New records of scale insects (Hemiptera: Sternorrhyncha: Coccomorpha) from California with an updated checklist for the state

Six introduced species of scale insects (Hemiptera: Sternorrhyncha: Coccomorpha) were found for the first time in the environment in California in recent years, including three soft scales (Coccidae): Ceroplastes rusci (Linnaeus, 1758), Coccus viridis (Green, 1889), and Toumeyella parvicornis (Cockerell, 1897); one armored scale (Diaspididae): Aulacaspis yasumatsui Takagi, 1977; one ensign scale (Ortheziidae): Graminorthezia tillandsiae (Morrison, 1925); and one mealybug (Pseudococcidae): Nipaecoccus floridensis Beardsley, 2001. An updated checklist of all scale insect species known to occur in California is provided, including 485 species in 22 families and 140 genera, of which 307 (63%) are probably native and 177 (37%) have likely been introduced. Of the 307 native species, only 25 (8%) have been documented as pests in contrast with 147 (83%) of the 177 adventive species. The scale insect families in California represented by the highest number of both adventive species and pest species are Diaspididae, Pseudococcidae, and Coccidae.