Figure 1: Comparison of the externally typical compound eye of a Drosophila fly with that of a Halictophagus Strepsiptera. A) Small abutting facets constitute the compound eyes of this drosopholid, each of which resolves a single pixel. B) The ‘facets’ of this Strepsiptera are much larger because each one projects onto an extended retina, thereby producing multi-pixel images. They are also clearly separated. Because of such differences, the facets of an adult male strepsipteran’s eyes are often referred to as eyelets. Note that the ventral eyelets are much larger than the dorsal ones. This may represent a so-called acute zone of superior vision. (A) was taken from . (B) from .
All this peculiarity and ‘extra’ visual work invites one to ask why. What does an adult male Strepsiptera get out of his eyes? (BTW—adult females are blind, wingless, legless, and lack antennae1; but then, adult males starve to death in a few hours…) How well can they see? How did their eyes evolve and why has this eye morphology been retained? To address these questions I’ve been investigating Xenos peckii, a diurnal species, and Elenchus koebelei, a crepuscular species. Among many fascinating attributes, ostensibly Strepsiptera are the only order of insects in which the same eye design is used exclusively in all three major light regimes: broad daylight, dawn and dusk, and late night—so I have designs to work with a nocturnal species too. Stay tuned!
1. ^This is true of all but a single ancient lineage in which strepsipteran females retain eyes and legs. In that one clade, adult females can leave the body of their host, but they are still very lacking in mobility. This general inability to oviposit freely has led all strepsipteran females to give birth to live young that seek out their own hosts!
I am co-advised by Dr. Elke Buschbeck of the University of Cincinnati.