Hairy caterpillars grow up to two inches in length and display five pairs of blue dots followed by six pairs of red dots along their backs. Moths have an inverted V-shape that points to dot markings on their wings. Male moths have feathery antennae and are darker and smaller than females who have tan bodies and creamy white wings.


Only the caterpillar stage feeds, during a larval stage that lasts about seven to eight weeks. Caterpillars feed at the tops of branches; they begin by chewing small holes in the leaves then eat from the outside inward until the tree is stripped of its foliage.


Spongy moths have a number of natural predators, the most effective being small mammals. Other predators include birds and parasitoids.


Females possess wings but are unable to fly. Males fly in a rapid zigzag pattern in search of females but are capable of direct flight.

Reproduction and Life Cycle

Spongy moths have four stages of life: egg, larva or caterpillar, pupa and adult moth. Females lay a mass of 500 to 1,000 tan, fuzzy eggs in a sheltered area. The eggs remain here over the winter and hatch when the hardwood trees bloom in the spring. Once hatched, larvae feed for seven to eight weeks, pupate in a protected area for two weeks and emerge in moth form, when they will mate and start the cycle over.

Did You Know?

  • Spongy moths were accidentally introduced to the United States in Medford, Mass., in 1869, by a professor conducting silk research. They have been established in parts of eastern North America for more than a century.
  • Since 1980, the spongy moth has defoliated close to a million or more forested acres each year.

Sources and Additional Information