One thing I've noticed about both the Long-tailed Blues and Common Blues I'm seeing in our area this season, is that they're more brown in colour compared to how we usually see them.
We have had an unusually hot, dry summer in New Zealand - even more so in the far north of the country where I live. Our fields are very dry and brown, although the habitat plant where these butterflies lay their eggs (birdsfoot trefoil) seems green enough.
I have read that, on butterflies, the scales form patterns and colours to provide them with camouflage that helps them hide from predators by easily blending in with the environment.
On further investigation I found this -
Despite their outward simplicity, the colors we see come from a complex chemical and structural system in the butterflies' wings.These colors come from two sources.
The first are pigmented colors which are simply ordinary chemical pigments that absorb certain wavelengths of light and reflect others. The wavelengths that are reflected are the colors that you'll see. An example would be that the shades of brown and yellow seen in most butterflies comes from melanin, the same pigment that tans your skin when you sit in the sun. When light hits the object it absorbs all the colors except the shades that create brown or yellow.
The second source of color is called structural color and results from the specific structure of the butterflies' wings. Butterfly wings are covered by lots of little scales which layer on top of each other and are separated by little pockets of air. Because of this structure color appears to shimmer and shift as an observer moves is actually a light effect known as iridescence. Iridescence occurs when light comes through transparent multilayered surfaces and is reflected more than once. All the reflections concentrate and compound each reflection, causing more vibrant visual displays of color. Using spectrophotometers like Instrument Systems' MAS 40, scientists have measured the degree of iridescence in both butterflies and other creatures like hummingbirds to gain an increased understanding of how these adaptations have effected their ability to survive as well as merely investigating how these structural effects influence animal behavior and development.
REF: Konica Minolta
When foliage is more dry and brown than usual (as in our current summer in New Zealand) it seems to me that the Blues may have made a few of their own colour adjustments in order to better blend in.
I wonder if others are noticing colour changes, in their own local butterflies, when the colour of the landscape changes dramatically during a butterfly season?
That certainly gives me something to think about 🦋