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How to Know if Roaches are in walls? [Do THIS First!]

Two sites are the hot spot of cockroach infestation inside the house, electric appliances such as fridges and microwave ovens, and cracks and crevices in walls. No matter how hard you try, if you fail to exterminate roaches from these areas, you will never succeed in getting rid of roaches completely. Instead, they will keep reappearing after some time and become a bane of your existence.

To know if roaches are in walls,

  1. Place your ear on the wall and tap it with an object such as a spoon. You will immediately start to hear a subtle buzz called cockroach’s noise.
  2. Or drill a small hole inside the wall and spray a small quantity of insecticide spray; cockroaches will immediately panic and move out of the walls from cracks and crevices.
  3. Physical signs such as cockroach smell from their droppings, smear marks, desquamated exoskeleton, and pieces of cockroach body around the holes in walls or cracks also help you know if roaches are in walls.

Due to the massive price hikes in recent years, people in the US have been moving from concrete construction to houses with wood frames, plywood, and sheetrock construction materials. Unfortunately, these construction material favors roach to hide between the spaces inside the walls. Therefore, to get rid of cockroaches completely, you must first know if roaches are in walls or not and then exterminate them accordingly. I will be sharing my personal experience with this in the blog below.

Tired of cockroaches? Invest in only these products and follow the guide to eliminate roaches!

Use these products, and you will be roach free in less than a week.

1. Advion Cockroach Gel Bait (Review)
2. Gentrol IGR Point Source (Review)

Other Products to try:

1. Combat Roach Traps (Easy than gel baits)
2. Hot Shot Foggers (To kill in masses – 95%)
3. Pet Safe Killers (Uses Essential Oils)
4. Ortho Defence Outdoor Roach Killer (Prevent Roaches)

Methods to know if Cockroaches are in walls

Cockroaches do not like cold and, at the same time, can not hibernate. So, instead, they hide in basements, sewerage holes, and heat-emitting electronic circuits to avoid heat loss.

Similarly, cockroaches hide deep inside walls because of the excellent insulation. Cockroaches even feed on insulating foam and are known to nest there. The problem with roaches hiding in walls is that it’s difficult to know where they are, and getting rid of them is tricky.

However, despite these shortcomings, you can quickly know if roaches are in walls by using any of the following methods,

Method 1: Tapping the wall

If you are an excellent listener, then this method is for you. For example, you can quickly know if roaches are living in the wall with the help of listening to the cockroach noises. Cockroaches, when resting, produce very soft and subtle sounds that are difficult to hear.

However, when they are disturbed, the intensity of cockroach noise suddenly increases. Therefore, if you keep your one ear on the wall and tap the wall with a hard object like a spoon, you will hear a sudden increase in sound if roaches are living in walls.

I have written a complete article on Do Roaches Make Noise? Please read it.

Method 2: Using Insecticide Spray

It’s a universal fact that once you spray an insecticide on insects, including roaches, they start to run desperately, and the area floods with them. So this can be used to our advantage to know if there are roaches in the wall.

All you need to do is drill a hole in the wall, and in case there are cracks and crevices, you do not need to drill a hole. Next, you need to insert the nozzle of insecticide spray into the hole or crack and spray for a few seconds.

If there are roaches in walls, they will immediately run out desperately for their life. This will let you know if the walls are infested or not.

Note: You need to buy an insecticide spray with a nozzle, or it will be difficult to spray inside the wall. Moreover, this method works for wood walls, not concrete.

Method 3: Looking for the Signs to know if roaches are in walls

If none of the methods mentioned above works for you, do not worry. Instead, you can also know if cockroaches are living inside walls by looking for following signs around the cracks and crevices of walls,

1. Cockroach smear marks on the walls

Cockroach smear marks are long streaks of black to dark brown color on walls that have high humidity. These usually appear in damp basement and bathroom walls. Cockroach smear marks are liquified roach poop marks.

Cockroach smear marks provide an excellent clue to infestation inside the wall. All you need to do is study this article: Cockroach Smear Marks: How to Identify? to know more about it.

2. Cockroach Droppings

Cockroach droppings are small black dots like dust or black pepper. They appear around the opening of the walls and indicate an infestation.

3. Cockroach Products

Desqumated exoskeleton, body parts of dead roaches, and eggshells all indicate that cockroaches are living inside the walls. Cockroach products are also present at cockroach nests.

4. Cockroach smell

All these disgusting signs mentioned above have a peculiar musty urine-like smell. If you put your nose close to a crack in the wall, you will easily smell this.

How to get rid of roaches in the walls?

Before you get rid of roaches in the walls, you must work on preventing cockroaches from entering the walls and establishing their colony; following these preventive measures,

  1. Seal all cracks and crevices with masking tape
  2. Fix any leaking pipes and drains inside and near to walls
  3. Use natural roach repellents or mothballs to keep roaches at bay
  4. Do not litter or leave food outside
  5. Cover garbage bins properly
  6. Use IGR spray to keep young roaches from maturing into adult bugs

Next, you must Get rid of roaches in the walls. It is easy and fun. All you need to do is follow any of the Methods,

Method 1: Using Gel Baits

Gel baits effectively kill roaches both inside and out of the walls. All you need to do is apply small quantities of gel bait near and around the walls’ openings, cracks, and crevices and wait for a few days.

Cockroaches eat the gel bait, distribute it among peers, and die inside the wall.

Method 2: Using Insecticide Spray

Insecticide spray has the advantage of deep penetration and instant action against roaches. All you need to do is apply the nozzle, put it inside the wall, and keep spraying for some time. Next, close the room and ventilate it after 15 minutes.

Method 3: Using Traps

Traps are mess-free but slow at killing roaches. Please set multiple traps across openings in walls and wait for a few days to see the results.

Method 4: Using Diatomaceous Earth or Boric Acid

Diatomaceous earth and boric acid effectively kill roaches living inside the wall. Use an air duster that comes with this package of diatomaceous earth to blow them inside the wall. Next, all you have to do is to wait.

Please read these articles if needed,

Roaches on wall; Identification and Getting Rid

Roaches on walls not only look disgusting and filthy but can also cause problems for you. For example, when you prepare food in the kitchen, a cockroach crawling on the wall or roof might fall inside the food and contaminate it. This is because cockroaches cannot endure intense heat above 115 degrees Fahrenheit.

This is the main reason why you sometimes find a cockroach in your food. Therefore you must not allow cockroaches on walls and immediately kill them.


Roaches inside the walls are why we often fail to exterminate them. Therefore, it’s essential to know if your walls are infested with cockroaches or not. Once you know, exterminating them will solve your problem at once.

Additional Read!