I saw a picture of a leaf cutter ant and some other ants. The leaf cutter ant has a white circle (eye) on the center of its head. I noticed other ants have something there also but in different arrangements of three spots or the coloration is different. What is this? What is it for?
The white circle you observed on the leaf cutter ant Atta cephalotes is a simple eye or ocellus. Ocelli occur in many other insect orders and function as auxiliary light sensory organs. Unlike the two main compound eyes, these simple eyes consist of a single ommatidium or "lens" and can perform only basic light/dark distinction. They are not typically found in the worker castes of most ant species but when they do occur, as in the genera Atta and Formica, they range in number from 1-3. The queens and males of all ant species always have 3 ocelli.
Thanks for your question,
Alexandra Westrich, Ben Rubin & the AntAsk Team