Spongy Moth (formerly Gypsy Moth)
MODERATELymantria dispar
Overview
An invasive moth introduced to Massachusetts in 1869. Caterpillars defoliate hundreds of tree species, preferring oaks. Repeated defoliation weakens and can kill trees, especially when combined with drought stress.
- Type
- Insect
- Severity
- MODERATE
- Source
- iNaturalist
Symptoms
Large-scale defoliation of hardwood canopy, tan egg masses on tree trunks and outdoor surfaces, hairy caterpillars with blue and red dots feeding on leaves, extensive frass on ground beneath trees
Affected Species
Geographic Spread
Treatments
Btk (Bacillus thuringiensis var. kurstaki) Spray
Aerial or ground application of this naturally occurring bacterium that kills caterpillars when they ingest treated foliage. Highly targeted with minimal impact on non-lepidopteran species.
Egg Mass Removal
Scraping egg masses from tree trunks and surfaces into soapy water during fall and winter. Practical for individual property owners with moderate infestations.
Mating Disruption (Disparlure)
Aerial application of the synthetic female pheromone disparlure in the Slow-the-Spread program to confuse males and reduce reproduction in low-density populations along the expanding front.
Recommended Products & Tools
Helpful supplies for managing Spongy Moth (formerly Gypsy Moth). Always read and follow label directions, and confirm a diagnosis before treating.
Organic control that targets caterpillars when they're young.
Knocks down soft-bodied pests like aphids, mites, and scale crawlers.
Smothers overwintering eggs and crawlers; dormant or summer rates.
Soil-applied protection taken up by the tree for season-long control.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is Spongy Moth (formerly Gypsy Moth)?
An invasive moth introduced to Massachusetts in 1869. Caterpillars defoliate hundreds of tree species, preferring oaks. Repeated defoliation weakens and can kill trees, especially when combined with drought stress.
What are the symptoms of Spongy Moth (formerly Gypsy Moth)?
Large-scale defoliation of hardwood canopy, tan egg masses on tree trunks and outdoor surfaces, hairy caterpillars with blue and red dots feeding on leaves, extensive frass on ground beneath trees
Where is Spongy Moth (formerly Gypsy Moth) currently found?
Spongy Moth (formerly Gypsy Moth) is currently active in Connecticut, Delaware, Illinois, Indiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Virginia, Vermont, Wisconsin, West Virginia, District of Columbia. It has been reported in 20 total states across the United States.
What plants are affected by Spongy Moth (formerly Gypsy Moth)?
Spongy Moth (formerly Gypsy Moth) affects Apple, White Oak, Red Oak, Paper Birch, American Linden, Weeping Willow. Susceptibility varies by species.
How do I treat Spongy Moth (formerly Gypsy Moth)?
Treatment options for Spongy Moth (formerly Gypsy Moth) include: Btk (Bacillus thuringiensis var. kurstaki) Spray, Egg Mass Removal, Mating Disruption (Disparlure). Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.
Compare with Similar Ailments
Not sure if it's Spongy Moth (formerly Gypsy Moth)? Compare it side-by-side with similar ailments.