Pest identification
What's eating my yarrow?
Aphids
Signs: Clusters of small insects on flower stems and bud clusters; slight distortion; sticky honeydew below.
Control: Knock off with a water jet; usually self-limiting because yarrow attracts abundant beneficial predators — avoid spraying unless severe.
Spittlebug / froghopper (Philaenus spumarius)
Signs: Frothy 'cuckoo spit' blobs on stems in May–June; minor sap loss; rarely causes lasting harm.
Control: Wipe or wash off the froth and nymph by hand; no chemical treatment needed in most cases.
Powdery mildew (Erysiphe spp.)
Signs: White powdery coating on leaves and stems in hot, dry conditions; foliage yellows and distorts with heavy infection.
Control: Improve airflow by thinning stems; water at the base to keep foliage dry; apply potassium bicarbonate spray or diluted neem oil.
Keep yarrow pest-free
Healthy plants resist pests best. Get the basics right:
Yarrow pests — FAQ
What is eating my yarrow?
Yarrow is one of the most pest-resistant garden herbs; its ferny foliage deters many insects. Aphids can still cluster on flower stems in dry spells, and spittlebugs (froghoppers) suck sap in spring. Powdery mildew is more of a problem than insects. Yarrow rarely needs pest intervention — good airflow is the main preventive.
How do I get rid of aphids on yarrow?
Clusters of small insects on flower stems and bud clusters; slight distortion; sticky honeydew below. Knock off with a water jet; usually self-limiting because yarrow attracts abundant beneficial predators — avoid spraying unless severe.
How do I get rid of spittlebug / froghopper (philaenus spumarius) on yarrow?
Frothy 'cuckoo spit' blobs on stems in May–June; minor sap loss; rarely causes lasting harm. Wipe or wash off the froth and nymph by hand; no chemical treatment needed in most cases.
How do I get rid of powdery mildew (erysiphe spp.) on yarrow?
White powdery coating on leaves and stems in hot, dry conditions; foliage yellows and distorts with heavy infection. Improve airflow by thinning stems; water at the base to keep foliage dry; apply potassium bicarbonate spray or diluted neem oil.