Japanese Silkmoth

2023 October 1

On August 19, 2023, Sam sent me these pictures of an enormous moth that they found while they were on their trip to Japan. It had clearly had a run-in with a predator (most likely a bat or a bird) that had ripped off part of its hindwings. But, since the body was unscathed and it still had plenty of wing area to fly, it escaped to fly another night.

The enormous feathery antennae pretty much mark this as a male moth. And from the size and the wing markings, it is pretty obviously the Japanese Wild Silk Moth, Antheraea_yamamai.

These are distinct from the moth species normally raised to produce silk, which is Bombyx_mori and has been domesticated to the point that it can no longer live in the wild. The Japanese Silkmoth is in a different genus than the domesticated silkmoths, and in fact it is much more closely related to the Polyphemus moths that we have here in Michigan. They actually look similar too, except that the Polyphemus moths have bigger eyespots on their hindwings, as we can see in this Polyphemus Moth that I photographed back in 2014:

The Japanese Silkmoths are actually cultivated to produce silk in Japan, and a number of its close relatives are cultivated in other parts of Southeast Asia and India. The silk they produce is called “Tussar_silk“, which has a different texture from “regular” silk and also has a naturally golden-yellow color.

The Japanese Silkmoth caterpillars normally eat leaves from any of the several varieties of oak trees, although they will also eat the leaves of beech, chestnut, hornbeam, and various trees and shrubs in the rose family.

They have been imported into Europe in the past to start a local tussar silk industry, and they have escaped from cultivation and become established in parts of Italy, Austria, the Balkans, and even as far north as Germany. They don’t seem to be a particularly “pesty” species, though. They are apparently just a nice addition to the European moth population.

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