Why Are Dead Cockroaches Always on Their Back?

When a cockroach is found on its back, most people assume that it is dead. It will be unable to move or react, so it seems like absolute confirmation that it’s deceased. However, roaches found on their bellies can also be dead, and those on their backs may be alive. This seems really confusing, until you understand the true cause of death.

Dead cockroaches don’t always lie on their back. In fact, this only happens when they’re poisoned with insecticides. The neurotoxic chemicals work to compromise a roach’s nervous system, so it loses control of its muscles. The muscles then spasm violently as the poison takes effect, and the roach flips onto its back. Because roaches have a high center of gravity, they are unable to flip themselves upright.

At this point, the cockroach is still not dead. It’s simply paralyzed and will be forced to lie there until it starves or dehydrates. If roaches are not poisoned with a specific type of chemical, they hardly ever die on their backs. Instead, they will die on their bellies, sides, or whatever position they were left in by the fatal injury or infection. In the wild, roaches that fall onto their backs will also use their surroundings to get back on their feet.  

Why Are Cockroaches Upside Down When They Die?

In the home, most roaches are found dead on their backs. This is not because they have a natural instinct to flip over when death approaches. Instead, it’s caused by the poison you’ve exposed them to.

Certain insecticides work by targeting a cockroach’s nervous system. Once it’s compromised, they will be unable to properly control their muscles. This creates severe muscle tremors that can flip the insect onto its back.

Cockroaches have a high center of gravity. They carry most of their weight on their backs. As such, they will be pinned down much like a turtle. If they cannot reach a nearby object to gain leverage, they will be unable to flip back over.

Depending on the poison, they may also be paralyzed for several hours or days. This can prevent them from reaching out and tipping back over.

In this state, roaches are left to starve or die of thirst. They will be unable to move, forage, or defend themselves from predators. They die in this position, not because of a natural instinct or cause. Instead, it’s just where the poison left them.

why are cockroaches upside down when they die?

How Do Insecticides Target The Nervous System?

Neurotoxins are chemicals that affect the nervous system by stimulating neurons. Some of these neurons are located in ion channels, which are a type of protein. They regulate the voltage between cells in a cell membrane.

When these neurons are stimulated, they send electrical signals through the nerve fiber. This releases a wave of neurotransmitters. Depending on the way the neurons are stimulated, the neurotransmitters send signals to:

  • Muscle cells
  • Nerve cells
  • Gland cells

For example, if a roach wants to move its leg, its brain sends a message to the ion channels in the cell membrane. These release neurotransmitters that give the message to the muscle cells. Once the muscle cells are notified, the cockroach is able to use its leg muscles to move as it pleases. All of this happens in just a few microseconds.

All that changes when cockroaches are exposed to insecticides. The neurotoxin breaks down the most important enzyme used in neurotransmission: acetylcholine (ACh).

How Insecticides Make Cockroaches Flip Upside Down

Acetylcholine is known as the leader of the neurotransmitters. It plays a big part in unconscious movements, such as:

  • Dilating blood vessels
  • Slowing down the heart rate
  • Stimulating responses to smooth muscles
  • Inhibiting stimulation in the muscles

When neurotoxins break down acetylcholine, it multiplies it at the same time. According to the Journal of Insect Physiology, insecticides increase ACh content in the thorax by 300% in cockroaches. The excess amount of acetylcholine is what causes muscle spasms.

With an excess of acetylcholine, the neurotransmitters overstimulate the muscle cells. Instead of moving an inch, the cockroach shakes its entire body until it flips over.

Are Upside Down Cockroaches Alive?

Most insecticides claim to kill cockroaches, but the truth is, they aren’t always successful. The upside-down roaches you encounter are still alive. If they don’t move when you pick them up, it’s because they’re paralyzed.

However, this effect does wear off eventually. Depending on the strength of the poison and the immune system of the roach, it may take between a few hours and an entire week.

Quick recovery times are credited to how adaptable roaches are. According to the journal Scientific Reports, cockroaches have even developed a cross-resistance to insecticides.

