The insect nervous system is based on nerve nodules (ganglia) repeated in each body segment. While the ‘brain’ ganglion in the head is important, it is not the vital, all-controlling organ we see in vertebrates.
They also have an open circulatory system, rather than a network of blood vessels, and breathe through spiracles, or little holes in each body segment. So in theory it is possible for insects to live without their heads.
So how long can a cockroach live without its head?
The cockroach’s brain does not control its breathing and blood does not pump oxygen to the body. Instead, air is piped directly to tissues through a set of tubes called tracheae.
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Deprived of its head, the cockroach can therefore survive for hours or even days with little or no change to body function, breathing or metabolism.
It continues to function in terms of simple reactions. However, without its head the cockroach will be unable to eat, and so will eventually starve to death – though they can survive for weeks on one meal so this may take some time.
Equally, the cockroach’s head can survive without its body, moving its parts for several hours.
Also one note - don't try your own experiment
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