, and whole tree.
- Consult a tree expert: This requires an entomologist or certified arborist. On this platform, Jim Hyland (Trees Forum) has US Forest Service experience.
- Local extension: Submit samples to your county Cooperative Extension office for free ID.
General Willow Pest Management
- Spray strong water jets to dislodge soft-bodied pests.
- Horticultural oil (dormant or summer) smothers aphids, mites, scale.
- Insecticidal soap for active infestations.
- Encourage beneficials: lady beetles, lacewings, parasitic wasps.
- Avoid broad-spectrum insecticides—they kill predators and worsen outbreaks.
Accurate ID is essential for targeted treatment. Use the Trees Forum or local extension.
