Cockroaches are thought to be about 350 million years old, making them one of the oldest surviving creatures. They have been able to survive because of their rapid reproductive cycles and adaptability to poisons, environments, and even nuclear bombs. One of the largest is the Madagascar hissing cockroach, which has become a popular pet. Another large roach is Megaloblatta blaberoides, a resident of Central and South America. It has been measured at about 100mm long.
Some roaches can fly and one has been measured to have a wing span of about one foot.
Their ability to withstand radiation is very interesting. They have a very hard outer shell or exoskeleton, which is less prone to absorb radiation. Their skin molts, which means shedding, and this removes the radiation. In addition, they have an unusual different chromosome structure, which is difficult for radiation to shatter. The butterfly is similar to the cockroach in this respect.