Eyes of the Female Twospotted Spider Mite, Tetranychus urticae.1 III. Analysis of Polarized Light2

Differences in response by females of Tetranychus urticae Koch (Acarina: Tetranychidae) to plane polarized light were limited to the near ultraviolet. It was postulated that the behavioral differences found resulted from changes in reflectance and were not a polartactic response. The differences in photoresponse between green and ultraviolet illumination resulted from small differences in acceptance angle of the anterior eye at low light levels to green and ultraviolet light, and the photoresponse of the posterior eye to ultraviolet.