This week we have another photo from my recent trip to Alberta. You can recognize this horse fly as a male by its enlarged eyes that meet across the face in a narrow furrow. You can also see the pattern of light and dark bands across the eyes. This pattern is an example of structural color resulting from constructive interference in the insects cornea. The structure of these corneas differ between the light and dark bands causing the different colors we observe. The eyes of Tabanid flies are also interesting as they are able to use polarization-sensitive vision to find oviposition sites and vertebrate hosts for blood feeding.