How Does Wasp Killer Work? (And the most effective ingredients in wasp killers)

By Landon Easton •  Updated: 03/01/21 •  6 min read

You might not live in an area that has too many wasps, but for some reason, you’ve noticed a surge in the number of wasps around. And since you don’t want to disturb the hornet’s nest, you run to the store, get a wasp spray, back home, and in just one sweeping motion, you’ve pressed the canister’s button, and the wasp drops dead on the ground. Ever stopped to wonder how exactly a wasp killer gets all that power and how the wasps die in seconds, if not minutes?

Wasp killers, whether sprays or dust, are powerful insecticides that combine the neurotoxic powers of the insecticide’s chemicals – pyrethrins, and pyrethroids to paralyze and kill wasps. When the spray killer is used, for example, these chemicals are released, and the powerful blast of the chemicals knocks down the wasps on contact.

How exactly do wasp killers kill wasps?

Wasp killers’ mechanism of action is rather impressive, although it’s very much tied to the chemical ingredients in the insecticide. The best of wasp killers are formulated using pyrethroids and pyrethrins, both neurotoxins that knockdown wasps fast by targeting the insect’s nervous system, affecting how the neurons fire, subsequently causing paralysis and death. In large concentrations, pyrethroids and pyrethrins overwhelm the insect’s nervous system, forcing the insects to drop out of the sky instantly.

These chemicals affect the central and peripheral nervous systems of the wasps. Initially, the chemicals stimulate the nerve cells to fire repetitively, resulting in eventual paralysis. The pyrethroids cause modification of the Na+ channels, holding the nerves open, and impeding the membranes’ potential, hence an abnormal state of hyperexcitability, and subsequently, the knockdown effect. Pyrethrins also kill the wasps in the same manner, with the hyperexcitation of the nerves resulting in the loss of motor coordination for the insects, paralysis, and subsequently, death. All these take place in seconds, which is why the death of wasps after they are hit by the burst of the spray occurs instantly.

Other wasp killers fall into the carbamate and organophosphate categories, and they work by blocking acetylcholinesterase enzyme. In the absence of this enzyme, nerve transmissions are unstoppable, causing whole-body seizures and subsequent knockdown and death.

What ingredients should you look for in wasp killers?

The effectiveness of wasp killers depends on the ingredients used, but the pyrethroids and pyrethrins are the main chemicals that kill wasps.

Under these two broad categories, the active insecticidal ingredients vary, but the most common ones are listed below:

Cypermethrin and Prallethin are both fast-knockdown synthetic pyrethroids that work not just as insecticides but also as anti-feeding agents in larvae. The other active ingredient you can find in wasp killers is Lambda – Cyhalothrin, also a pyrethroid registered as an insecticide by the EPA. You may also find wasp killers formulated with tetramethrin and Phenothrin.

So, if you are looking for the most effective wasp killer or a hornet spray, these would be the ingredients you want to find in the spray. These ingredients give the wasp killers their effectiveness and that fast knockdown effect. You only need to make sure that the amount of spray used will be enough to kill all those wasps and to get rid of the hornet’s nest.

The wasp killers come as sprays/ aerosols, liquids, or powdered forms.

The aerosol sprays, for example, the Ortho Home Defense Hornet & Wasp Killer7 or Raid Wasp & Hornet Sprays are ideal when you need a quick knockdown effect for the wasps, and the best aerosols allow you to spray as far as 15-20ft away. These sprays have an oily base, and though this may cause staining, it sticks to the wasp, causing death on contact.

On the other hand, dust or powdered insecticides like Bayer Tempo 1% Dust are more ideal for targeting void areas, especially if you want to kill any emerging wasps. The dust offers protection of up to 6 months. They also work as neurotoxins as they are formulated with pyrethroids and pyrethrins.

Then you have the other class of wasp killers, the residual liquid insecticide like the Ortho 0220910 Home Defense Insect Killer, which is ideal for pest control and spraying potential future wasp nesting area, helping you control future infestations.

Types of Wasp Killers Ingredients Effectiveness/ Use Distance
Aerosol Sprays Pyrethrins and Pyrethroids Instant / Knockdown 15-20/27ft away
Dust insecticides Pyrethrins and Pyrethroids Kill on contact, protection for 6 months max. Used in voids, Contact with target areas required
Liquid Insecticides Cyfluthrin 1% (pyrethroid) Kill on contact and prevent eggs from maturing Prevention of future infestations. No separation distance needed for use.

How fast do wasp killers work?

Often, the wasp killers will knockdown and kill the wasps instantly, with the last wasps expected to be dead in 24 hours. So, if you had a wasp nest in the garage, it would be safe to go back in after 24 hours. However, in the event of wasp eggs, the wasp killers have a long residual effect of up to 6 months in some cases. So, you won’t have to worry about a re-infestation too soon after the initial treatment.

How far away should you stand from the nest to spray the wasps?

If you are dealing with an entire colony and not just one lone wasp, you’d want to stand some distance away to avoid being stung by the wasps. Since the insecticide sprays kill on contact but you are also targeting aggressive insects, you’d want to stand about 20ft (maximum of 27ft) away. The long-range allows you to reach the nest without using a ladder to reach the nests on the eaves of your home. Just keep in mind that the further you are, the harder it gets to target and kill the wasps. So, stick to a distance of 27ft or less (other companies recommend a range of 15 – 20ft) for a successful approach. Once set, keep the nozzle depressed for a while to coat the entire nest and to disable any wasps that might have been up for a retaliatory attack. This means that a few spurts won’t be enough.


Wasp killers kill wasps by targeting the insects’ nervous systems, altering nerve function and killing the insects. The insecticides used coat the insects, and even if they don’t die instantly, they eventually die because they’ve had contact with the neurotoxins.


Should I use a ladder to reach the nest?

We wouldn’t recommend the use of a ladder because you could easily fall off it if the wasps attack. But in cases where the nests are too far off the ground or hard to spot, you may need the ladder. Just make sure to keep some safe distance between you and the wasps/ nest.

What is the best time to spray into wasp nests?

You should always spray wasp nests at night when the wasps are less aggressive and also when they are all home. Wasps

Landon Easton

Landon is a veteran in the Pest Control industry, with over 15 years of experience and has helped thousands of homeowners. He started Your Pest Guide in 2020 as a way to help spread his knowledge to the general public, so they can get rid of all of their creepy-crawlies in their homes without spending an arm and a leg.