Science Questions

How do butterfly wings get all their colours? Katherine from Hartford

If the colours were down to inks or pigments, they would fade, just as if you wrote on a piece of paper and left it for many many years. If you go to the museums around the world, hundreds of years ago people collected some wonderful specimens of butterflies and moths that had some beautiful colours. If you look at those today, they still look spectacular. This means that they don't have inks. What they have got is a very clever arrangement of substances that bend and reflect light in just the right way using the structure of the shapes of what's in the wings to make those colours. It's what's called structural colour. The reason they have those beautiful patterns is actually down to camouflage and defence. Butterflies are a very juicy snack for things like birds and bigger animals, so they need to try and blend in with their environment. One way they can do that is to look the same as their environment, by having the same colour wings as what they like to live on. Other butterflies have shapes on their wings that look like a face. This scares off any potential predators. That's why they have their interesting colours.

October 2005