In 2018, an impression of a maize weevil, Sitophilus zeamais MOTSCHULSKY. or a rice weevil, S. oryzae L., was discovered on a potsherd from the Tian Luo Shan site, Zhejiang Province, China. This sample is the earliest archaeological record of this insect in China and possibly the earliest pest to harm rice grains in East Asia. To investigate the history of the evolution and propagation of rice pest insects in prehistoric East Asia, this paper evaluated the impression of the insect pest on a stored product. However, it was revealed that the harmed object might not be limited to rice because of the insect's bigger body size. In the previous report written in Japanese on the discovery of the weevil impression, it was identified as S. zeamais/oryzae without showing concrete length data of archaeological and modern weevils or detail key points for identification. And the report mainly focused on the history of origin and propagation of product food pest in the world. Therefore, this paper discusses diagnostic key points for identification as maize/rice weevil, with providing these detail data again.