The Madeira mealybug, Phenacoccus madeirensis Green, 1923 (Hemiptera: Coccomorpha: Pseudococcidae) is a highly polyphagous, invasive pest species that is actively extending its geographical range. There has been some uncertainty as to how to separate it reliably from a less invasive species, P. gossypii Townsend & Cockerell, 1898, due to the occurrence of intermediate morphologies. In this study, molecular and morphological analysis of Phenacoccus mealybugs intercepted on fresh plant material entering California provided evidence that there is a complex of undescribed cryptic species around P. madeirensis.