Does Leaving the Lights On Deter Cockroaches?

by Derrick | Last Updated: July 2, 2021

Cockroaches have a long history of being depicted as one of the scariest pests you can encounter. An article by BBC notes that cockroaches are the insect we are “programmed to fear.” Television and old tales have long shown us that light will cause cockroaches to scatter. If that is true, leaving the lights on at all times will deter cockroaches, right?

Cockroaches are nocturnal and avoid both natural and artificial light. If you leave lights on or have natural light sources, it is unlikely to see cockroaches scurrying around your house as they work to avoid the light. However, this does not entirely deter cockroaches from invading your space.

The rest of this article will explain different cockroaches, identify their signs and behaviors, and explore preventative measures to keep them away from your home, including extermination. 

Types of Cockroaches

The Smithsonian Magazine published an article that spoke of 4,500 different species of cockroaches living throughout the world. While that number is incredibly daunting, only about 30 of those are classified as pests, and four of those are primarily found in North American homes. 

Cockroaches are typically small, flat, and oval-shaped. They usually have two antennae and six legs. The following cockroaches have a few distinct characteristics:

Oriental Cockroach

The Oriental Cockroach has a very dark body and can be referred to as “black beetle cockroaches.” Competing with the American Cockroach with its large size, the Oriental Cockroach is typically 1 inch (25 mm) in length. This species is primarily an outdoor cockroach and tends to find its way into homes during the summer months.

German Cockroach

The German Cockroach is roughly ½ to ⅝ inches (13-16 mm) in length, is light brown, and typically has two stripes down its back. Like other common cockroaches, they prefer access to a food and water source and will likely hide in bathrooms or kitchens. They will eat anything in sight and can spread germs as they travel throughout your home.

American Cockroach

The American Cockroach is the largest of the cockroach pests found in homes across North America. Ranging from 1 ¼ to 2 ⅛ inches (32-54 mm), these cockroaches have a reddish tint and are identifiable by the slightly yellow figure eight on top of their head. The American Cockroach is also sometimes referred to as a water bug.

Brown-Banded Cockroach

The Brown-banded Cockroach can be identified by its two light-brown bands found on the back of its primarily brown body. This species is typically ½ inch (13 mm) long and has wings. This roach can be found in furniture and prefers to live in high spaces like cabinets and other elevated areas.  

Will Keeping Lights On Keep Cockroaches Away?

Cockroaches can be found hiding in well-shaded spaces, including small cracks and crevices throughout your home. Light may keep them out of plain sight, but that will not completely prevent or remove them from your home. If a cockroach sees a well-lit area, it will stay in a dark location and may only scurry across that space at night. Interestingly, an experiment performed by Kaitlin A. Dean noted that red light deters cockroaches more than other shades. 

Cockroaches are a nocturnal pest , which means they sleep during the day and are primarily active during the night. Their adaptation to the darkness is a component of their sensitivity to light. A cockroach will prefer to stay hidden, making it challenging to identify a potential infestation in your home if you don’t recognize the warning signs. 

Cockroach Behavior

Cockroaches will multiply quickly and move swiftly throughout an area. They may be hard to identify at first due to their relatively hidden nature. 


Roaches prefer to nest in warm spaces. Behind refrigerators, inside cupboards, underneath furniture, and even dark corners can be an excellent spot for a cockroach nest. Cockroaches shed their skin through a molting process as they enter adulthood. Once the skin sheds, it can be used as part of their nest. You may also find egg cases in the nest as multiple roaches are likely all sharing the same space. 

Travel Habits

Cockroaches are attracted to the scent of other roaches and will travel to the area to live together. If you have multiple cockroaches invading your home, they can and will cover a lot of ground in a short period. A single cockroach can travel up to three miles in one hour. As they scurry across the surfaces in your home, they may also be spreading diseases and harmful bacteria. Even newborn cockroaches can run almost as fast as the mother. 

Laying Eggs

Female cockroaches are pretty powerful when it comes to reproduction. They store male sperm, which allows them to mate once and lay multiple eggs throughout their life. A female will lay a tiny, brown capsule that can contain up to 16 eggs. They will lay anywhere from 6 to 12 capsules in their lifetime. To put that into perspective, a single female could produce 96-192 babies throughout their adult life. 

Once hatched, those eggs will become nymphs and spend the next 6-12 months undergoing maturation and transforming into adults. Part of this transformation includes multiple molting sessions as their bodies increase in size and begin to change. After development is complete, those cockroaches will now mate with other roaches and repeat the process. 

Signs of Cockroaches

Indeed a cockroach sighting is a sure way to know your home has unwanted visitors, but what if these pests never surface during the daytime? A cockroach infestation will have additional signs outside of actually seeing the roaches, such as:

  • A musky odor secreted by the roaches to draw other cockroaches near
  • Egg capsules that are either discarded or waiting to be hatched
  • Moltings that have been left behind during the maturation process
  • Cockroach droppings will look similar to ground coffee
  • Smear marks along walls and other surfaces that cockroaches rub against as they walk
  • Property damage such as chew marks or holes since cockroaches will eat almost anything

How To Prevent Cockroaches in Your Home

Cockroaches need three essential things to live: food, shelter, and water. If you cut off one or all of these sources, you are less likely to find cockroaches living in your home. Be sure to dispose of any food swiftly, refrain from dishes piling in the sink, wiping counters down regularly, keeping pet food or pantry items secure, and regularly clean and vacuum throughout your home. 

Besides keeping the inside of your house clean and well-maintained, outside maintenance can help prevent cockroaches from being attracted to your space. If you have firewood or other debris outside, it needs to be appropriately stored, as well as cleaning any fallen branches or dead plants in your yard. It is also best to keep mulch at least a foot away from your home’s foundation and keep all trash receptacles adequately secured. 

How To Remove Cockroaches

Cockroaches can sustain themselves without food for up to a month. Even if you take away their food and water sources, you may need to take additional steps to exterminate them and resolve the issue entirely. To altogether remove the cockroaches, you will first need to locate and thoroughly dispose of their nest. If you cannot find the nest, consider purchasing a bait such as the Combat Roach Killing Bait that will lure and poison your roaches.

If you have a more significant infestation, you may want to consider hiring a professional exterminator to get the job completely done. These experienced professionals are experts in locating nests and completing removing the issue for you. 

Final Thoughts

Cockroaches are a common pest to many North American households. While they are not attracted to light, they are small enough to still find sneaky hiding spots throughout your home. Since they are so quick to multiply, it is best to promptly remove the roaches as soon as you suspect them before they infest the area.