Dwarf Willow Bagworms: Manual Removal Best for Small Trees

3-year-old willow: yellow powder on leaves, cocoons with tiny caterpillars inside.

Identification

Bagworms (Thyridopteryx ephemeraeformis). Spindle-shaped silk bags camouflaged with debris. Larvae feed from bag. Hosts: arborvitae, cedar, pine, spruce, cypress, juniper, willow, locust, sycamore, apple, maple, elm, poplar, oak, birch.

Control Options

1. Mechanical (BEST for small tree): Pick off and destroy bags.
2. Biological: Bacillus thuringiensis (Bt) spray late June (after egg hatch, ballooning done).
3. Chemical: Stomach insecticides (acephate, bifenthrin, carbaryl, chlorpyrifos, diazinon, dimethoate, malathion, etc.)—thorough coverage needed (larvae protected in bags). Early sprays (young larvae) work best.