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Invasive Species: Spongy Moth
*Established in Michigan*
- Spongy moth caterpillars emerge from tan, fuzzy egg masses in April and feed on leaves through late June.
- Caterpillars are hairy, with a yellow and black head and 5 pairs of blue spots, followed by 6 pairs of red spots.
- Mature caterpillars are 1.5 to 2 inches in length.
- Leaf debris and small, round frass found under trees are indications of gypsy moth infestation.
- Male moths' wings have a wavy pattern of brown to dark-brown and span 1.5 inches.
- Female moths are larger than males and do not fly. Wings are white to cream with wavy black markings.
Spongy moth male (dark) and female (white). Photo courtesy of John H. Ghent, USDA Forest Service, Bugwood.org.
Spongy moth caterpillar. Photo courtesy of Haruta Ovidiu, University of Oradea, Bugwood.org.
REPORT THIS SPECIES
Use the Midwest Invasive Species Information Network (MISIN) online reporting tool
- Or - download the MISIN smartphone app and report from your phone - MISIN.MSU.edu/tools/apps/#home
ABOUT THIS SPECIES
Most often feeds on the leaves of oak and aspen but can also be found on hundreds of other plant species.
Europe and Asia
Northeastern U.S. west to Minnesota
Spongy moth caterpillars defoliate trees, leaving trees vulnerable to diseases and other pests, which may lead to tree mortality. During large outbreaks, debris and frass from feeding caterpillars can be disruptive to outdoor activities.
Pathways of Spread:
Though female moths do not fly, small caterpillars can be blown by the wind to other trees. Gypsy moth egg masses and pupae can be unknowingly transported on firewood, vehicles and recreational gear.
*A new common name for Lymantria dispar, spongy moth, replaced the prior name of this insect, gypsy moth, in 2022. We’ll be updating our resources in the coming months to reflect the change.