Their body temperature rises and falls with the temperature surrounding them. This is the opposite of what people and other warm-blooded animals do. We maintain a constant, warm body temperature through all extremes with elaborate energy-using tricks to warm us when the world is cold, and to cool us off when it is hot. Their body temperature is hot in the summer and cold in the winter. During the cold-induced dormancy period, an insect cannot eat, grow, develop, reproduce or even move around.
Dormancy is an adaptation that improves the chances of surviving until warm temperatures return.
Each insect species has a range of temperatures suitable for activity. When an insect is either too hot or too cold it becomes dormant. It is active only at temperatures between the two extremes. To understand how an insect such as a specific kind of butterfly survives the winter, it is necessary to think about the life cycle. For example, swallowtail butterflies overwinter in the chrysalis stage attached to the plant foliage where the caterpillar fed.