Integrated Pest Management
Cottonwood Leaf Beetle
Chrysomela scripta
Cottonwood leaf beetle (Whitney Cranshaw, Colorado State University, Bugwood.org)
Gregarious larval feeding (Whitney Cranshaw, Colorado State University, Bugwood.org)
Cottonwood leaf beetle eggs (Whitney Cranshaw, Colorado State University, Bugwood.org)
Pest Description
- adults: 1/2 inch; yellowish with elongated black marks on wings
- larvae: black with six legs; resemble lady beetle larvae
- eggs: yellow; laid in clusters of 25 or more on the undersides of leaves
- other, similar-looking leaf beetles also feed on poplars and willows in the West
Host Plants, Diet & Damage
- poplar, cottonwood and willow
- feed on leaves, twigs and succulent bark of host trees
- larvae skeletonize and adults chew leaves
- damage may be localized or over the whole tree
- older defoliated trees may become stressed
- young trees may die after repeated defoliations
Biology, Life Cycle & Damaging Life Stage
- overwinter as adults in leaf litter or debris and under bark
- adults emerge when new leaf growth starts
- eggs are laid on the undersides of leaves
- larvae feed in groups on the undersides of leaves
- larvae develop into pupae on leaves in about 2 weeks
- pupation occurs for about 2 weeks and adults emerge
- two generations per year are common
- larvae are the primary damaging life stage, but adults also cause damage
IPM Recommendations
- Manage trees to improve or maintain overall health.
- Pesticide applications are not typically needed for this pest.
- Apply a pesticide (azadirachtin; Bacillus thuringinesis var. tenebrionis; carbamate) to foliage at egg hatch.