Listen to part of a lecture in a biology class. Okay, let\'s talk about butterflies. As most of you probably know a butterfly undergoes radical changes in the course of its transformation from an egg to an adult butterfly. People have been fascinated by this metamorphosis for 1000s of years. The butterfly life cycle has four stages. The first stage is the egg; the second stage is the larva. That\'s what most people refer to as a caterpillar. The third stage is the pupa, and the fourth stage is the adult butterfly. So for the first stage, the female butterfly has to deposit her eggs on a plant that has a lot of edible leaves. That\'s because when the eggs hatch, the larva is basically eating machine. It needs tremendous amounts of food to sustain its rapid growth. Once it\'s grown to its full size, which takes about two or three weeks. The larva attaches itself to a twig or a blade of grass and becomes a pupa. The pupa is encased in a hard outer shell. From the outside it may appear to be totally lifeless. But inside the shell, some pretty amazing transformations are taking place. The structure of the larva is breaking down And being replaced by the structure of an adult butterfly. If this process proceeds without any interruption an adult butterfly can emerge within two weeks but some pupae may remain dormant. That is, they may remain in a resting state for a lot longer than that and we\'ll talk more about that in a minute. When the adult butterfly emerges from the pupa, its wings dry out and harden and the transformation is complete, you then have a fully formed adult butterfly. Now, typically, a large group of butterflies from the same species will emerge at around the same time, say, in the spring. each one of these groups that emerge is called a brood that b, r, o, o, d. butterfly species in cooler climates, where the summers shorter generally produce only one brood per year. A nice example is the brown elfin butterfly. In the spring, the brown elfin females lay their eggs. In the summer, the eggs hatch and the larvae feed until they turn into pupae. During the fall and winter, the pupa rests, and then the following spring, the next brood emerges. so one brood per year. But in warmer climates, most butterfly species will produce two broods per year. the second brood emerging late in the summer. Now what\'s interesting is that the same species can be single brooded in cooler climate zones and double brooded in warmer climate zones. And what\'s also interesting is that the number of broods produced is often tied in with the size of the butterflies. In other words, you can have the same species and when it produces just one brood. the butterflies that emerge are often bigger than when that species produces two broods per year. you know, maybe in a warmer climate zone. So it\'s often the case that the fewer the broods. the bigger the butterflies. The more broods, the smaller the butterflies. And speaking of size, when you see a small butterfly. It\'s not a baby butterfly. it\'s a small, full sized adult. That\'s because butterflies reach their full adult size before they emerge from their shell. Now you have a lot of possible variations in butterfly life cycles and variations can give a species new avenues to develop and evolve. It\'s possible, for example. that at some time, you\'ll have a unique set of circumstances. maybe some unusual environmental conditions. and the next thing you know, you have a brown elfin butterfly flying in the fall. Just because we haven\'t yet observed a brown elf and butterfly flying in the fall doesn\'t mean it can\'t happen. I mean, we\'re now discovering that even in warmer climate zones. some pupae may remain dormant for two, three or even four years if there are unfavorable conditions, say a drought or a flood.