Identification of Thrips (Thysanoptera: Thripidae) Feeding Sites on Sugar Maple Leaves

A method for rapidly identifying feeding sites of thnps on leaves is described. After an impression of the leaf surface is made using cellulose acetate film and acetone solvent, feeding sites are easily counted on the impression under a light microscope. When sugar maple, Acer saccharum Marsh., leaves exhibiting different degrees of damage by pear thrips, Taeniothrips inconsequens (Uzel), were compared using the method, we observed a close relationship between the degree of macroscopic dan:age symptoms and number of feeding sites per unit leaf area. The origin of feeding sites was further verified under laboratory conditions on sugar maple leaf disks fed upon by western flower thnps, Frankliniella occidentalis (Pergande). Feeding sites were found only on Impressions of leaf disks which were exposed to thrips.