The seeds of 14 species, belonging to Cruciferae family, which are commonly available in Japan, were observed for the exudation of mucilage in water and for the ability of trapping and killing Aedes albopictus larvae. The seeds of two cultured Cruciferae, Brassica campestris rapifera L. cv. Yorii-kabu in Japanese, and B. c. oleifera L. cv. Natane, as well as seeds of uncultured Cardamine scutata Thund. and Capsella bursa-pastoris (L.) were proved to produce the mucilaginous layer and to trap and kill the larvae. Thirty-two heat-killed seeds of the above four species were soaked in the water together with mosquito larvae. The percentage of larvae attached in 24 hours were 39,47,70 and 49%, respectively. The mortality of these larvae in three days were 70,60,77 and 65%, respectively. Various numbers of seeds of C. scutata were soaked together with 100 larvae for three days. It has been shown that the mortality increased as the number of seeds soaked were increased.