What do ocelli refer to in insects?

Ocelli are indeed referred to as simple eyes in insects. Insects typically have multiple types of eyes, and ocelli are distinct from the compound eyes, which consist of many tiny lenses. Simple eyes are usually small and are used primarily to detect light and dark, as well as to help with navigation. They do not provide the detailed imaging that compound eyes do. Instead, ocelli serve a crucial role in an insect's ability to orient itself in its environment, enhancing its ability to respond to changes in light. This is particularly important for functions like flight and hunting.

Compound eyes, in contrast, are made up of numerous individual photoreceptor units, allowing insects to see a wider field of vision and detect motion much more effectively. The other options—wings and legs—refer to anatomical features that serve different functions and do not relate to the visual system of insects in the same way that ocelli do. Understanding the specific roles of these anatomical components is essential for a comprehensive grasp of insect physiology and behavior.