High angular and spectral selectivity of purple emperor (Lepidoptera: Apatura iris and A ilia) butterfly wings

Abstract

The iridescent features of the butterfly species Apatura iris (Linnaeus, 1758) and A. ilia (Denis & Schiffermüller, 1775) were studied. We recognized the structural color of scales only on the dorsal side of both the fore and hind wings of males of both of the aforementioned butterfly species. The scale dimensions and microstructure were analyzed by a scanning electron microscope (SEM) and transmission electron microscope (TEM). The optical properties were measured and it was found that the peak reflectivity is around 380 nm, with a spectral width (full width at half maximum) of approximately 50 nm in both species. The angular selectivity is high and a purple iridescent color is observed within the angular range of only 18 degrees in both species.

Coloration and structure of Taiwanese bronze scarab (Anomala expansa)

“…Nevertheless, the pattern of the surface structure of A. expansa resembles loosely arranged butterfly wings. 15,16 Iridescence is found in A. expansa, as shown in Fig. 3, in which two peaks, 555 nm (green) and 588 nm (yellow), shift as the angle of incidence changes.…”

Micro‐ and nanostructures of iridescent wing scales in purple emperor butterflies (Lepidoptera: Apatura ilia and A. iris)

“…Han et al (2008) reported that the type I scales in the clytie form of Apatura ilia are larger—150 μm long and 60 μm wide. The type I scales are responsible for the violet‐blue iridescence of Apatura ilia (Pantelić et al, 2011). Iridescent violet‐blue can be seen on the whole dorsal wing surface in males and is observed in narrow angular range.…”

“…Lamellae on the ridges of the type I scales are dorsally subtriangular, overlap, and form the multilayer structure responsible for iridescence (Fig. 2b; Pantelić et al, 2011). Lamellae exist dorsally on the ridges of the type II scales as well, but these are subcylindrical, slightly widened basally, only partly overlap, and do not produce structural coloration.…”

“…In our previous article, we started a study of its optical properties and this article is an in‐depth analysis of biological significance of submicron structures of Apatura spp. (Pantelić et al, 2011).…”

“…The dorsal side of the male wings of Apatura butterflies is of violet‐blue iridescent hue. This hue is caused by optical interference (Pantelić et al, 2011). Additional difference between the sexes is found in the structure of their fore legs that are larger in females, with five tarsomeres, while in males there are three tarsomeres.…”