Leafhoppers of the genera Orocastus and Auridius are locally abundant in grassland regions in Western Canada. They are small insects, the males golden yellow and the females stramineous in colour. The two genera are distinguished from each other by characters of the internal male genitalia. The species are distinguished primarily by these characters and by the form of the seventh sternite of the female. There has been some confusion between the species, partly because the sexes were wrongly associated by some authors and partly because the extent of the individual variation was not appreciated fully. The following are descriptions and illustrations of the distinctive character; of the four species found in Canada, with notes on the distributions and variation. One species new to science is described and one species is reduced to synonymy.