Ultrastructural data from 108 species of Chrysomeloidea show that all rhabdom‐patterns can be assigned to one of two basic patterns. The insula‐pattern: two central rhabdomeres (Rh 7/8) are spatially isolated from the six peripheral ones (Rh 1–6). The ponticulus‐pattern: Rh 7/8 fuse at two sites with the ring of Rh 1–6. The distance between the two systems may prevent optical or electrical coupling in the insula‐p. The structure of the ponticulus‐p may allow electrical coupling as well as contrast‐intensifying lateral filtering. Potential relative polarization and absolute sensitivities differ interspecifically between homologous cells and intraspecifically between Rh7/8 and Rh 1–6, and between Rh 7 and Rh 8. The Bruchidae show only the insula‐p, the Chrysomelidae and Cerambycidae both. The distribution of the two patterns is subfamily‐specific within the Chrysomelidae, but not in the Cerambycidae. Identical patterns must have developed convergently within the Chrysomeloidea. Both basic patterns are subdivided in different