Fall webworm 2.0
Source: Lee Townsend, Extension Entomologist Colonies of fall webworm caterpillars work together to encase terminal foliage of over 100 species of forest trees, shade trees, and shrubs in silk. Then, they feed together in this shelter for four to five weeks, expanding it as they need more food. The second of two annual generations is active in July and August.
Unsightly tents are usually the main concern for landscape trees. Healthy, established trees can tolerate light to moderate damage, but severe defoliation can increase susceptibility to other stresses, including borers.
Fall webworm infestations are most damaging to newly established trees and shrubs. Watch for the first signs of tent construction on ends of limbs and physically remove caterpillars and webbing as soon as possible. Insecticides labeled for caterpillar control on trees and shrubs can be effective, but spray coverage must be thorough.