Mealybugs Killing Japanese Yews: Identification and Control

Cobwebs Are Likely Mealybugs

Japanese yews dying over 2 years show small cobwebs on lower branches. Not spider mites—yews resist typical yew pests.

Mealybug Signs and Damage

• White, cottony masses in branch crotches and on stems.
• Suck sap, causing yellowing, browning, and death.
• Produce honeydew leading to sooty mold.

Effective Treatment

Spray highly refined horticultural oil thoroughly, especially interior branches. Repeat per label. Oil suffocates all life stages. Systemic insecticides (e.g., imidacloprid) can supplement. Improve air circulation via pruning.