Bugs & Butterflies UK
Ailanthus Silk-Moth | Samia cynthia EGGS
Ailanthus Silk-Moth | Samia cynthia EGGS
The Ailanthus, or Tree of Heaven, Silkmoth is a large moth, with a wingspan ranging from 10 to 15 cm. Its wings are a rich brown or reddish-brown color, adorned with bold, cream or white triangular markings near the edges. These markings are outlined by darker borders, creating a distinctive appearance. The body is robust and covered with dense hairs, complementing the moth's overall warm tones.
Native to China and other parts of East Asia, Samia cynthia has been introduced to Europe and North America for silk production and as a biological control agent for Ailanthus altissima, its primary host plant. It inhabits areas where the Tree of Heaven is present, including urban parks, gardens, and forest edges. Introduced populations are established in Southern Europe, including parts of Italy and the Balkans, and the northeastern United States. In its native range, it can be found in temperate and subtropical forests.
Adult moths are nocturnal and have a short lifespan of about a week, during which they do not feed. Their primary purpose is reproduction. Males are strong fliers, actively seeking females by following pheromone trails. The caterpillars are large and green with a pale powder-like wax coat on their bodies. They feed almost exclusively on Ailanthus altissima, but they can consume other host plants, such as Willow (Salix), Plum (Prunus), Apple (Malus), Cherry (Prunus avium). The larvae spin tough, silken cocoons that are often attached to twigs or branches. These cocoons were historically harvested for silk production, though the silk is coarser compared to that of domesticated silkworms (Bombyx mori). Second brood cocoons overwinter and moths emerge the following spring.
The Ailanthus Silkmoth is a remarkable species that combines ecological significance with historical ties to silk production. Its striking appearance and adaptability make it a fascinating example of human influence on insect distribution and biodiversity.
Difficulty - Cocoons are easy (1/10); caterpillars are straightforward (3/10)
Host plants - Ailanthus; Privet; Lilac; Laburnum; Ash; Sweet Gum
Conditions - Room temperature or outdoors.
Lifecycle - Two broods per year; latter overwinters as cocoon.