Why the world’s most destructive moth was recently renamed to the spongy moth

Nature · Published 3 October 2026 Swipe more like this →

In short: Lymantria dispar is a global ecological menace, defoliating millions of hectares of forest. Once known as the gypsy moth, the species underwent a formal name change in 2022. This shift reflects both the insect's unique biology and a growing sensitivity toward the cultural implications of its original, controversial moniker.

The name Lymantria dispar is derived from Latin, with the genus meaning 'destroyer' and the species epithet 'dispar' highlighting the stark sexual dimorphism between males and females. While the insect is native to Europe and Asia, its introduction to North America in 1869 by Étienne Léopold Trouvelot—who hoped to establish a domestic silk industry—triggered an ecological crisis. The moth is now classified as one of the world's 100 worst invasive species, with its range expanding by an average of 21 kilometers annually.

The transition from 'gypsy moth' to 'spongy moth' was driven by the Entomological Society of America. In June 2021, the society’s board moved to drop the old name, citing it as a slur against the Romani people. By March 2022, they officially adopted 'spongy moth,' a term inspired by the insect's distinct, porous egg casings. This change highlights the complex intersection of scientific nomenclature and social responsibility, acknowledging that even the names we give to pests carry historical and cultural weight.

Controlling the species has proven difficult. Early efforts to introduce biological agents, such as the tachinid fly Compsilura concinnata, often backfired by harming native insect populations. Today, the most effective tools are microbial pathogens like the fungus Entomophaga maimaiga. Despite an annual U.S. Forest Service budget of $30 million, the moth remains a persistent threat. Climate change is now exacerbating the problem, lengthening outbreak cycles and causing severe defoliation that ripples through ecosystems, even rendering trees unsuitable for other native species like the Polyphemus moth.

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