Does Boric Acid Really Kill Roaches?

Boric acid is an inorganic common household product that is a popular natural pest control treatment used to try and kill cockroaches.  However, is boric acid really effective and the best option to control roaches? And is it safe to apply in your home?

In this post, we’ll answer these questions and many others.  

Written by: A O’Neill, Licensed Pest Management Professional

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What is Boric Acid?

Boric acid is a powder formed by combining boron and water.  It was used as an inorganic insecticide long before the products used in the pest control industry today were developed. Boric acid is now available in powder/dust and gel forms. It is also an ingredient in many pesticides used to control insects such as cockroaches.

Why Does Boric Acid Kill Roaches?

As boric acid is positively charged it sticks to the cockroach when the insect crawls through the dust/powder and kills by ingestion and absorption.

The roach will return to its harborage and ingest the powder when it cleans itself. The powder is toxic to roaches so it disrupts the stomach and affects the nervous system, and is also absorbed through the cuticle wax causing dehydration and death.  

When the roach dies, it is eaten by other roaches that will also be poisoned and die.

How Long Does It Take for Boric Acid to Work on Roaches?

Since boric acid is a slow-acting insecticide, it may take up to three days to kill a roach; and seven days or more to significantly affect an infestation.[1] 

One of the downsides to using boric acid is that it does not impact the cockroach eggs or unborn nymphs. However, once the newborn nymphs walk through the powder, they’re exposed to it and will die after ingesting it. 

Is Boric Acid Safe to Use?

The acute toxicity of boric acid to humans is considered moderate. It can cause problems if accidentally ingested and can be irritating when inhaled.[2]

Boric acid can be harmful, especially if not used correctly, so always read the label instructions thoroughly and wear proper PPE such as a mask and gloves.

It should never be used on kitchen countertops or anywhere else you prepare food; or applied where children or pets might come into contact with it.  Keep this product stored high up, so it’s out of reach.

Boric acid and pesticides containing this substance are also toxic to indoor and outdoor plants and will cause them to dry out.  Therefore, it should not be put in plant pots in the home or used outside to control roaches.  

How to Use Boric Acid for Roaches

Boric acid is non-repellent and, as you know, kills roaches by oral ingestion and contact. The dust remains effective for a long time if it stays dry but is ineffective if it gets wet.

Most insecticide dust containing boric acid will already come in a bottle with a ready-to-use applicator. 

When using only boric acid, the best way to apply it is with a ‘bellows’ hand duster, so the powder is applied as finely as possible. 

Roaches will not try and crawl through thick layers of dust or powder, so the trick is to apply it so it is hardly noticeable in harborage and common areas where they crawl, such as:  

  • In corners where the floor and wall meet behind the refrigerator (a common area where you’ll find German roaches), dishwasher, and stove. 
  • On top of cabinets and in any cracks on the corners. 
  • Kitchen and bathroom wall and cabinet voids.
  • In gaps around plumbing and where pipes enter walls.
Picture of cockroach nymphs and adults
Picture of German cockroach nymphs and adults in kitchen cabinet

Where Can I Buy Boric Acid?

You can purchase boric acid and the hand duster at many retail stores, including hardware stores, pet supply stores, grocery stores, pharmacies, and online retailers such as Amazon.  Make sure it is labeled as suitable for cockroach control.

Is Boric Acid Good for Roaches?

Boric acid is a common household insecticide that has been used as a natural remedy to kill cockroaches for decades. It’s effective and non-repellent, but just using boric acid or insecticides of any kind will not get rid of an entire infestation on its own.

Controlling cockroaches is best achieved with the use of insecticides coupled with good sanitation and the removal of harborages. In other words, you want to remove what attracts cockroaches such as food and water sources, and make sure they cannot come back into your home again.

Although using boric acid may work for a while, it will not get to the root of the problem. Whenever you find cockroaches in your home, it is best to call in a pest control professional. Alternatively, follow these tips on how to get rid of cockroaches yourself that explain how gel baits and sticky traps are more effective at killing and monitoring cockroaches than other methods.

[1] http://ipm.ucanr.edu/PMG/PESTNOTES/pn7467.html

[2] https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-011001_1-Sep-93.pdf