Diel settling patterns of female and male potato leafhoppers (Homoptera : Cicadellidae) on alfalfa

Settling of male and female potato leafhoppers, Empoasca fabae (Harris), we re compared over a diel regime (16:8 [L:D] h) on alfalfa, Medicago sativa L . cultivar 'Ranger', in the laboratory. On average, >80% of the females and 50% of the males were recorded on stems. Leaves were used more frequently by males than by females, but little use was made of the upper leaf surface by either sex. The proportions of both males and females on stems declined over time, whereas over time the proportion of males increased on leaves. Based on stem and leaf surface area available to leafhoppers, both sexes pr eferred stems and avoided leaves. Scotophase did nor appear to alter the dy namics of leafhopper distribution. Females more frequently caused expressio n of injury symptoms in the alfalfa stems than did males in a 36-h access p eriod. Thus, use of females in electronic monitoring and other feeding stud ies of adults for assessing injury to plants is supported for studies that are 36 h or shorter and where gender is not germane.