Animals, on the other hand, undergo hibernation. The most well known example of hibernation is bears. Before hibernation, they collect their food and store it to be used during the winter. Then they lie down in such a manner that the heat loss from the body is minimized and that they are able to maintain a minimum level of body temperature. They also begin growing a heavy fur coat.
Another way of escaping from the cold is by migrating towards warmer areas. This is most common among aerial creatures. Birds migrate from the north to southern, warmer climates. Arctic Terns are well known migratory birds that fly thousands of miles every season. Some butterflies also migrate during winters, traveling extremely long distances.
Insects don't just disappear and magically reappear the next year. Each species has developed some way of dealing with the cold weather. One insect, as we have said, follows the example of the migratory birds and heads south.
The monarch butterflies fly from east of the Rocky Mountains, and eventually find their way to central Mexico, where they winter in the mountain highlands near Mexico City. One or two areas are protected as monarch refuges. Monarchs from west of the Rockies travel to a spot near Santa Barbara, California. Theseare true migrating insects because the same individuals that go south for the winter come back the next year.
For some other insects, such as leaf hoppers and milkweed bugs, the strategy for dealing with winter is also to head south as the winter cools. They re-invade the next year, but in this case, it's different individuals that return.
Most insects stay here year round. They employ a variety of tactics for survival. One is simply to move in with humans. Insects such as ladybird beetles (ladybugs), cluster flies, elm leaf beetles and box elder bugs overwinter as adults in wall voids, attics and other out-of-the-way places in homes and other structures. Before humans started building insect hotels, they probably found shelter in hollow logs and other natural cavities.
Many other insects spend the winter in immature stages - as eggs, as larvae underground or as pupae (cocoons).
The final group of insects are those that remain active all year round. These are primarily aquatic insects that spend the winter as immature in rapidly flowing streams that don't freeze all the way to the bottom. Some insects have body fluids that act like antifreeze. Glycol-like substances that resist freezing protect the insect from being torn apart internally by ice crystals.
With or without antifreeze, most insects simply cannot function at temperatures below 40 degrees F. Because they rely entirely on the world around them for the warmth they need to function, they've developed this wide range of techniques for surviving cold weather and assuring the survival of their species.
One of those techniques is to borrow the warmth from our homes. Can you blame them?
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