Early spring occurrence of Empoasca Spp. (Hemiptera: Cicadellidae) in and adjacent to Alfalfa Fields in Iowa

Adult Empoasca fabae (Harris) (Hemiptera: Cicadellidae) were monitored at three locations within four alfalfa fields (edge of field to 40 m into field) from mid-April to June and Empoasca spp. activity from adjacent tree and shrub species until July. Similar numbers of Empoasca spp. adults were collected from sticky traps placed on tree and shrub species in the four border areas. In three of the four fields examined, significantly more E. fabae were found at the edges of the alfalfa fields closest to the trees than at 40 m from the edge of the field during the first week of May. In subsequent samples, there was no difference in the distribution of E. fabae in the alfalfa fields (except Field 2, where there were more E. fabae near the field edge for the duration of the study). Based upon this study, Empoasca spp. (primarily E. fabae) are colonizing alfalfa fields from the field margins to the interior in early spring and may be using adjacent woody habitats (including Gleditsia, Prunus, Ulmus, Tilia, and Quercus spp.) as a refuge when alfalfa is unsuitable.