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Tree Fruit Insect Pest - Spongy Moth

Spongy moth, Lymantria dispar, may attack fruit trees, especially apple, causing defoliation that can stunt or kill young trees.

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Updated:

February 25, 2026

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Orchards may be invaded by young spongy moth larvae ballooning long distances on silk threads. Photo by G. Krawczyk.

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Description and life cycle

Egg masses deposited in July on trees, rocks, and other surfaces hatch the following year in April and May. Orchards may be invaded by young larvae that balloon long distances on silk threads. Larvae pupate in mid- to late June, and adults emerge in July. Females cannot fly.

Monitoring and management

Trees should be inspected in early June.

If spongy moth larvae are found, they may be removed by hand and destroyed, or killed with an insecticide. Bacillus thuringiensis-based compounds are effective insecticides with low toxicity to other animals.

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