Surveys conducted in the South Okanagan Valley, British Columbia, revealed that a new leafhopper pest of grapes, the western grape leafhopper (WGL), Erythroneura elegantula Osborn, was widespread and often abundant in Vineyards on the east side of the Valley from just north of Penticton south to the United States border. Infestations occurred on drier upland sites where most commercial grape production occurs. The largest populations of up to 40 nymphs per leaf were recorded from commercial Vineyards that had applied reduced rates of the insecticide carbaryl for control of the Virginia creeper leafhopper, E. ziczac Walsh