Samia cynthia

Samia cynthia, the ailanthus silkmoth, 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 (4.4–4.9 in), 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 forewings. The species was first described by Dru Drury in 1773.

Ailanthus silkmoth
Adult male and female
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Family:	Saturniidae
Genus:	Samia
Species:	S. cynthia
Binomial name
Samia cynthia (Drury, 1773)
Synonyms
Phalaena attacus cynthia Drury, 1773 Saturnia aylanti Motschulsky, 1858 Attacus walkeri Felder & Felder, 1862 (in part) Bombyx ailanthi Weil, 1863 Philosamia cynthia Grote, 1874 Philosamia cynthia Rothschild, 1895 Saturnia ailanti Fauvel, 1895 Attacus cynthia var. parisiensis Clément, 1899 Samia cynthia pryeri Jordan, 1911 (in part; misidentification) Philosamia cynthia advena Watson, 1912 Philosamia cynthia eulouvaina Watson, 1914

Eri silk

Eri silk fiber

Eri silk clothes

The common name, ailanthus silkmoth, refers to the host plant Ailanthus. There is a subspecies, S. cynthia ricini in India and Thailand that feeds upon the leaves of castor bean (Ricinus communis), 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]

Ailanthus silkmoth from Roxas, Panay island, Philippines

Range

Peigler & Naumann (2003),^[2] in their revision of the genus Samia, listed material of true Samia cynthia examined as follows:

Indigenous populations

• Asia: China (Zhejiang, Shanghai, Jiangxi, Jiangsu, Shandong, Beijing, Shanxi, Liaoning, Heilongjiang); Korea (North Pyongan, South Pyongan, Pyongyang, Kangwon, South Kyongsan, Chungcheongnam-do province)

Introduced populations

These include moths that have escaped from cultivation or were introduced and naturalized:

• Asia: Japan; India; Philippines; Thailand^[3]
• Australasia: Australia
• America: Canada; United States; Venezuela; Uruguay; Brazil
• Africa: Tunisia
• Europe: France; Austria; Switzerland; Germany; Spain; Bulgaria; Italy

Life cycle

Larvae

Ailanthus silkmoth diversity (with Actias luna specimens included in first two rows)

Eggs

Whitish eggs, marked with brown, are laid in rows of 10 to 20 on leaves in crescents. Hatching takes 7 to 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. There are five instars, and they reach a maximum length 70–75 mm (2.8–3.0 in).

Pupae

Eri cocoons

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.^{[citation needed]} Adult flight is during May and June in northern Europe, as one generation. In southern Europe a partial second generation may occur in September. Adults lack mouth parts and can neither eat nor drink.

Food plants

Larvae will feed on other trees and shrubs, but all eggs are laid on the "tree of heaven" (Ailanthus altissima) and growth is best on it. This tree is commonly grown as an ornamental in cities, but is considered a noxious weed and vigorous invasive species and is one of the worst invasive plant species in Europe and North America.^[4] The subspecies S. cynthia ricini feeds upon castor bean.

See also

• Sericulture