Presented below is digital image captured with a confocal laser scanning microscope of a Drosophila (fruit fly) eye imaginal disc from the third instar larval stage that has been has been double-labeled using green and red fluorophores (the Hairy gene is labeled in green and Cubitus interruptus (Ci) in red).

Fruit Fly Imaginal Disc: Eye (Low Magnification) Specimen: Drosophila Imaginal Disc Technique: Fluorescence (Double Label)

The fruit fly's normal eye color is reddish-brown, but genetic mutations produce a wide variety of defects that are helpful to geneticists in tracing genes and following their developmental patterns. As an example, a mutation that has been mapped to a defect on the X-chromosome, results in flies having yellow eyes. Some mutations cause the flies to have eyes that turn out pink, green, or white, while other mutations can produce flies that express an eyeless gene.