Lymantria dispar asiatica
Distribution and Hosts
Established populations of Asian Gypsy Moth have been detected in China, Russia, Korea, Japan, and Germany where it was not known to occur until the USDA traced it back (AQIS, 2007). Although detected in North America, all populations have been successfully eradicated.
The Asian Gypsy Moth feeds on over 500 species of trees and shrubs, including many conifers and hardwoods, although Quercus is a preferred host. Other commonly encountered hosts include Alnus, Betula, Corylus, Larix, Malus, Populus, and Salix. The defoliation and weakening of hosts caused by Asian Gypsy Moth feeding increases their susceptibility to other pests and diseases and/or directly kills the host plant in some cases (APHIS-USDA, 2003).
Newly hatched larvae can be carried on wind currents, a process called "ballooning", this is the primary means of natural dispersal (Virginia Tech).
The Asian Gypsy Moth is a serious tree pest in its native Asian range. Due to similarities between Asian and North American ecosystems, it is a major threat to North American forests. This moth is a biotype of the European Gypsy Moth, which is already established in North America; the main difference is that the Asian Gypsy Moth has a wider host range, and females are active fliers, making it a higher threat if it were to establish.
Asian Gypsy Moth was first detected and identified near the Port of Vancouver in British Columbia, Canada in 1991, and in later moths were found in Washington, Oregon and British Columbia (APHIS-USDA, 2003). Ships from Russia inadvertently carrying viable egg masses are believed to be the source of these introductions. It is likely that the larvae hatched and were blown ashore while ships were docking. Asian Gypsy Moth was eradicated in the Pacific Northwest through trapping and spraying (APHIS-USDA, 2003).
Another infestation occurred in Sunny Point, North Carolina, but Germany was determined to be the point of origin. The eradication program for the intercepted North Carolina populations was completed in November of 1997. As of 2005, records indicate that so far the moth has been eradicated everywhere it has been found (APHIS-USDA, 2003; Campbell, 2004).
Description of Damage
Newly emerged larvae, or caterpillars, immediately begin feeding. Voracious feeding continues until pupations, with each caterpillar capable of consuming up to 1 square metre of foliage throughout their lifetime. In general, most feeding is nocturnal in order to protect caterpillars from predators and heat. Feeding damage can result in complete defoliation of a forest, or a section of a forest. Horticultural and urban trees are also at risk from defoliation.
This moth is very similar to the European gypsy moth, which is already established, in southeastern Canada and northeastern United States. The Asian gypsy moth has a wider host range and because adult females are active fliers (they can fly up to 30 km), they could spread quickly throughout the United States causing millions of dollars worth in losses. European gypsy moth adult females are flightless so their spread is much slower (APHIS-USDA, 2003).
Adult females are creamy-white with a wingspan up to 9 cm. Adult males are grey-brown with a wingspan of 4 cm (APHIS-USDA, 2003).
The egg masses are covered by a yellow fuzz from the females' abdomen (APHIS-USDA, 2003). Larvae may vary in colour, they have long hairs that cover the body and two rows of large blue and red spots on the dorsum (AQIS, 2007).
The Asian Gypsy Moth has one generation per year with four life stages, which include egg, larvae, pupae, and adult moth. Adult females will usually lay their eggs on trees, stones, walls, logs, and lawn furniture among other outdoor objects. Egg masses can contain more than 1000 eggs (APHIS-USDA, 2003). Newly hatched larvae can be carried on wind currents, a process called “ballooning, this is the primary means of natural dispersal (Virginia Tech 2008).
Eggs hatch in the spring, and the caterpillars begin constantly feeding on trees and shrubs leaves until pupatation occurs in June or July, depending on the temperature. Emerged from the cocoon, or pupae, occurs after approximately 10 to 14 days (APHIS-USDA, 2003).
The adult life stage only lives for one to three weeks, and their sole purpose is reproduction. No feeding occurs during the adult stage, and males die shortly after mating. Eggs are laid between July and September and remain dormant through the winter and hatch the following spring (APHIS-USDA, 2003; AQIS, 2007).
If gypsy moths are suspected to be present, local extension agents should be contacted before taking any action.
There are several biological control methods that have proven to be effective controlling both gypsy moth species.
The use of BT (Bacillus thuringiensis) has proven to be effective. It can take them between 7 to 10 days to die (APHIS-USDA, 2003; Virginia Tech 2008).
Nucleopolyhedrosis virus (NPV) is a naturally occurring virus that is effective against gypsy moth (Virginia Tech 2008).
Entomophaga maimaiga is a fungal pathogen of gypsy moths that was introduced from Japan. It is effective in high and low populations (Virginia Tech).
Ooencyrtus kuvanae is a tiny parasitic wasp that lays its eggs in the gypsy moth eggs within the egg masses (Virginia Tech).
The most effective non-disease control agent are mice, but birds, ants, shrews and ground beetles also feed on gypsy moths (Virginia Tech).
Mating disruption is another technique used in low to moderate populations where specific areas are saturated with a pheromone specific to this moth so when males emerge they are unable to find the females and mating is reduced (Virginia Tech).
For homeowners and professional pesticide applicators, ALWAYS read the label and follow the label directions. Do not forget that the LABLE IS THE LAW.
Chemicals such as Diflubenzuron or Tebufenozide that are insect growth regulators disrupt the larvae molting process are registered for gypsy moth control (Virginia Tech).
- APHIS-USDA. 2003. Asian Gypsy Moth. http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_phasiangm.html (November 24, 2008).
- AQIS, 2007. Field Guide to Exotic Pests and Diseases: Asian Gypsy Moth. http://www.daff.gov.au/aqis/quarantine/pests-diseases/forests-timber/asian-gypsy-moth (November 24, 2008).
- Campbell, F. 2004. Asian Gypsy Moth – Lymanthria dispar L. http://tncweeds.ucdavis.edu/products/gallery/lymdi2.html (November 24, 2008).
- Ellis, J. 2008. Indiana Gypsy Moth Information from Purdue Extension. http://www.entm.purdue.edu/GM/ (November 24, 2008).
- Virginia Tech. 2008. College of Agriculture and Life Sciences. Gypsy Moth in Virginia. http://fubyss.ento.vt.edu/vagm/index.html (November 24, 2008).
These materials may be used as long as the original author is given credit.