Tlie known or actual host-plant range of Lema trilineata (Olivier) sensu latu was compiled from literature records, host records in insect collections, and original observations. The potential host range of L. trilineata daturaphila Kogan & Goeden was defined by means of a paired comparison test using leaf discs punched from 30 species of test plants and from Datura meteloides A. DC, the standard of comparison. Feeding was quantitatively evaluated using a photometric technique. Lema t. daturaphila apparently is restricted to the Solanaceae, showing a marked feeding preference for plants belonging to the genera Datura, Physalis, Atropa, Nicandra, and Salpichroa.