Cottonwood Leaf Beetle
- 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
- 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.