A comprehensive catalog of neuronal cell types in the Drosophila optic lobe has been compiled, revealing the connectivity rules governing these cells. The study identifies 227 intrinsic cell types, reducing the 38,500 neurons in the optic lobe to a simplified wiring diagram. The connectivity analysis reveals three families of cross-neuropil types and highlights the role of boundary neurons in connecting the optic lobe to the central brain. The study also identifies a new serpentine medulla interneuron family with the most types. The connectomic approach defines cell types based on similar connectivity patterns, enabling the identification of functional roles in motion, object, and color vision. The study provides a detailed classification of cell types, including their spatial coverage and connectivity patterns. The results suggest that the optic lobe contains specialized cell types for motion, object, and color vision, with the ON, OFF, and luminance channels playing key roles in visual processing. The study also highlights the importance of connectivity in distinguishing cell types and provides insights into the functional organization of the visual system. The findings have implications for understanding visual function and development, and may inform future research on brain function and artificial intelligence.A comprehensive catalog of neuronal cell types in the Drosophila optic lobe has been compiled, revealing the connectivity rules governing these cells. The study identifies 227 intrinsic cell types, reducing the 38,500 neurons in the optic lobe to a simplified wiring diagram. The connectivity analysis reveals three families of cross-neuropil types and highlights the role of boundary neurons in connecting the optic lobe to the central brain. The study also identifies a new serpentine medulla interneuron family with the most types. The connectomic approach defines cell types based on similar connectivity patterns, enabling the identification of functional roles in motion, object, and color vision. The study provides a detailed classification of cell types, including their spatial coverage and connectivity patterns. The results suggest that the optic lobe contains specialized cell types for motion, object, and color vision, with the ON, OFF, and luminance channels playing key roles in visual processing. The study also highlights the importance of connectivity in distinguishing cell types and provides insights into the functional organization of the visual system. The findings have implications for understanding visual function and development, and may inform future research on brain function and artificial intelligence.