THE ORIENTATION OF HORSE FLIES AND DEER FLIES (TABANIDAE:DIPTERA): II. THE ROLE OF SOME VISUAL FACTORS IN THE ATTRACTIVENESS OF DECOY SILHOUETTES

Abstract

The attractiveness of colored spheres was compared in the field for several tabanid species. Black and red spheres were highly attractive to all the species. Tabanus illotus was attracted nearly equally to black, gray, and white silhouettes. The attractiveness of gray and white spheres for the other species decreased rapidly with increasing reflectance. Green and yellow spheres were unattractive for all species. Two-dimensional black silhouettes attracted only a small number of tabanids. Three-dimensional black silhouettes with plane surfaces attracted larger numbers of flies. Glossy black silhouettes with convex curvature in the vertical plane were much more attractive than other silhouettes. Interpretations of these results are presented.