Nature's miniature solar panels: the thermal properties of butterfly wing scales and their evolution

The wings of butterflies are covered in thousands of scales
that have evolved to serve a range of functions including
aerodynamic efficiency, colour signalling, camouflage,
hydrophobicity and thermoregulation. Fundamental to
these functions is the nanostructure of the scales.
Interest in organisms' adaptation to their thermal
environment has grown in recent years as we try to
understand and predict how organisms will respond to
climate change. Butterflies are one of the best-studied
insect groups with respect to thermal adaptation. They are
also somewhat unusual in having large, scale-covered
wings, which they use for thermoregulation, both to absorb
solar radiation to warm up and to radiate heat away from
the body to cool down. While the importance of the wings
for thermoregulation has been known for some time, only
recently has the importance of the wing scale
nanostructures begun to be appreciated.