What’s on the van? – Silk Moth

This week’s What’s on the van? comes from Kotaro Fujiyoshi, a work experience student from Merchant Taylors’ school in Middlesex. He is currently on placement in the Museum’s Hope Entomological Collections.

This picture is of a silk moth called Rothschildia jorulla, which was described as a new species to science by the Museum’s first Professor of Entomology, John Obadiah Westwood (1805 –1893). It was collected in Cuautla, Morelos, Mexico in 1853.

Moths of this kind belong to a group called silk moths, or saturniids. There are over 2000 species of saturniids, one of them the world’s largest moth, Attacus atlas. This group of moths are widely exploited across many cultures as sources of silk. Some species of the group are very well known, for example the silk worm (Bombyx mori), used by Chinese textile manufacturers from at least 5000 years ago. This Rothschildia is no exception, as its silk has been used for producing textiles in Mexico.

Unlike their domesticated counterpart, the silkworm, this moth is very well adapted to a life in the wild. For example, its four translucent patches and two black eye-like spots on the wings can easily be mistaken for eyes. Birds looking for a meal would peck at these obvious vulnerabilities instead of the body, so that all the important organs and flight muscles of the moth are protected from a fatal blow.

Saturniids have reduced or completely dysfunctional proboscises (mouthparts) and do not feed. This means that they are very short-lived as adults, surviving for only about 2 to 3 weeks. They are able to survive these weeks without eating due to their energy stores: as caterpillars, they eat enough food to last them all the way from pupation to the end of their short few weeks as adults. After emergence, the males spend the majority of their remaining time fluttering about, looking for mates. Females emit sex pheromones, vital clues for the males, and the males smell their way to find their mates, using their comb-like antennae.

Saturniids are most diverse in the tropics and are often seen flying to house and street lights on relatively windless nights of warm seasons.