Is Bug Spray Painful for Insects? (Quick Facts)

When we see insects in our home, our basic instinct is to purchase a bug spray and kill them. It may not be just, but it’s only evolutionary to find the easiest way to eliminate nuisances.

However, many people pose completely reasonable ethical questions on the use of these sprays. It may be okay for us to use them, but that’s as long as they’re not painful for the insects. For this reason, many people wonder, are bug sprays painful for insects?

Some scientists believe that bug spray may be painful for insects since they have nerve endings just like humans. However, most insects don’t have something you’d call a brain, which leads to a lack of emotions. That’s why most scientists don’t believe bugs feel pain.

Close up of unknown woman using poisonous spray to kill cockroach at home

Generally spoken it’s unclear just how difficult it is for bug spray to kill insects and whether it does actually pain the animal. Today, we’ll be taking a closer look at insects and answering a few questions that you might have. In today’s article, we’ll be finding answers for questions like: what happens if you spray a bug with a bug spray, do insects feel pain when sprayed, is it inhumane to spray bugs, and how long does it take bug spray to kill?

Let’s get started!

What Happens If You Spray a Bug with a Bug Spray?

Firstly, bug sprays contain chemicals that paralyze bugs instantly, so the first thing that’s going to happen when you spray a bug is paralysis. It doesn’t matter whether you spray the insect directly, or you spray an area where the insect will walk – the spray will take effect immediately and paralyze the bug.  This is known as the knockdown effect.

After the bug’s stopped moving, pyrethrins or pyrethroids will take effect to kill the bug. Most of these sprays rely on one of these chemicals as their active ingredients, and these are ingredients that really kill the bugs. Pyrethrins are compounds found in chrysanthemum flowers, pyrethroids are actually synthetic copies of pyrethrins.

Bug sprays are actually mild chemical weapons.

Do Insects Feel Pain When Sprayed?

As we’ve already said, this is a grey area for science. There are basically two schools of thought: insects must feel pain just like humans do because they have nerves and nerve endingsOpens in a new tab., and insects don’t have emotions, so they don’t feel any painOpens in a new tab.. There are also arguments to both sides.

The argument for the latter is based on the definition of pain and the conclusion it brings with it.

Pain is a subjective experience connected with negative emotions.

So the real question is whether insects have emotions that enable such a sensation. In the way we understand them, such feelings require a complex interaction and interpretation of stimuli, which is only possible in a well-functioning brain.

Scientists agree that the small size of insect brains does not allow for complex functioning. There is too little cooperation between the specific brain areas and also not sufficient exchange between the parts of the brain.

Observing injured insects you might be wondering why they nevertheless squirm around and fight for their lives. And indeed that’s exactly what they do. Like every animal on this planet, insects are capable to sense damage occurring to their body (called nociceptionOpens in a new tab.).

This reaction grants a substantial evolutionary advantage for survival but is not pain in the sense of our seen definition.

Bugs feel damage to their body, but no pain (as an emotion)

The other point of view starts exactly at this point and is doubting the definition is applicable in that way. They say it isn’t important how the sensory input is valued. Beeing a negative sensation is sufficient to being called ‘pain’. How else would you describe the impression of being killed?

In the end it comes down to a somehow philosophical question about emotions and where they begin. The vast majority of scientist agree to the opinion that insects feel something is wrong, but no pain like we do.

Is It Inhumane to Kill Bugs?

We seem to jump to the solution of killing a bug as soon as we see one, especially when we see mosquitoes and spiders. We also seem to be much more forgiving to dogs, cats, and birds.

Firstly, it should be noted that cats and dogs aren’t likely to bite you and suck on your blood, and they’re not annoying. If you look at it like that – it’s self-defense. There are many insects out there who are knowingly or unknowingly harming you, so by that (quite simple) logic, it’s not wrong to kill them.

We’re also sorry to break your heart, but you are probably unknowingly killing insects all the time (especially when you’re driving).

However, there may be instances when it’s completely inhumane to kill bugs, as you’re not doing it for any good reason.

For example, if you’re living in a first-world country, your house spider is likely not dangerous at all. If anything, it’ll keep your house clear of flies and mosquitoes. This, after all, depends on your personal beliefs.

How Long Does Bug Spray Take to Kill?

There’s no specific answer to this question, as it largely depends on the size of the insect that’s being killed and the amount of insecticide which is applied.

Larger insects, like the huntsman spider, are going to take much longer to kill. The amount of insecticide entering the body of the bug needs to be much higher than in smaller insects. Furthermore, it needs to enter the insect and start to react with the organs to fulfill its deadly task.

However, if you’re spraying on a bunch of flies or mosquitoes, you’re likely going to kill them much faster. Also, most people tend to spray an insect and then just smack the insect or crush it as soon as it’s paralyzed.


Martin is the head of and he loves to share his research and experience with you.

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