No matter the case, roaches that are left alone will later regain their ability to move. However, the weight of their own top-heavy back will pin them down. If you were to dangle a tissue above the roach, it would grab it. Using the object as leverage, its strong legs would help it flip back over.

Do Cockroaches Die Upside Down in Nature?

In nature, it’s very rare for a cockroach to die on its back. Insecticides are created by pairing several different chemicals together, many of them synthetic. Roaches never encounter them out in the wild.

Even when insecticide is sprayed outside, cockroaches have plenty of ways to right themselves. When the paralyzing effects of the toxin wear off, roaches can easily grab onto twigs, leaves, and branches. Some may even get flipped onto their bellies with a strong gust of wind.

This is true no matter how roaches fall onto their back. For example, cockroaches don’t have iron grips and can fall while climbing. Likewise, they are unable to control themselves accurately when flying. They may fall onto their backs after their wings give out or due to a bad landing.

Even if a cockroach is unable to right itself after falling on its back, it’s more likely to die from getting eaten by predators. That will leave it in the animal’s stomach, not on its back.

Why Do Cockroaches Come Out to Die on Their Backs?

After spraying insecticide, it may seem as though half the roach population in your home decided to come out just to die on their backs. However, this isn’t a type of funeral ritual or a natural instinct. Instead, we can once again thank pesticides for this phenomenon.

The roaches were likely affected by slow-acting neurotoxins. Since that didn’t kill or paralyze them right away, the bugs continued with their normal lives. While they would usually retreat back to their nests, the poison may have kicked in mid-route.

This caused the roaches to fall over onto their backs in plain sight. When several members of the colony are affected in this way, it can seem like they came out just to die on their back.

Do Poisoned Roaches Still Look For Food?

Cockroaches navigate areas by setting up routes. These routes are used by all the roaches in the area because they are well-established and safe. Even if you place an obstacle in the middle of a cockroach route, it will climb over it or go around until it can follow the trail again.

Cockroaches are very loyal to these routes. They will use them to travel around the house until they are no longer deemed safe. That doesn’t change when a roach is exposed to poison. If the neurotoxins are slow-acting, its nervous system will be attacked over the course of a few hours, instead of right away.

Unlike us, when cockroaches feel sick, they don’t think about going home. Instead, they continue navigating the routes after being exposed to poison. As the roaches scavenge for food, they begin to lose control of their muscles. Eventually, they are unable to get back to their harborage.

If you spot cockroaches out on their backs after spraying insecticide, take note of their location. They might have died on or near a route that other cockroaches use. You can use that information to track down the opening of their nest for further extermination.

why do cockroaches die belly up?

Why Do Cockroaches Die Belly Up?

Not all insecticides are made to compromise a roach’s nervous system. Depending on the active ingredient, it may also affect its ability to digest food or absorb water. Some are fast-acting, paralyzing the roach within seconds after contact. Others rely on the bug spreading that poison to other members of the colony over time.

The effectiveness of the poison is also dependent on the toxicity of the active ingredient. Since roaches can be resistant to certain poisons, it’s important to understand what sprays, bait, and traps we need to eradicate them.

Active ingredientToxicity levelNeurotoxin?
N-Methyl carbamatesHighYes
OrganophosphatesHighYes
PyrethroidsModerateYes
NeonicotinoidsModerateYes
Insect Growth RegulatorsLowNo
IndoxacarbHighNo
HydramethylnonLowNo
FipronilModerateYes
Diatomaceous EarthModerateNo
BoratesLowNo
AvermectinHighYes

When a roach is exposed to neurotoxin, only then will it die upside down. If it encounters a poison that doesn’t cause muscle spasms, it dies face down.

As such, insecticides that target the nervous system are preferred. This ensures the roach is less likely to survive the encounter, even if resistant to the poison. It will be trapped on its back and unable to flip back over. This allows you to dispose of the roach however you please, or wait for it to die.

Cockroaches don’t always die on their backs. They will die in whatever position their injury, infection, or lethal dose puts them in. They may stay alive for several days, or even weeks.