06/19/2026
While this winged guy may seem to be a pollinator, he is not! Spongy Moths are an invasive species that feed on deciduous tree leaves and cause large defoliation throughout a forest. Once adults, they live only for a short period of time - long enough to mate and lay eggs. These foes of the forest form thick wool-like masses on tree trunks where eggs reside.
The native cousin of the Spongy Moth is the Forest Tent Caterpillar Moth. This little guy is also not a pollinator, but rather a food resource for our native birds and bats. They are high in protein and are a very important food source for young fledgling birds. While Spongy Moths are occasionally eaten by birds and bats as well, they are not the preferred food source for more than one reason.
Spongy Moth caterpillars are often not eaten like native moth caterpillars due to the large hairs on them. These hairs can upset bird stomachs. Bats will eat adult Spongy Moths but often times not in a volume high enough to affect the invading population.
Additionally, Spongy Moths can have 100-1200 caterpillars in a single egg mass whereas Forest Tent Caterpillar Moths typically have 100-400 caterpillars. This huge difference in emerging caterpillars is where the damage lies as many trees cannot handle 1200 caterpillars feeding on its leaves where as 100-400 caterpillars is a little more reasonable.
If you see signs of Spongy Moths please report to MISIN or iNaturalist. It is not currently known to be in the upper peninsula, so if you see any sightings within Marquette, Alger, Schoolcraft, or Delta counties, please contact us or the DNR Forest Health Division. You can reach us at (906)226-8871 ext. 3068 or email us at [email protected].
