Hibernation is the means for butterflies to survive the winter when there is no food and warmth. Each species hibernates in a certain stage of development. This may be the egg stage, or a caterpillar, chrysalis or adult. Butterfly species of the same family often have the same hibernation strategy. During the winter months the body water content decreases and the fluid thickens, thus enabling the butterfly to withstand the frost. Hibernating adult butterflies can become active in a heated room or attic, and should then be moved to a cold shed or garage.