Will Ant Spray Kill Spiders? | Effective Techniques for Pest Control

Written by Thomas Matthews

If you have a spider problem in your home and are thinking about trying an ant spray that you have nearby, you will likely want to know whether it will have any effect on spiders as well. Insecticide sprays are very similar in some aspects but naturally different insects react differently to common toxins.

Will ant spray kill spiders too? Ant spray will usually kill spiders if you spray them directly with it. However, if you apply the spray to the ground or a wall, the residual effect probably won’t be enough to kill them. If you want to consistently kill spiders that enter your home, consider an alternate method like spider traps.

In this article, we will explain why ant spray is not particularly effective against spiders and what you should do instead to keep spiders out of your house. Additionally, we have also listed some common toxins that are used in insecticides and compared their effect. Let’s begin!

How Does Ant Spray Affect Spiders?

Ant spray or other insecticides will kill a spider if the spray particles land on them. However, if you have a colony of spiders in your home, you won’t have much luck using an insecticide against them.  

There are two reasons for that. The first is that you are using an insecticide, but spiders aren’t insects.  

The misconception that spiders are insects is so common that many insecticide products lump them together. For example, Ortho (a popular insecticide company) claims that its spray kills “ants, roaches, spiders, fleas, and other household insects.” However, spiders are not insects, and some of the ingredients in ant sprays don’t affect them.

Although some ingredients in a typical insecticide don’t affect spiders, enough of the active ingredients in insecticides are deadly if the spider makes physical contact with the spray particles. The main problem is getting the spider to make contact with the spray. 

How Does Ant Spray Affect Spiders

Ants will naturally make physical contact with the insecticide, as they keep their bodies close to the ground when they walk. However, spiders have long legs and don’t scrape their abdomens against the ground. Therefore, merely spraying insecticide on the ground probably won’t solve your spider problem. 

Ants also ingest insecticides picked up from the ground when they groom themselves. Because spiders do not groom themselves with their mouths, there is a smaller chance that they will ingest the poison.  

The best way to eliminate a spider with the use of an ant spray is to either spray the spider directly or apply the spray to a crack that a spider uses. However, this can be difficult if you have a lot of spiders in your house, especially spiders that hide in hard-to-reach places.

With all of this in mind, spider traps are a better solution for anyone dealing with a spider problem. These traps will attract and kill the spiders without you having to waste your precious time (we are going to talk more about spider traps later in the article).

How Does Ant Spray Work?

Some ant sprays kill ants by disrupting their physical process, while other insecticides use bacteria, fungi, or viruses to destroy the ants. The most common insecticides affect the insect’s nervous system and others wreak havoc on the oxygen metabolism, water balance, or growth cycle. ‘

Let’s take a deeper look at the most common ways that insecticides work to kill ants, spiders, and other unwanted pests. 

Affect to the Nervous System  

The following toxins such as organophosphates, carbamates, chlorinated hydrocarbons, and pyrethroids all disrupt nerve impulse transmissions, which happen at the synapses (the gaps between one nerve cell and the next). By causing the synapses to be unable to function correctly, these poisons cause convulsions, paralysis, hyperactivity, and uncoordinated movements.

The following table lists the main groups of toxins that affect the nervous system. Use this to identify what type of poisons are being used in your ant spray:

Class of ToxinsExamplesHow They Work
OrganophosphatesChlorpyrifos, malathion Interfere with the function of synapses
CarbamatesCarbaryl, bendiocarb, and propoxurAlso, affect the synapses, but wears off rather quickly.
PyrethroidsPermethrin, cypermethrin, fenvalerate, and cyfluthrinThese synthesized insecticides last longer than the above-mentioned ones.
Chlorinated HydrocarbonsMethoxychlor and dicofolDisrupt how potassium and sodium ions move across the nerve cells’ surface.

Affect to the Respiratory System of Insects

Sprays called insecticidal “soaps” contain chemicals such as potassium salts that interfere with the insect’s breathing. They do this by penetrating the insect’s body.

Once inside, they begin dissolving the cells. The cells that line the insect’s breathing tubes collapse, consequently clogging the tubes. This prevention of breathing will also work on spiders.

Insect Growth Regulators

As insects grow, they molt, shedding their skin in order to grow a new one. In some cases, the molting process also changes the insect’s form, like a caterpillar changing into a chrysalis. Compounds like methoprene and pyriproxyfen disrupt that process by affecting the proper function of the hormones that control growth.

The advantage of Insect Growth Regulators (IGRs) is that since we do not have insect growth hormones, they do not affect humans. However, IGRs don’t affect adult insects and are not made for use on spiders. If your ant spray contains an IGR, you might want to select a different spray for dealing with your spider problem.

Deadly Microbes

Some of them can even contain insect-attacking microorganisms. Virus-based insecticides need to be consumed by the insects in order to harm them. Because they only attack insect cells, microbial insecticides are not considered harmful to humans.

Once the insect has ingested the insecticide, the virus or bacteria goes to work, multiplying themselves so much that the insect’s cells burst. 

Unless you spray microbe-powered insecticides directly on a spider, it won’t be too effective because spiders don’t groom themselves and are unlikely to ingest any spray that gets on their legs.

Spider Traps Are More Effective Than Ant Sprays

If you have more spiders in your house than you are comfortable with, then spider traps are your best option. Most of these traps work by trapping spiders with a sticky compound. Indeed, spider traps are often called sticky traps or glue traps.   

Proper trap placement is essential. Although placing them along baseboards and in dark places is generally good advice, you will have to experiment to find the most effective locations. If a trap hasn’t caught a spider after two days, you should relocate it.    

Once you have found a route that the spiders seem to use, you should place a series of traps on that route. Once the traps catch an insect or two, the spiders will be attracted to them. They will go on the trap to get a meal and become trapped.

The Trapper Insect Trap is an excellent spider trap for money. While it’s technically an insect trapper, it will work just as well for catching spiders.

Trapper Insect Trap (Great for Bed Bugs, Spiders, Cockroaches) - Includes 90 Traps
  • Trapper Insect Trap,bed bug Trap,spider Trap,Cockroach Trap
  • Trapper Monitor & Insect Trap - 30 Boards (90 Traps)

You can get 90 traps relatively cheaply. Being small and inconspicuous means that you can easily place them behind furniture, near windows, or anywhere else that spiders frequently traverse. 

Be careful of traps that contain scents like peanut butter, as they can attract mice and other unwanted rodents. If you want to add some bait to your trap, kill a couple of mosquitos or ants and stick them on the traps.

How to Keep Spiders Out of Your Home?

If you don’t want spiders in your home, the best thing to do is deprive them of food. Seal possible entry points for insects, such as cracks in walls, holes where cables and wires enter your house, doorways, and windows. 

If the spiders find that your home lacks insects to eat, they will either leave to find a better hunting ground or starve to death. Either way, you’ll be rid of them.

List of Sources

Ecological Importance of Ants. Harvard Forest, Harvard University.
Ants in the Home. Colorado State Extension.
How Insecticides Work. New Hampshire Extension.
Don’t Kill That Spider in Your House. Washington Post.

Thomas Matthews
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