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Scientists warn that the invasive spongy moth, Lymantria dispar, poses a significant threat to West Coast forests. The moth, already causing damage in the Northeast, is spreading due to rising temperatures. A study published in January highlights the moth's potential to devastate California's oak forests, which cover millions of acres.
The spongy moth feeds on over 300 tree and shrub species, and its spread is exacerbated by global warming, which weakens the effectiveness of the Entomophaga maimaiga fungus, a natural predator that requires cooler climates. In late 2023, California officials trapped 16 spongy moths in Calabasas, marking the first significant infestation in Southern California. The California Department of Food and Agriculture has issued an emergency proclamation to eradicate the pests by 2026.
Computer models from the University of Chicago and Argonne National Laboratory predict that hotter, drier conditions will further limit the growth of the fungus, allowing more moths to survive and damage trees.
The spongy moth's defoliation not only affects trees' ability to photosynthesize but also leads to economic repercussions. The federal Slow the Spread program aims to curb the moth's spread through trapping, aerial spraying, and public education.