Cockroaches are unpleasant, tenacious pests that are notorious for their resilience and ability to live in harsh environments and circumstances. They are known to be one of the most invasive and disliked creatures on the planet with some disgusting characteristics, leading to many people asking why they even exist?
Another well-discussed topic about cockroaches is: can a cockroach survive without its head?
Cockroaches can survive without their head for around 2 weeks depending on several factors. Their anatomy and behavior are well suited for surviving long periods without their primary sensory areas. Roaches without a head can’t eat, but they may survive by using stored-up fat from other body parts. Cockroaches can survive dehydration by reducing their breathing rate to prevent water loss.
The insects’ heads contain their only primary sensory inputs, so if this area of the body is damaged or removed, it will cause dysfunction and problems.
Decapitation is what usually makes losing a head lethal. However, headless cockroaches can’t even bleed to death – their vascular systems are built to avoid critical drops in blood pressure and uncontrollable blood loss.
Even still, the cockroach will not be able to feed or drink and dehydration and starvation will kill it in a matter of a few days, sometimes even up to two weeks.
How Can Cockroaches Survive Without Their Head?
What makes these creatures interesting, but at the same time totally disgusting is their ability to survive without what we would consider the most important and critical part of our bodies – our heads.
To understand how cockroaches can achieve this it is important to understand their anatomy makeup. Numerous scientific studies have taken place by The University of Illinois around the unusual characteristic of cockroaches and to explain this gruesome fact several areas of their anatomy should be considered:
A Headless Cockroach Can Survive Without a Brain
The head of cockroaches is the only part housing vital organs and control mechanisms, so losing it means certain death. However, their brain consists of about three percent of the insect’s weight which is relatively small. Unlike humans, roaches don’t rely much on their brains to operate their bodies.
In order to perform all of their biological functions, cockroaches use a simple nerve cord. The nerve cord is similar to a human’s spinal cord and can send signals from the head to the back of the insect’s body.
They Can Also Survive Without Antennae
Cockroaches’ antennae are used as their primary sensors and they can use them to feel their environment and navigate through it. This is also the first sense affected by a cockroach’s decapitation. The insect will first lose its ability to smell, touch and taste which makes it truly helpless.
Since the legs of cockroaches contain small sensory hairs, the insects can still feel their way forward. This will help them to find food and water if they are nearby enough. The bug can also detect physical contact with the surface which gives it an idea of where it is moving towards.
The most important thing to note is that cockroaches are not able to see after losing their head. This means that they are unable to use any of their senses to detect potential dangers or food sources. Their ability to smell and feel the surface isn’t enough for them to find anything without having vision too.
In order for a decapitated roach to live, it has to be really close to food and water or have them served directly into its mouth. This is why they are often seen near sources of both, especially in the kitchen after dark where they are looking for crumbs on the floor.
A Headless Cockroach Won’t Suffocate
A cockroach’s respiratory system is designed differently than a human’s or other animals. Scientific studies have shown that they breathe through spiracles, small openings found on each body segment and the base of their legs. Headless roaches can’t use these spiracles to breathe, but they can survive up to two weeks without breathing because of the way they circulate air through their bodies.
The respiratory system of a cockroach is made up of small holes in the body and spiracles at their base which takes oxygen into their trachea. The roach circulates air through its body by closing off these spiracles and opening others, switching between open and closed spiracles. This creates waves that move along the roach’s body and push oxygen through the roach.
A Cockroach Won’t Bleed to Death
Unlike humans, a cockroach doesn’t have blood pressure therefore it can’t maintain a certain level of blood in its body. This also means that the insect is unable to control the amount of bleeding by constricting arteries.
Cockroaches don’t have a developed circulatory system like humans or other animals. A lower number of blood vessels implies that less blood may exit when they are opened. Blood will flow slowly after decapitation and is unable to spray in a big gush.
As a result, a headless cockroach does not bleed to death. Their blood pressure does not drop to dangerous levels, meaning their necks will eventually cease bleeding and get clotted.
What Finally Kills A Headless Cockroach?
If a cockroach loses its head in some unfortunate accident (usually a predator has bitten it off or a human has swatted it) then it isn’t going to die from bleeding to death or not being able to breathe.
It’s also, surprisingly, not going to die from losing its brain function.
However, without food, it will ultimately perish. Furthermore, before that, it will die of thirst. A headless cockroach has no means to quench its thirst and will perish from dehydration in just over a week.
Lack of Food
Without a head, the cockroach simply can’t eat so death is a certainty, but how long depends on various factors.
It takes them between one and four weeks to die of starvation depending on how large they are. For an average-sized cockroach, it is estimated that they will starve in about two weeks without food.
A cockroach survives without food by living off the fat body stores. The bug begins to feel extremely hungry after about four days, but can go longer depending on its size.
Since cockroaches are cold-blooded animals, their metabolism slows down in colder climates which will increase how long they can go without food. Colder temperatures in your home will slow their metabolism even further which will have them living off their fat stores even longer.
Cockroaches can live up to one month without food in ideal situations, but that typically only happens when they are under very unusual circumstances.
Lack of Water
Cockroaches can’t drink without a mouth so when it comes to water, they are pretty helpless. However, it can still take a few days or weeks to bring their life to an end.
That’s because water loss occurs in three ways:
Evaporation – Warm temperatures and low humidity cause water to evaporate rapidly so cockroaches will dry out faster.
Respiration – The respiratory system uses water to cool the body just like humans, but a headless roach can’t do this.
Excretion – A headless cockroach cannot excrete waste properly and they expel water with their waste which speeds up dehydration
The biggest problem for cockroaches and water is the fact that it needs to be circulated around the body. A headless, or nearly headless roach, doesn’t have a way of doing this so it dies fairly quickly depending on conditions. Once again though, we see that colder temperatures can preserve them for longer periods of time.
The more hydrated cockroaches are before they’re beheaded, the longer they’ll live. Limiting a cockroach’s access to water beforehand will hasten its death. It won’t have as much strength or endurance as it would if it had had access to water.
Another consideration in this gruesome story of the cockroach losing its head, is the fact that predators will easily be able to hunt them down. With no way for the cockroach to detect or avoid the predator, it will not have a quick enough reaction time to scurry away or climb a wall to safety. This means certain and quick death for the cockroach.
There is no consensus on how long a decapitated cockroach can survive without a head. However, based on how long it may endure starvation and dehydration, we may calculate how quickly its death-clock ticks.
All these factors play a part in determining the lifespan of a headless cockroach. If the conditions were right (a cool temperature and not many predators around) this could allow the cockroach to last about a month without the need for their head, as long as they did not get infected with a bacteria or virus, which is probable and would kill them within days.
Can Cockroaches Grow Their Heads Back?
The quick answer is no.
Even if a cockroach manages to escape its predator in one piece, they cannot simply grow a new head when they need it.
Cockroaches can grow back legs, antennae and even the mouth-part (which is called the labium) but not their heads.
The reason for this boils down to simple biology. The head of a cockroach is actually part of its thorax and it’s attached to the abdomen by a joint. This allows for mobility and is how they can wiggle their behinds and run so fast. However, this means that when one part of their body gets lost, all the other parts will get dragged along with it.
A decapitated cockroach cannot survive for very long. It will typically die within a few days or a couple of weeks depending on how much water and food it had access to before being beheaded. The temperature of its environment also plays a factor and some decapitated cockroaches can live for longer periods of time if their predators are scarce.
If you have accidentally decapitated a cockroach in your home, remove all of its carcass as soon as possible – dead cockroaches can attract more to the area. Try some home remedies to get rid of cockroaches rather than swatting or squashing them.