The potato leafhopper (PLH) is a serious pest of vegetable, forage, and fruit crops in the eastern and midwestern United States. PLH does not overwinter in the northern portion of its infestation range, since the insect can survive year-round only in certain areas of the southern United States where the frost-free period exceeds 260-270 days/year. Adults move northward each year in a mass migration in late April or early May. The first migrants are primarily females, and over half of these have been fertilized prior to migration. The number of annual generations in northern states varies from l-6, depending on time of arrival, host availability, and temperature.