What's eating my thalictrum delavayi 'hewitt's double'?

Thalictrum 'Hewitt's Double' is a largely pest-resistant perennial. Aphids are the most likely pest, colonising soft young stems. Slugs may graze emerging growth in spring. Deer will browse the delicate foliage in US gardens. The airy habit and fine leaves make it less attractive to most chewing pests.

Colonies on young stems and underside of leaflets; slight leaf curling, honeydew deposits, and possible sooty mould. Remove by hand or with a water jet; apply insecticidal soap or neem oil spray; introduce or attract beneficial insects.

Young emerging shoots eaten or skeletonised in spring before plants harden off. Apply ferric phosphate pellets around the crown in early spring; remove mulch that shelters slugs; hand-pick after rain.

Tall delicate stems and foliage browsed in summer, particularly in US gardens near woodland edges. Apply deer repellent spray to emerging growth; fence the border or position plants among thorny or aromatic plants that deter browsing.