Which butterfly species have the most ommatidia?

The number of ommatidia is a direct measure of an eye's potential resolution. The species with the most ommatidia are generally the largest, fastest, and most active fliers, as they require superior vision for navigation and spotting food or mates from a distance.

While it is difficult to name a single "record holder" for all 180,000 species, the butterflies in the family **Papilionidae (the Swallowtails)** are consistently cited as having some of the highest counts.

For example, some species like the European Swallowtail (*Papilio machaon*) or other large tropical swallowtails are estimated to have **17,000 to 25,000 ommatidia per eye**. This is an exceptionally high number and provides them with very sharp, wide-angle vision, which is necessary for their fast, agile flight. In comparison, a housefly has only about 6,000 ommatidia.