Spanworms are the larval stage of the Winter Moth. They hatch early in spring and start feeding on new and developing leaves of many trees and shrubs. If left unchecked, Spanworms will feed on the foliage of plants causing unsightly chewing of the leaves. They will feed for two to three weeks and reach about an inch in length. In late spring, they drop to the ground using a silky thread, which can be a nuisance as they often land on patio furniture and even people passing by.
For control of this pest two important treatments are recommended. First, is an application of a sticky band to the trunk of the susceptible trees (see Sticky Banding for more details) and the second is the treatment of the tree canopy in early spring.
One of the best features of naturally derived products is that they are highly specific; meaning they only affect certain species of insects and do not affect earthworms, honeybees, birds, mammals etc.