Asian Gypsy Moth
Asian gypsy moth (AGM, Lymantria dispar ssp.) is an exotic pest not known to occur in the United States. Although in many ways similar to the European gypsy moth subspecies, AGM larvae have been known to feed on over 500 plant species, covering over 100 botanical families. In addition, the female AGM is an active flyer that is capable of flying up to 25 miles (40 km). This broad range of possible host plants combined with the female’s ability to fly allows the AGM to spread rapidly into and through uninfested areas. Large infestations of AGM can completely defoliate trees, weakening the trees and leaving them more susceptible to disease. If defoliation is repeated for two or more years, it can lead to the death of large sections of forests, orchards and landscaping. An introduction into the US would pose a major threat to the landscape of the North American continent.
The goal of APHIS-PPQ is to identify likely pathways for entry of this exotic pest and to maintain an early detection program that will allow us to act on any AGM introductions before the population becomes established. In addition to natural spread, humans are a potential source of long-range spread as eggs can be laid on ships, shipping containers, outdoor furniture, firewood, timber, rail cars, automobiles and other inanimate objects. These vehicles and materials can then be transported to new areas. AGM egg masses are extremely hardy and their tolerance of temperature and moisture extremes enhances the risk of spread.
One significant pathway that has been identified is via ships and cargo from the Far East. The USDA works in cooperation with the governments of Russia, Japan, China, and South Korea to minimize the risk of AGM introductions into North America through inspections and certifications of ships entering US ports. In addition, an agreement with the Russian government allows for detection surveys in Far East Russia, near several high risk ports, to determine AGM population levels. Analysis of these population levels helps determine, on a seasonal basis, the risk of introduction via ships and cargo coming from or transiting Far East Russia.
Although the AGM has never become established North America, there have been many instances where monitoring and trapping programs have identified AGM introductions. The first find was Asian gypsy moth egg masses on a Soviet ship docked in Vancouver, British Columbia, that were found to be hatching in 1991. Because it was feared that larvae may have blown onshore, steps were taken to detect and identify new gypsy moth introductions into northwestern North America. During the summer and fall of 1991, Asian gypsy moth adults were found in Portland, OR, and Tacoma, WA, in the United States, and in Vancouver, BC, in Canada. Swift regulatory and control actions were put in place and these localized populations were eradicated.
Since 1991 there have been a total of 20 introductions of AGM in Washington, Oregon, California, Idaho, Texas, and North Carolina, all of which were detected and eradicated before the pest could become established.
U.S. Customs and Border Protection (CBP) personnel have intercepted live Asian gypsy moth (AGM) egg masses on 37 ships and 18 containers between 2008 and 2011. These ships had called in Far East Russia, Japan, Korea, or Northern China during AGM flight season. In many instances, the ship had called in ports in all of those countries during the same voyage. Two of these interceptions, in Houston and San Francisco, were found to be hatching. Many of these events were severe enough to consider vessels significantly infested, resulting in the vessels being ordered into international waters. In all cases, delays in cargo unloading and clearance were significant. This resulted in major losses of revenue, since those ships were unable to conduct cargo operations, missed cargo charters, and experienced significant schedule delays.
These incidents can be avoided by adherence to predeparture certification and strict sanitation standards involving the removal and destruction of all AGM egg masses prior to departure from foreign seaports and arrival in the United States. APHIS-PPQ works closely with CBP on inspection procedures and decisions to order ships out of U.S. ports if found with AGM egg masses or other life forms.
Last Modified: March 27, 2012