This study reports the first complete life history of Antheraea castanea Jordan, 1910. Samples collected from the southeastern borders of Yunnan and Tibet were reared on specific species within the family Lauraceae, confirming that A. castanea is univoltine in captivity. The complete mitochondrial genome sequences of A. castanea and Antheraea youngi Watson, 1915, both belonging to the subgenus Antheraeopsis Wood-Mason, 1886, are provided. Genomic and morphological evidence demonstrates that A. castanea is the sister group to all other Antheraeopsis spp. This finding strongly supports the hypothesis that this subgenus originated in the southeastern regions of the Himalayas, making A. castanea a key taxon for understanding the evolutionary history of the genus Antheraea Hübner, 1819. Given its long-standing neglect in sericulture, we recommend increased attention to A. castanea in future studies—particularly to prevent misidentification with the muga silkmoth, Antheraea assamensis (Helfer, 1837), which shares similar habitats.