Why Are Dead Cockroaches Always on Their Back?

Dead Cockroach on his back on the floor

Cockroaches do spread a loathsome vibe wherever they are. But their acrobatic move of suddenly lying on their back is quite fascinating, especially when they violently move their legs.

A cockroach lying on its back means it will not stand on its legs again unless someone helps them or they miraculously find support and right themselves. But why do cockroaches die on their backs?

This post will give you the answers related to cockroaches lying on their backs while dying. So let’s dive into it.

Why Do You Find Dead Cockroaches on Their Back?

Cockroaches are on their back while dying because of the poisonous effect of the insecticide. The chemicals in these insecticides compromise the roaches’ nervous system. Other than spraying an insecticide, you might never see a roach lying on its back.

There are several neurotoxins present in an insecticide. A neurotoxin targets the nervous system of roaches and causes muscle spasms. The common neurotoxin chemicals for these bugs are:

Once the roaches inhale or taste the deadly chemical, you will see them taking an instant flip and lying on their back.

How Do Neurotoxins Attack Cockroaches’ Nervous System?

Neurotoxins, or nerve agents, produce and break down several enzymes inside a cockroach and damage the neurons. The roaches’ nervous system uses neurotransmitters to communicate with the brain and the whole body.

The axon terminal is the part of the neuron where neurotransmitters are located.

For example, when a roach decides to move its legs, the brain sends a message to the legs to move. The respective cell membrane releases neurotransmitters that carry the message.

When they deliver the movement signal to the muscle cells, only then can a roach move its legs. However, the neurotoxins inhibit this natural muscular movement and attack the enzymes responsible for:

  • Expanding/contracting blood vessels
  • Controlling pulse rate
  • Responding to muscular movements

When these natural enzymes face such chemical reactions, they respond violently and cause muscle cramps in roaches.

Insecticides also cause other health issues to cockroaches. So flipping on its back can be a sign that you have successfully penetrated the bug’s exoskeleton.

Are Upside Down Cockroaches Really Dead?

Upside-down cockroaches are usually dead, but that’s not always the case. The nature of the insecticide you use matters too.

Some chemicals, like Pyrethroids, impair the nervous system of the pests, making them paralyzed. It’s a common compound found in insecticides and performs well against the army of cockroaches.

A paralyzed roach might look dead, but it might be playing dead. The chemical compound directly hits its neural activity, making it unable to move. So the last movement you will witness is it turning upside down.

Of course, being paralyzed and dead are two different things. A paralyzed roach doesn’t die from the insecticide, but due to:

  • Lack of Food. A paralyzed cockroach can’t roam around in your kitchen and fulfill its nutritional requirements. Although cockroaches can live for months without food as they are cold-blooded, they die of thirst or become prey to other insects.
  • No Water. Water is the source of life for cockroaches. If they don’t get water for a week, they die of thirst. They can even live without a head on their bodies.
  • Becoming Prey. A paralyzed cockroach is the easiest meal for lizards, rats, and geckos. If you find remains of roaches without the corpses, know that other pests are living in your house looking for food.

Do Cockroaches Only Turn Upside Down Because of Insecticides?

Cockroaches turn upside down due to insecticides most of the time. But you may also see them flipping when they are close to a flame. When roaches come in contact with flame, they instantly turn upside down and start moving their legs wildly.

That unintentional burning also proved that cockroaches are not immune to fire.

But that doesn’t mean killing cockroaches with fire is a recommended way. It’s dangerous because there’s a high chance you end up blowing your house.

Do Cockroaches Accidentally Flip?

Cockroaches sometimes accidentally turn upside down without any human intervention. That’s because of their own mistake, or it’s just not their day.

The roaches’ abdomen is the heaviest part which gets most of the gravitational pull. So when you find a roach who failed an attempt to take the leap of faith, know that it’s not intoxicated and is alive.


Do Insecticides Turn a Roach Upside Down?

Yes, insecticides turn a roach upside down by attacking its central nervous system. As a result, the pest’s muscular system stops giving a normal response to the brain’s message and causes muscle spasms. The bug becomes frozen or paralyzed for a long time, waiting for its death.

How Long Does a Roach Live on Its Back?

A roach lives on its back as long its belly has enough food and water. After that, it will die due to thirst in a week, starvation in 3-4 months, or some other pest killing it.

Why Does an Upside Down Roach Move?

An upside-down roach moves because its nervous system doesn’t stop working. Instead, it’s a muscle spasm due to the aggressive reaction of the neurotoxins present in the insecticide. When these spasms go away, they may return to their original position.

Does Every Poison Make a Cockroach Die Upside Down?

No, every poison doesn’t make a cockroach die upside down. Instead, it depends on the chemical compound present in the insecticide. Some chemicals enforce muscle spasms and paralysis, while some rip apart the internal organs of the cockroaches.


Cockroaches are tiny pests with their abdomens weighing the heaviest. So they can’t get up again when they turn upside down due to insecticide or some other reason. That’s mostly the case when you spray insecticides on them.

Roaches go into a state of shock when they are exposed to danger. It makes them frozen and paralyzed for a long time, until they get their senses back. However, if you have sprayed strong insecticide on these bugs, they may:

  • Starve to death
  • Die of thirst
  • Get eaten by predators