Traps with synthetic pheromone are commonly used to capture males to help detect early infestations. Since then, defoliation has varied from under 1000 acres to over 5000 acres annually. Compared to neighboring states, Delaware has not yet experienced heavy deforestation of our approximately 225,000 acres of forested land. Defoliation effects depend on the amount of defoliation, the condition of the trees during and following the damage, the host itself and soil moisture availability. Some trees in some stands such as conifers will die with a single defoliation, but most broadleaf tree species can survive a single defoliation.
Defoliation weakens trees and leads to other stresses.
Refoliation uses tree energy reserves. Heavier infestations and subsequent defoliation may result in large numbers of trees dying. In heavy caterpillar infestations, even evergreens like pines and hemlocks may be defoliated. These are normally not preferred hosts. Effects of defoliation can be reduced by providing heavily defoliated trees with ample water during the summer following defoliation.