The compound eye is the main visual organ of insects and has the function of sensing size, shape and color. Research on the compound eye’s structure is the basis for understanding insect vision and the role of the visual cues in insect behavior. Compound eyes are usually categorized into two major types; apposition, and superposition, eyes. Superposition eyes perform well in low intensity light but have low resolution, whereas apposition eyes do not perform as well in low intensity light but have higher resolution. Most diurnal insects have apposition eyes whereas superposition eyes are mainly found in nocturnal species. Molecular biology, electroantennogram experiments and behavioral analyses reveal that insects are most sensitive to ultraviolet, blue and green light. Insects use celestial cues and ground targets for orientation and navigation, including the polarization of light from celestial bodies and the contrast between landmarks and background color. Different kinds of cues may be used simultaneously. Vision plays a crucial role in the process of finding hosts, mates and oviposition sites, and should not be underestimated in entomological research. Knowledge of phototaxis can provide a theoretical basis for the environmentally-friendly control of pests, such as developing species-specific traps.