a butterfly's wings

A co-operative butterfly from the butterfly garden

There’s a butterfly garden not far from where I live. It’s not huge or fantastic, but the air inside is delightfully jungley and the place is great fodder for my imagination (apparently my imagination is full of how I might inhabit a jungley domed space where I could grow my own bananas).

The best thing about the space is sitting to watch the erratic path of the butterflies (while ignoring the resident cockroaches). Unlike our resident swallowtails and cabbage butterflies, these ones are tropical with over-the-top flashy colouring.

Butterflies do use an assortment of pigments for colouring. But, the vividest, iridescent colours use the optical trick of structural colours (I’ve written about this before here, or if you doubt me check out here).

Look at a butterfly wing really closely or under magnification, you’ll see that the wings aren’t a smooth surface. Like a fishes body, the wings are covered in scales - in fact, the etymology of their order name, Lepidoptera, means scaled wings (lepidos is Greek for a scale and tera is wing). This scale structure is fragile, which is why touching a butterfly's wing can compromise its ability to fly.

A close-up of a butterfly wing

These scales are made up of many transparent layers that cause the light to interact with itself to create the awesome colours.