The Ailanthus silkmoth (Samia cynthia) is a saturniid moth, used to produce silk fabric but not as domesticated as the silkworm, Bombyx mori. The moth has very large wings of 113-125 mm, with a quarter-moon shaped spot on both the upper and lower wings, whitish and yellow stripes and brown background. There are "eyespots" on the outer fore wings.

Eri silk

The common name 'Ailanthus silkmoth' refers to the host plant. There is a subspecies, S. cynthia ricini in India that feeds upon the leaves of castor bean, and is known for the production of eri silk, and is often referred to by the common name Eri silkmoth.

The eri silk worm is the only completely domesticated silkworm other than Bombyx mori. The silk is extremely durable, but cannot be easily reeled off the cocoon and is thus spun like cotton or wool.^[1]

Range

Asia: Russian Far East, northeastern China as far south as Zhejiang, and Japan. Escaped from cultivation or introduced and naturalized in North America on the east coast,and France, Italy, Switzerland, Hungary, Austria, Croatia and Uruguay.

Life cycle

Eggs

Whitish eggs, marked with brown, are laid in rows of 10 to 20 on leaves in crescents. Hatching takes 7-10 days.

Larvae

Larvae are gregarious and yellow at first. Later instars are solitary, and whitish-green with white tubercules along the back, and small black dots. 5 instars, maximum length 70-75 mm.

Pupae

A silken off-white to grey cocoon is spun on the leaves of the host. It has an obvious escape hatch.

Adults

Females prepare to mate in the evening or night after emerging in late morning. Adult flight is during May and June in northern Europe, as one generation. In southern Europe a partial second generation may occur in September.

Food plants

Larvae will feed on other trees and shrubs, but all eggs are laid on Tree of heaven (Ailanthus altissima) and growth is best on it. This tree is commonly grown as an ornamental in cities. The subspecies S. cynthia ricini feeds upon castor bean.

Footnotes

References

Tuskes, PM, JP Tuttle and MM Collins. 1996. The wild silk moths of North America. Cornell University Press. ISBN 0-8014-3130-1 Saturnids of Western Palearctic

External links

• Butterflies and Moths of North America Ailanthus silkmoth ''Samia cynthia'' (Drury, 1773)
• Giant Moths (Saturniidae) of Prince Edward Island, Canada: ''Samia Cynthia'' (Drury 1773)

Gallery

<gallery> Image:Samia cynthia adult female sjh.JPG|Ailanthus silkmoth adult female Image:Samia cynthia adult male sjh.JPG|Ailanthus silkmoth adult male Image:Samia cynthia diversity.JPG|Ailanthus silkmoth diversity </gallery>

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