Perhaps they migrate to avoid overpopulation, to find a new home when forced out by development, or deforestation, or even due to temperature changes. There are several reasons for migration, but none is known for sure. A few species are able to survive the winter in any stage of their life cycle by hibernating. During this time the insect goes into a period of inactivity. The body functions slow down so the insect does not need to eat.
Butterflies also have the outer skeleton around their body, which allows greater flexibility.
The most obvious difference is the scales that cover the wings and body. Another unique feature is their ability to roll up the proboscis, or the feeding tube. A butterfly s wings, as well as its entire body, are covered by thousands of delicate scales. These scales give the butterfly color and pattern. Each wing is made by two very thin sheets pressed together to protect a system of veins.