Deerflies belong to the genus Chrysops into the family Tabanidae. Among other features, these tabanids are distinguished by the naked eye, often with spots or bands of different color. Antennae are cylindrical and longer than the head. The forehead is broad and has a very apparent frontal callosity .
While female deerflies feed on blood, males instead collect pollen. When feeding, females use knife-like mandibles and maxillae to make a cross-shaped incision and then lap up the blood. Their bite can be extremely painful, and allergic reaction from the saliva of the fly can result in further discomfort and health concerns. Adults are potential vectors of tularemia, anthrax and loa loa filariasis .
Vision Through the Colored Eyes of the Horse fly - Haematopota pluvialis
The conspicuous eye-color patterns of tabanid flies have been frequently portrayed. The eye colors originate from cornea color filters, which, on the one hand, cause colorful reflections and, on the other, alter the spectral composition of transmitted light.
The green/orange eyes of female Haematopota pluvialis (Diptera - Tabanidae) have four horizontal irregular dark brown stripes. The green/orange eye regions consist of a number of facets almost equal to the dark brown eye regions. Intermediate areas of red facets are small in extension. The spatial pattern of males is female-like, but reduced in size, and shifted to the ventral half of the compound eye.
It has been hypothesized that the external appearance of compound eyes, caused by the colorful reflections from the facets, serves as an intraspecific communication signal. And also the flies could benefit from the wavelength-specific, reduced transmission in terms of an improved perception of visual signals.