The beetles also feed on the young bark of seedlings, causing severely stunted growth and death. Cottonwoods and other suitable hosts are most severely damaged within the first three years of growth. Fall applications generally are not warranted. Inspection and Control Ants, ladybird beetles, lacewings, spiders, wasps, and various parasites feed on cottonwood leaf beetle larvae and eggs, offering some natural controls. When populations reach action threshold levels, insecticide applications may be necessary.
Young larvae are susceptible to insecticidal soaps and horticultural oils.
Control suggestions for cottonwood leaf beetle in New Mexico. Additional Reading Cranshaw, W., D. Leatherman, and B. Kondratieff. 1993. Insects that Feed on Colorado Trees and Shrubs. Colorado State University Cooperative Extension. Bulletin 506A. pp.