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.

Reference: [1]

Photo credits: [Top: ©Lukas Jonaitis | Locality: Lithuania, 2011] - [Bottom: ©Eddie The Bugman | Locality: Willford, England, United Kingdom, 2014] 

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