The gypsy moth looms as a serious threat to our landscapes. Unfortunately, the gypsy moth is here to stay and we will never eliminate this pest from North America. We must all learn the facts about this insect. Management of the gypsy moth can be broken down into several categories. Each category has advantages and disadvantages, so a combination of treatments will result in a program with maximum effectiveness.
Predators and Parasites: Many bird species will consume gypsy moth caterpillars. Encourage birds to visit and nest on your property by planting shrubs for food and nesting cover. Mice, shrews, voles, chipmunks, and squirrels will consume caterpillars. Spiders, ground beetles, and ants also will play a role. Insect parasites exist that attack the eggs, larvae, and pupae. Unfortunately, predators and parasites will not effectively control gypsy moth populations during outbreak situations.
Diseases: Fungal and viral pathogens can be important in regulating gypsy moth populations, but above average rainfall is required during May and June. Populations may not be reduced by disease until after the caterpillars have reached mature size and most of the defoliation has already occurred.
Resistance: Avoid planting trees and shrubs favored by the gypsy moth. Caterpillars prefer to feed on oak, alder, willow, and poplar. They will avoid ash, tulip tree, honey locust, and holly. Mix up your plantings; don’t plant large groups of a single tree species.
Vitality: Provide your trees with the best growing conditions possible. Mulch the root zones under the tree canopies. Make sure your trees have adequate water and fertilizer to meet their needs. Lightly fertilizing your trees will help them maximize their chances for recovery. It will enable your trees to better tolerate gypsy moth injury and to replace lost foliage with less drain upon their energy reserves.
Reduce Stress: Avoid disturbing the soil through compaction or construction activities. Prune to remove deadwood and to promote new growth.
Read more about gypsy moth treatment methods.