Effects and Impacts

During most years, gypsy moth in its native range is found at low densities and causes little damage. At varying intervals, which depend on local conditions and natural enemy abundance, the gypsy moth population will reach high densities and can cause completely defoliation of host trees. Most impacts of AGM are associated with the physiological stress in trees caused by defoliation, especially if it occurs several years in a row or in conjunction with drought. These effects include reduction in tree growth, crown dieback and tree mortality. Tree mortality is usually associated with attach by other insects (wood borers) or pathogenic fungi. In urban settings, the most important impacts are on the health of valuable shade or street trees and during outbreaks caterpillars become so numerous that they become a nuisance to people. In addition, the hairs on the larvae and the scales on the adult's wings contain histamine, so people will suffer allergies from being exposed to them. Outbreaks typically last 1 to 5 years and the length of the period between is highly variable in the native range. Outbreak populations then decline because of starvation and increased disease. 

Interceptions of AGM in the United States will result in an eradication program, when a reproducing population is suspected, especially in areas that do not already have gypsy moth established. The eradication treatments involve multiple aerial sprays of biorational pesticides often over residential areas and at huge costs. In addition to the sprays, intense surveying for males using pheromone traps is done to delimit the population and confirm eradication. To help prevent the need for eradications, the gypsy moth populations in areas in Asian near ports are being monitored so that we will know when the risk of AGM moving on transport vehicles or their cargo is higher. Also, ships from these areas are inspected more carefully when they were in the Asian ports at the time of year that AGM is active.

For further details log on website :
https://www.nrs.fs.fed.us/disturbance/invasive_species/asiangm/effects_impacts/