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How Do Cockroaches Die When Sprayed?

If you’ve ever had to use roach spray, you may wonder exactly how it kills a roach. 

How cockroaches die when sprayed depends on the type of spray you use. However, almost all roach sprays affect the nervous system by disrupting its normal functions. Other insecticides work differently, even though poisons that affect the nervous system are the most common. 

How Do Roach Sprays Kill Cockroaches?

A person's hand spraying on a cockroach with a white background.

The way that a roach spray kills a cockroach depends on its active ingredients. 

However, most roach sprays use either pyrethrin or carbamates as their primary active ingredient. 

Thus, these are the two chemicals that I will explain below. 

How Does Pyrethrin Kill Roaches?

Pyrethrin is one of the most popular ingredients in bug sprays since it kills cockroaches, bed bugs, ants, mosquitoes, flies, fleas, and more. 

This toxic compound actually comes from the chrysanthemum plant, which you can find in gardens worldwide. 

Pyrethrin kills insects by targeting their nervous systems, as many other insecticides do. 

In short, pyrethrin overexcites the nervous system to the point that the neurons are firing so much that they cause paralysis and eventually death. 

More specifically, pyrethrin disturbs the movement of sodium and potassium across the neuron membrane. 

You see, neurons send electrical signals through protein channels in this membrane, which (to put this more simply) allow muscles to move. 

This function is necessary for normal movement in all animals. 

However, pyrethrin disrupts this neuron membrane by keeping it open. 

Thus, the neurons fire continuously, causing the muscles to move too much. 

Constant muscle contractions eventually lead to paralysis. 

Then, paralysis leads to death. 

How Do Carbamates Kill Roaches?

Like pyrethrins, carbamates also kill insects by overexciting the nervous system. 

However, they do so in a different way. 

Basically, every animal has something called acetylcholine in their bodies. 

And acetylcholine is vital because it allows neurons to communicate with each other. 

But, having acetylcholine in the body for too long causes problems because it will tell the neurons to keep firing. 

Thus, the body needs something to break it down, and that is where cholinesterase comes into play. 

Cholinesterase is an enzyme that breaks down acetylcholine before it can make the nerves fire again. 

Yet, carbamate affects cholinesterase, blocking it from breaking down acetylcholine. 

Therefore, the acetylcholine stays in the insect’s system and forces the nerves to continue to fire. 

In the body, this causes muscle spasms, which affect major organs, such as the heart. 

After severe damage has occurred to the heart and other organs, the insect’s body shuts down, and it dies. 

How Do Roach Powders Kill Cockroaches?

There are two main types of roach powders on the market, and I will discuss both of them and their effects below. 

How Does Boric Acid Kill Roaches?

Boric acid, usually sold as a powder, kills insects by affecting their nervous system and stomach. 

It can also leave scratches on the exterior of arthropods, such as roaches, spiders, and ticks, which can disrupt the way they hold water. 

How Does Diatomaceous Earth Kill Roaches?

Diatomaceous Earth (DE) is a white powder made of phytoplankton fossils, and it kills roaches, fleas, and bed bugs as long as it stays dry. 

DE works differently than most other pesticides because it does not directly affect the inside of the insect. 

In fact, DE is not even poisonous. 

Instead of poisoning the bug, DE dries out the oils and fats on an insect’s exoskeleton, which causes them to dehydrate quickly. 

How Do Roach Bait Stations Kill Roaches?

A dead cockroach in front of a bait station on a white background.

Roach bait stations kill cockroaches by luring them to poisonous food. 

Basically, how it works is that the bait station contains food that roaches like. 

However, this food (bait) also has a delayed poison. 

It has a delayed poison instead of a fast-acting one because it allows the roach to return to its nest before it kills it. 

Then, when the roaches in the nest see the dead cockroach, they will eat it, which will spread the poison to other members of the colony. 

What Type of Poisons Do Bait Stations Use?

Most commonly, bait stations use boric acid, fipronil, indoxacarb, or hydramythelnon, as active ingredients. 

Fipronil kills roaches by affecting the central nervous system, just like pyrethrin and carbamates. 

Hydramythelnon, on the other hand, slows down the insect’s metabolism to the point where they no longer have the energy to move around. 

Meanwhile, indoxacarb blocks the sodium channels in cells so that the bug dehydrates. 

And boric acid, of course, harms the nervous system and stomach of the insects it kills. 

How Does Gel Bait Kill Roaches?

Gel bait works in almost the same way as bait stations since the roach eats the toxic bait and brings it back to its nest, where the other cockroaches will eat the body and become poisoned. 

What Types of Poisons Do Gel Baits Use?

Just like in bait stations, the most common ingredients in gel baits are hydramethylnon, fipronil, and indoxacarb. 

How Do Roach Motels Kill Cockroaches?

A cockroach caught on a sticky strip.

Roach motels, also called adhesive traps, do not contain a pesticide. 

Rather, they house a sticky strip that traps roaches as they walk inside them. 

Later, when the trap becomes full, you can just throw it in the trash, and the trapped roaches will die of dehydration. 

Why Do Roaches Die When You Step on Them?

Well, first off, let me say that roaches do not always die when you step on them. 

Roaches will only die from getting smashed if you pop their torsos. 

Because if you pop a roach’s torso, its blood will ooze out, so it will not be able to carry essential nutrients around its body. 

You will also destroy the insect’s tracheal system, which is what allows it to breathe. 

Additionally, you may smash some of its vital organs, like its heart. 

Will Roach Insecticides Always Kill Cockroaches?

Photo of different brands of cockroach insecticides being sold in a store.

Roach insecticides will not always kill cockroaches because some roaches have developed an immunity to them. 

Since many of the insecticides we use today have been around for decades, or sometimes longer, some roaches have evolved to be immune to them. 

Do Roaches Feel Pain?

Talking about all the ways that insecticides and other methods kill roaches can get a bit disturbing. 

So, many people start to wonder, do roaches feel pain?

And, of course, there is no absolute answer because we can not actually feel what a roach does. 

However, researchers are pretty sure that roaches do not feel pain because they do not possess the pain receptors that humans and many other animals have. 

Despite this, roaches probably do sense when they are injured, and they might feel uncomfortable about it. 

But, it is highly doubtful that roaches feel emotions as we do since their brains are so primitive. 

Thus, you can rest assured knowing that a dying cockroach doesn’t feel devastated at the loss of its life. 


For the most part, cockroach sprays use either pyrethrin or carbamates to kill roaches. 

Both of these poisons work on the nervous system of roaches, just in different ways. 

Other methods of killing roaches work differently, though, with some affecting the stomach and others causing dehydration.