Do u know a cockroach stay live quite some week even his head cut off ? Yeah,its hard to believe.At first the cockroaches do not have blood pressure & they have an open circulatory system.Humans breathe through their mouth or nose but the cockroaches breathe through little holes in each body segment.So cockroaches are not dependent on the mouth and windpipe to breathe..Its a cold blooded insects & need much less food than humans do.Many Experiments have shown that cockroaches can easily live in a sealed jar without food for at least a month.The cockroach could last about a month without a need for its head.