What's eating my koelreuteria paniculata?

Golden rain tree is generally pest-resistant but susceptible to a specialist: the box elder bug in North America clusters on seeds in autumn, and the flatheaded borers can attack stressed trees. Aphids appear on new growth in spring. In the UK and US, scale insects are the most consistent recurring threat.

Crusty or waxy bumps on bark and twigs; honeydew and sooty mould on leaves; dieback of small branches in heavy infestations Spray crawlers with horticultural oil or insecticidal soap in summer; apply dormant oil in early spring; improve tree vigour to reduce susceptibility

Colonies on soft new growth in spring; curled and sticky leaves; sooty mould following heavy infestations Encourage ladybirds and hoverflies; knock off with water; apply neem oil or insecticidal soap if needed

D-shaped exit holes in bark; serpentine galleries under bark; dieback of branches, particularly on stressed or drought-affected trees Keep trees well watered and healthy to resist attack; remove and dispose of heavily infested wood; avoid trunk injuries from mowers or strimmers