We present new data on the host plants, biology, and distribution of Cosmobaris discolor (Boheman, 1836) and Hypolixus pica (F., 1798) (Coleoptera: Curculionidae). Larval host plants are ascertained for the first time for both species in the eastern Mediterranean region of Turkey. Amaranthus spinosus L. and Amaranthus viridis L. (Amaranthaceae) are the host plants of C. discolor. Immature stages of C. discolor develop inside the main stem and lateral branches of both plants. Amaranthus spinosus is a host plant of H. pica, whose immature stages develop inside the root system. This is a new country record for C. discolor in Turkey.