Didius blue morpho

The museum treatment identifies this butterfly as Morpho menelaus didius, within Nymphalidae. Optical studies also use the species combination Morpho didius. [1][4][5]

The upper wing surface is predominantly blue with dark margins. The brown reverse bears eyespots and contrasting bands. [1][2]

The specialist catalogue gives Peru as the type-locality context. An identified Harvard specimen comes from Piura, Peru. [2][3]

The blue reflection arises from microscopic ridges and layered structures on the scales. Overlying cover scales modify light reflected from the more strongly reflecting ground scales beneath them. [4][6]

In a 2026 experiment, milling down the scale ridges reduced reflected intensity and shifted the main reflection toward ultraviolet wavelengths. Removing lateral lamellae instead reduced intensity while leaving the approximately 430 nm peak largely unchanged in that manipulation. [5]

Morpho menelaus didius treats didius as a subspecies of M. menelaus. Morpho didius treats the same named taxon at species rank and appears widely in the optical literature. [1][2][4][5]

The upper view shows blue reflection within dark margins; the reverse shows brown bands and eyespots. The apparent brightness of the blue changes with illumination and viewing angle. [1][4][6]

Flat blue fields and dark margins preserve the upper-wing pattern. The brown reverse retains its separate bands and eyespots within bold contours. [1][2]

Protect scaled wings from handling, abrasion, direct light and moisture. Keep the specimen in a stable, closed enclosure. [7]

Why are two scientific names used? Morpho menelaus didius is the subspecies combination followed here; Morpho didius is the species-rank treatment used in several optical studies. [1][2][4]

How is the blue produced? Layered microscopic ridges reflect selected wavelengths, and cover scales modify the reflection from underlying ground scales. [4][6]

Harvard and Butterflies of America provide the names and specimen records. Optical experiments describe the cover and ground scales, while the 2026 milling study tests the effects of changing scale dimensions. [1][2][3][4][5][6]