thumb|A L. dispar caterpillar

Lymantria dispar, also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae native to Europe and Asia. Lymantria dispar is subdivided into several subspecies, with subspecies such as L. d. dispar and L. d. japonica being clearly identifiable without ambiguity. Lymantria dispar has been introduced to several continents and is now additionally found as an invasive species in Africa, North America and South America. The polyphagous larvae live on a variety of deciduous and coniferous trees and can cause severe damage in years of mass reproduction. Due to these features, Lymantria dispar is listed among the world's 100 worst invasive alien species.

Etymology

The etymology of "gypsy moth" is not conclusively known; however, the term is known to have been in use (as 'Gipsey') as early as 1832.

Moths of the subfamily Lymantriinae are commonly called tussock moths due to the tussock-like tufts of hair on the caterpillars.

The name Lymantria dispar is composed of two Latin-derived words. The generic name Lymantria means 'destroyer'. The species epithet dispar means 'to separate' in Latin; it refers to the sexual dimorphism observed in the male and female imagines. In January 2022, the new common name "spongy moth" was proposed, as a translation from the French name "spongieuse" for the species, referring to the sponge-like egg masses laid by L. dispar.

Subspecies

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|L. d. dispar || Europe, western Asia and north Africa, || Females winged and capable of flight; attracted to lights Since then, several species of parasitoids and predators have been introduced as biological control agents in attempts to help control this moth. Beginning in the late 1800s, at least ten species were established this way, but for nearly a century, there was little regulation or research on the effectiveness or non-target effects of these introduced natural enemies. Several were generalists that offered little control of L. dispar and attacked other native insects. One such species is the tachinid fly Compsilura concinnata, which attacked many other host species (over 180 known hosts documented), laying waste many of the large moth species previously abundant in the Northeast. Another is the encyrtid wasp Ooencyrtus kuvanae which attacks L. dispar eggs but also parasitizes the eggs of other Lepidoptera species. The most effective control agents are microbial pathogens: a virus (LdmNPV), and a fungus (Entomophaga maimaiga).

Status in the United States

In June 2024, the severity of the outbreak in the Northeast and Midwest of the United States was reported in Scientific American. Some places in these regions were experiencing one of the most severe outbreaks ever recorded, with some areas reporting densities exceeding 2,500,000 caterpillars per hectare (1,000,000 per acre), and certain regions have been grappling with this issue for five consecutive years.

Since the introduction of the species to North America, L. dispar has caused significant ecological damage. Its range has expanded at an average rate of per year, resulting in the cumulative defoliation of of forest from 1970 to 2013. The U.S. Forest Service allocates an average annual budget of $30 million toward control efforts. However, climate change has contributed to longer outbreak cycles, which typically occur every eight to twelve years. This has led to a more frequent and severe impact on the environment.

Defoliation by L. dispar triggers chemical defenses in quaking aspen, rendering them unfit host trees for Polyphemus moths, posing an additional threat to that species' conservation.

References

  • Gypsy moth on UKmoths
  • Bugguide.net
  • Species Profile: European Gypsy Moth (Lymantria dispar) from the National Invasive Species Information Center, United States National Agricultural Library