Most insects typically have compound eyes that consist of thousands of tiny lenses called ommatidia. This unique structure allows them to have a broad field of vision and detect motion effectively. While many insects have two large compound eyes on their heads, some may also possess simple eyes called ocelli, which help with light detection and orientation. The total number of eyes can vary; for instance, a common housefly has two compound eyes but may also have three ocelli. Thus, the standard for most insects is two large compound eyes, reflecting their adaptation to various environments.