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Insects and other arthropods

Spongy moth

Lymantria dispar

Tabs group


The two sexes are easy to distinguish: the females have white wings with black spots and thin antennae, while the males are darker and smaller and have feathery antennae. The wings are marked with wavy grey lines in both sexes. Their wingspan is 3 to 4 cm for males and 5.6 to 6.7 cm for females. The females are so heavy that they cannot fly.

In their last stage, the caterpillars are hairy and have small raised coloured spots on their backs. The spots nearest the head are blue, and those farther down the body, red. The head is black and yellow. The caterpillars may be up to 6.5 cm long.

Life cycle

The females, being unable to fly, emit pheromones (sexual hormones) to attract males. Once they have been fertilized, they lay from 100 to 1,000 eggs not far from their own cocoons, on a host plant or on stones, outdoor furniture or buildings.

The females then cover the egg mass with tiny tan or brownish fuzz from their own abdomen, to protect them during the winter. The eggs hatch in the spring and the caterpillars start eating as soon as they find food. In mid-summer, they stop eating and pupate. About two weeks later, they emerge as moths.

Geographic distribution

This harmful species originated in Eurasia and is now found in the US northeast and midwest, British Columbia and eastern Canada. They have been constantly spreading across North America since they were introduced.

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