Problem
How do I deal with aphids on my yarrow?
Achillea millefolium
Aphids on a yarrow usually has one of three causes — watering, light or a pest. Walk through them in order before reaching for a treatment.
Most likely causes
Detailed cause-by-cause guide is being prepared. In the meantime: check watering rhythm, sunlight match, and any visible pests on the underside of leaves.