Form and Function of Stemmata in Larvae of Holometabolous Insects

holometabolous insects, investigations of visual capabilities of larvae mediated by stemmata have been overshadowed by research on the amazing visual powers that adults achieve through compound eyes. this review, I synthesize a scattered literature which documents that many larvae are indeed capable of quite sophisticated vision. For some functions, such as neurophysiological bases of color vision, the assembled research demonstrates that the complexity of processing in many larvae rivals that known in adults. The sophistication of stemmatal function was not recognized because stemmata, single-lens eyes found only in holometabolous larvae, historically were confounded with ocelli, single-lens eyes found in adults of most orders and in immatures of most nonholometabolous orders of insects. Marcello Malpighi (78, p. 16) was probably the first to describe stemmata in his study of a satumiid caterpillar. In anteriori parte, ad latera tamen, globuli quidam, numero sex, diapheni protuberant, qui censentur. He also crudely figured the optic lobe of the caterpillar's brain (p. 47). Malpighi's Dutch contemporary, Jan Swammerdam, may have described the stemmata of culicine mosquito larvae (137, p. 96). Oculi nigelli, non-botryoides, non-reticulati, sed plani atque aequabiles. But the accompanying figure also shows the paedomorphically expressed compound eye. Swammerdam (138) described stemmata of other holometabolous larvae, such as the single stemma of Odontomyia (Diptera: Stratiomyidae) (p. 654), the six stemmata