tapetum
From ZooTerms (Dictionary of Invertebrate Zoology)
tapetum (noun; Latin tapete, carpet): 1. A reflecting surface within an eye.
2. (Arthropoda: Insecta) A light reflecting surface within clear-zone eyes, formed by tracheae that run through the eye parallel with the ommatidia forming a layer around each one, and reflecting the light back into the ommatidia.
