Aggregations of the Potato Leafhopper in Alfalfa Fields in Wisconsin1

Abstract
Distinct aggregations of adult potato leafhoppers, Empoasca fabae (Harris), formed at margins and topographically elevated portions of alfalfa fields in southern Wisconsin during July and August of several successive years. Formation of aggregations usually coincided with periods of highest seasonal population density. Aggregation at elevated portions of fields appeared to be associated with microclimatic differences; aggregation at field margins may have been due to accumulation of migrants.