Samia watsoni was reared in Yunnan from eggs received from Zhejiang in 2021. A mature larva was found in the field on Pterostyrax corymbosus (Styracaceae) in 2020, so this tree was used as the hostplant in captivity. Larvae accepted other Styracaceae in captivity. There are probably other hostplants in nature, but captive larvae refused Ailanthus and Liquidambar. The mature larva is light bluish green, white dorsally, with red dorsal scoli and others blue. In captivity the cocoons were wrapped in a leaf attached to the hostplants, but half were spun at the bottom of the cage with weak peduncles, suggesting that some cocoons may occur on the ground in nature. Adults were observed to drink water along the edges of streams, and a functional proboscis is reported for other Attacini.