This species feeds on seeds of several species, mainly cypress. Since the end of the last century, it has extended its range from its native area in the Mediterranean Basin towards northeastern Europe and it is considered an invasive species. D’Hervé et al (2022) reported the presence of O. depressus from the New World and Southern Hemisphere.

Chamaecyparis Spach, Cupressus L., Juniperus L., Sequoiadendron giganteum (Lindley) J. Buchholz, Thuja L. (Cupressaceae), and Pinus
L. (Pinaceae)