The sugar beet crown borer—Hulstia undulatella—a relatively unknown lepi-dopterous pest of sugar beets caused severe damage to seedling and half-grown sugar beets in Yolo, Yuba, and Solano counties during 1949. Although it probably causes some damage annually it apparently has not been reported in the scientific literature as a California pest since 1905 when damage was reported at Chino, Huntington Beach, Oxnard, Spreckels, and in the Santa Ana Valley.