Fall webworm

The Fall webworm (Hyphantria cunea) is a moth of the family Erebidae (formerly Arctiidae) that is well-known as a significant pest in both orchards and urban landscapes. Originating from North America, it has spread globally, becoming a serious threat to foliage in many temperate regions due to its aggressive feeding behavior.

This insect is a generalist defoliator known to attack over 300 species of trees and shrubs. Common hosts include apple, cherry, pear, walnut, and various maple and willow species. By targeting both fruit and ornamental trees, the webworm creates both economic damage and aesthetic degradation of the landscape.

The life cycle begins with overwintering pupae hidden in protected locations, such as leaf litter or bark crevices. In spring, adults emerge to lay eggs on the underside of leaves. Larvae are social and construct iconic silk webs around foliage, which protect them from predators while they feed and grow through several developmental stages.

The damage caused by the larvae is characterized by webbed nests that progressively expand as the caterpillars consume more foliage. Heavy infestations can lead to total defoliation of large branches or entire trees. This stress reduces the tree's ability to store energy, causing reduced vigor, poor fruit development, and increased susceptibility to secondary pests or diseases.

Recommended management strategies include:

• Pruning and destroying infested branches containing web nests before the larvae disperse.
• Applying biological insecticides, such as Bacillus thuringiensis, which are highly effective against young larvae.
• Encouraging natural enemies, including predatory bugs and parasitic wasps, which can help regulate population densities.
• Using chemical insecticides as a last resort, targeting early-instar larvae for maximum efficacy.
• Monitoring traps and visual inspections of tree canopies throughout the growing season to detect early signs of webbing.