The establishment since 1974 of colonies ofColeophora parthenicaMeyrick on Russian thistle,Salsola ibericaSennen and Pau, at 4 locations in southern California is reported. This stem and branch borer was successfully introduced from Pakistan. The larvae and pupae are parasitized in California by the solitary, external parasite,Norbanus perplexus(Ashmead) (Hym.:Pteromalidae). At current levels of establishment no control of Russian thistle has been observed.