Cottonwood leaf beetle

Natural History
Adult Cottonwood Leaf Beetle
Photo credit: Bart Drees, Extension Entomology, TAMU

The cottonwood leaf beetle is one of the most destructive insect pests of poplars and willows in the southeastern United States. The insect can cause serious defoliation and injury to young plantations, nurseries and ornamental trees. Seriously defoliated trees are weakened and predisposed to injury by other insects (such as borers) and various pathogens. In biomass plantings, volume can be seriously reduced by repeated injury by the cottonwood leaf beetle. Damage is often most severe in newly established plantings and in nurseries.

Damage begins in early spring when adults emerge from under fallen leaves and weeds and begin feeding on new foliage. Adults mate and yellow, oval egg clusters of 25 or more are laid on leaf surfaces (usually undersides). Larvae hatch and begin feeding on the same leaf. Larve mature into pupate by attaching to plant surfaces and remaining stationary. Pupation usually takes 5-10 days and mature beetles emerge and complete the cycle. There can be multiple generations (up to 7 or more in the South). Usually, all life stages can be seen at one time. Management for cottonwood leaf beetle includes resistance, chemical control and pruning of damaged shoots.


 

Identifying Characteristics

Identifying the injury: Leaves in the upper portions (terminal) branches of cottonwood and willow trees first appear to be skeletonized (due to larval feeding). Later, leaves become ragged or are completely consumed leaving only petioles. Severe adult infestations can result in damage to young shoot tips and buds.
Identifying the insect: Adult beetles are about 6 mm long and light-yellow with black stripes/spots on the wing covers. Larvae are blackish with two yellow spots on each side.
Susceptible trees: The cottonwood leaf beetle can attack virtually any cottonwood/poplar (Populus spp.) or willow species. (Salix spp.)

 

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