Lymantria dispar

Asian Gypsy Moth

Synonym(s): Porthetria dispar 
Class: Insecta
Order: Lepidoptera
Family: Lymantriidae  

Photographer: USDA



Adult Description: The Asian gypsy moth (Lymantria dispar) is from the family Lymantriidae, native to Asia. Male Asian gypsy moths have a forewing that is 20-24 mm long and the females have a slightly larger forewing measuring 31-35 mm. Males are active day and night in search of female pheromones, unlike many moths which are known to be strictly nocturnal. The female Asian gypsy moths are known for their flying ability with dispersion of 25 miles to lay eggs. Adults are often brown in color with some versions having a white overall body color. Both color morphs are known to have stripped patterns along the forewing and hindwing.  

Host Plant: The Asian gypsy moth has a broad host range of over 500 species of plants effected. Some of the preferred host plants are oaks, willows, lindens, poplars, birches, apple, elm, larches, and persimmon.

Ecological Threat: The Asian gypsy moth female is capable of flying distances of 25 miles allowing for aggressive dispersal of the species. Forests are at the greatest risk of damage from Asian gypsy moth establishment due to their ability to defoliate and damage trees. Defoliation can greatly reduce vigor or even kill the host tree. With the ability of rapid and aggressive dispersal the Asian gypsy moth has the potential to rapidly spread throughout the United States and cause severe damage to several forests on a large scale.

Biology: The Asian gypsy moth undergoes complete metamorphosis beginning with an egg stage, larval (caterpillar) stage,  followed by a pupae stage, and completed by an adult moth stage that looks drastically different from the larval form. Mature females lay egg masses often the size of a dime containing 1,000 eggs along the sides of trees, under rocks, logs, and other outdoor objects. The egg mass can be identified by a velvet coating that is yellow in color. The eggs hatch into the larval form in the early spring and feeding begins immediately. The larval feeding period lasts until June or July when a pupal phase begins where the caterpillar becomes dormant and metamorphose in to the adult form. Adult Asian gypsy moths do not feed for the 1-3 week remainder of the their life. Only mating and egg laying occurs in the adult stage. Eggs are laid between July and September and remain dormant until the following spring.

History: The Asian gypsy moth was first discovered in Washington State in 1991. It was believed that the insects were transported as larva on a ship from Germany that docked long enough for the larvae to emerge and transfer to shore via wind currents. This infestation was eradicated by joint federal agencies efforts through spraying and trapping. Another infestation was discovered in California from a ship that came from Europe. This population was also eradicated by the same management techniques. The prevention program of the Asian Gypsy moth ended in 1999 preceding another infestation in Portland, OR that was discovered in 2000.

U.S. Habitat: The Asian Gypsy moth can be found in a variety of forested areas where the host plants are found. With such a large range of host plants the Asian gypsy moth is not limited by availability of resources.


Native Origin: Asia  

U.S. Present: Pacific Northwest 


The most effective treatment for eradication of the Asian gypsy moth is by using a biological agent called Bacillus thuringiensis, which is a naturally occurring bacteria in the United States. This bacteria releases a toxin specific to the caterpillar and does not harm the tree. When B. thuringiensis is sprayed on infected areas of the host plant causing disruption in the caterpillar's digestion resulting in decreased appetite and death within 7 to 10 days of application. The general public can help by notifying federal or state forest agencies of suspected infestations of the Asian gypsy moth. Further assistance can be provided by compliance with precautions related to preventing the spread of the Asian gypsy moth as well as allowing local wildlife authorities permission to enter your property and treat areas of infestation by the Asian gypsy moth.


Asian Gypsy Moth Fact Sheet provided by APHIS. Plant Protection and Quarantine. April 2003.  

Barbosa, P.; Waldvogel, M.; Martinat, P. et al. 1983: Developmental and reproductive performance of the gypsy moth, Lymantria dispar (L) (Lepidoptera, Lymantriidae), on selected hosts common to mid-Atlantic and southern forests. Environmental Entomology 12(6):1858-1862.

Dwyer, G. & Elkinton, J.S. 1993. Using simple-models to predict virus epizootics in gypsy-moth populations. Journal of Animal Ecology 62(1):1-11.

Gansner, D.A.; Herrick, O.W.; Mason, G.N. & Gottschalk, K.W. 1987. Coping with the gypsy moth on new frontiers of infestation. Southern Journal of Applied Forestry Research 11:201-209.

Weseloh, R.M. & Andreadis, T.G. 1992. Epizootiology of the fungus Entomophaga maimaiga, and its impact on gypsy moth populations. Journal of Invertebrate Pathology 59(2):133-141.

Internet Sources


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