Abstract
This paper presents descriptions of four new species of the genus Psylla, brief notes on their biology and records the encyrtid Prionomitus mitratus (Dalm.) as a parasite of Psylla ribesiae (Crawford). Of particular interest is the fact that two of the four new species occur on Ribes spp. and previously were not distinguished from the common species, ribesiae, which has been known in western United States since 1911.