The citrus stubborn disease organism, Spiroplasma citri, has been cultured from beet leafhoppers collected from citrus near Riverside. This leafhopper is commonly a vector of curly top virus of sugar beets and other plants and is periodically abundant in hot, dry areas where sugar beets, citrus, and many other hosts are grown. This is the first report of a natural insect carrier of the citrus stubborn organism and is believed to be the first recorded instance of culturing a naturally acquired mycoplasma-like organism from an insect carrier.

This research was supported in part by a grant from the California Citrus Advisory Board. G. Cartia was sponsored by a fellowship from the Italian National Research Council.