Like moths, butterflies have four wings covered with tiny scales. The front and back wings are usually zipped together, so that the insect looks as if it has only two wings. When a butterfly is not flying, its wings are usually folded over its back. The wings are patterned and are often brightly coloured. There are many different kinds of butterflies. The males and females of each kind are often slightly different from each other. Butterfly watching is a popular hobby. Some people also keep collections of dead butterflies that they have caught, but they find out that the colour fades.