Butterfly is a complete metamorphosis of insects, its life has four distinct developmental stages: (1) the egg stage (embryonic period); (2) larval stage (growth period); (3) the pupal stage (transition period); (4) adult stage (sexual stage). After the three developmental stages of postembryonic development are called. The four developmental stages of the performance of the body, from the morphological point of view, there is nothing in common. Therefore, it is necessary to study the system through the continuous observation, in order to understand that they are a species of four developmental stages. The four stages of development, and formed a circle of life, also called a generation. Butterfly circle of a life time, long or short, short several days, such as the cabbage, elders in the last three years (the) that such as Northeast Asian silk butterfly. The number of generations in the middle of a year is often different from that of the insect species. A year is a generation (such as Luehdorfia chinensis); multi generation (such as the cabbage), its number of generations often with the local high and low temperatures and different, they in Heilongjiang in only 2 to 3 generation, but in Guangdong can up to 5 ~ 6 generations. As for generations is named, since the start of the year, and at the end of the year, are called the first generation, second generation...... Etc.. In addition, according to the season and named generation. For example: adult emergence in the spring as the spring generation adult eclosion in summer said summer generations.