In March 1994, Gonipterus scutellatus Gyllenhal, an Australian weevil that feeds on foliage of eucalypts, was discovered in Ventura County, CA. By the time of its discovery, the weevil was defoliating eucalypt trees in citrus orchard windrows. We imported, reared, and released a parasitoid of the weevil’s eggs, Anaphes nitens Siscaro (Hymenoptera: Mymaridae). A. nitens was firmly established in several southern California counties by mid-1997 and was spreading in tandem with its host. The wasp has proven to be effective in suppressing weevil populations, killing >95% of weevil eggs, except possibly in areas where insecticides are applied to manage pests of field crops. A. nitens appears to be a promising biological control agent for G. scutellatus in California.