Eyes in spiders and insects. (A) Dorso-frontal view of the eyes of an adult specimen of P. tepidariorum. Adult spiders usually have eight eyes: a pair of median eyes (ME) and three pairs of lateral eyes (LE): the median (MLE), posterior (PLE) and anterior lateral eyes (ALE). Note that the PLE and ALE share a common socket in the carapace. (B) Dorsal view of the head of an adult specimen of D. melanogaster. Insects also have median and lateral eyes, but these differ in morphology from those of spiders. The median eyes are simple ocelli, whereas the lateral eyes are multi-facetted complex eyes.