Many different species of caterpillars feed on poplar leaves wherever the trees are grown. Depending on the species, the moths lay their eggs from early spring to midsummer. The larvae that hatch from these eggs feed singly or in groups on buds, on one leaf surface (skeletonizers), or on the entire leaf. Certain caterpillars web leaves together, or web a branch as they feed. In some years, damage is minimal due to unfavorable environmental conditions or control by predators and parasites. However, when conditions are favorable, entire trees may be defoliated by late summer. Defoliation weakens trees because there are no leaves left to produce food. When heavy infestations occur several years in a row, branches or entire trees may be killed.
Spray with an insecticide containing carbaryl or acephate, or with the bacterial insecticide Bacillus thuringiensis (Bt) when damage is first noticed. Cover the leaves thoroughly. Repeat the spray if the tree becomes reinfested.
Plant Care for Populus