Black Soldier Fly Vision

The visual system of adult BSF consists of two simple eyes (ocelli)and a pair of large compound eyes.

Ocelli allows flies to detect and response quickly to changes in light intensity, which can help them avoid obstacles and predators.
Compound eyes consist of >1000 small units, i.e., ommatidium. It contains 6 photosensitive parts, named as rhabdomeres (R1-R6), posited at the edge.

The rhabdomeres of two smaller cells (R7, R8) reside in the center of the ommatidium. R1-R6 represents a spectrally homogeneous class of photoreceptors with a broad spectral sensitivity, physiologically purpose for motion detection while less for color discrimination (except for Drosophila).

Photoreceptors R7 & R8 have narrow spectral sensitivities. Specifically, R7 has a peak sensitivity in the UV, while the R8 are most sensitive to blue or green light. Thus, photoreceptors R1-R8 enable BSF a version based on 3 channels, i.e., UV-blue-green.