Written by

David Floyd

David Floyd

Reviewed by

Brett Ehlert

Brett Ehlert

Why Do Cockroaches Come Out At Night?

why do cockroaches come out at night

Cockroaches are a common sight in kitchens at night, but not as frequently during the day. This raises the question: why do cockroaches prefer to come out at night?

There are 4,000 to 4,600 estimated species of the vermin, with 36 of them living in human habitat and 4 being pests, so when we refer to roaches in an everyday context, we’re talking about one or all of the following:

  • German cockroaches
  • American cockroaches 
  • Oriental cockroaches
  • Brown-banded cockroaches

Why Do Roaches Come Out At Night?

Now you might be wondering: Why do cockroaches come out at night? Are cockroaches nocturnal? 

The answer to both questions is: Yes, cockroaches come out at night because they are nocturnal animals.

A nocturnal animal is an animal that is active during the night but sleeps during the day. The reason for this is due to their circadian rhythm. Every living creature has a circadian rhythm or system. This means changes that happen in the body within 24 hours. It is a mental clock that oversees sleeping and waking (alertness and dizziness) thereby making an organism most ready for functioning well. It works with light and dark.

The sleep-wake cycle is the master circadian rhythm, but other types regulated by it are hormonal, eating and digesting, and body temperature. There are two broad sleep circles:

  • Diurnal
  • Nocturnal

Diurnal circadian rhythm is a bodily function of activity and inactivity matching sunrise and sunset seemingly naturally. Diurnal animals, such as humans and butterflies, are up and about during the day but sleeping or resting when it is night. The nocturnal circadian system on the other hand works oppositely. Waking, and activities for nocturnal animals are controlled by the dark, and rest or sleep by daylight. Insects such as roaches and moths fall in this category.

Read our guide on how to keep roaches away at night!

Why Are Roaches Nocturnal?

Roaches need no introduction. They are pests – irritating, damaging, persistent insects – and can cause an unsettling feeling when they are spotted in the least expected places. This gets worse at night because one has little to no control over the situation unlike in the daytime when they can be clearly seen and perhaps killed. Read our guide on getting rid of roaches in your home.

Roaches aren’t necessarily nocturnal; they have rather evolved to being one. They are one of the most adaptable animals after all. So, although, they are generally nocturnal, they can be seen during the day. One reason for this could be an infestation in the home. They hide in cracks, crevices, and small spaces but when these places are filled with roaches, the rest of them are forced to come out.

Cockroaches are also drawn to relatively humid or warm environments. This explains why you tend to find them in drainages and sewers in the home or right in front of TV screens and flying around light bulbs (for their warmness). Harsh or artificial lighting, on the other hand, is a no-go area for them. Natural lighting for them has come to be associated with the presence of a predator. They are easier to shake out and kill during the day, and most people tend to flip on the light switch when they hear a ruffling/buzzing sound or sense a “crawly” feel on their skin.

Can Roaches See In the Dark?

Roaches can see in the dark because of their adaptive ability as was mentioned earlier. Just like other nocturnal animals, they possess developed and good senses of sight, smell, and hearing to make up for the lack of daylight they avoid and the limited one of the night they make do with. They have photoreceptors in their large compound eyes which enables them to see different things at the same time.

Their antennae – thin, long, threadlike pairs attached to their heads also help them in feeling their way around. They use it to smell and search for food, as well as sense danger and detect vibrations (when a human is nearby, for instance).

Do Roaches Sleep? How?

Roaches usually come out when it is four hours after the last light of the day has gone out. They follow a daily circle of three stages, as researched by Professor Irene Tobler-Borbly:

  • The first stage is the locomotion stage. This is the time when they are active and everywhere looking for leftover food or seeking a mate, etc.
  • The second stage is known as a limb or antennal movement. It could also be seen as somewhat partial immobility because the cockroach at this stage is not mobile, but its legs and antennae are still moving.
  • The final and last stage is the immobility stage and it is where the roach goes into a deep rest or “semi-sleep.” It is simply completely still but not unconscious and it lasts for about 8 hours before the circle repeats itself.

The rest just by staying in a calm, steady spot and state, and in their favorite places – where they love to hide. Holes, slits, debris, sewage and drainage, drawers and shelves, behind wallpapers and underneath mats, containers, in between folds of clothes, and in other misty, dark places.

Some Facts About Cockroaches

We’ve been looking at the sleep and basic routine of these critters and they all seem basic at most, but this is not all there is to the creatures usually 1.5 inches to 3.5 inches long. There are more amazing facts about them and we’ll look at a few below:

Roaches can run for about 3 miles in an hour:

And cover the length of 50 bodies in a second. All thanks to their legs, three on either side of their body, making a total of six. Each leg also has three knees, numbering 18 altogether. The hind or back leg (metathoracic) is the one responsible for the roach taking off, and it alone could be enough for a roach’s flight. The other legs are the front (prothoracic) and middle (mesothoracic) legs, and they as serve as break and speed control respectively. 

Cockroaches can survive without their heads for a week:

This is because they have tiny holes called “spiracles” all over their bodies, and this is what they breathe through. The antennae on the head also continue to move for a while even after the head has been cut off.

They are cold-blooded:

This means that they generate little or no internal heat or body temperature. Rather they try to adapt to their environment, depending on these places and their atmospheres to either keep themselves warm or cold. The rate at which they break down food (metabolism) into energy they can use is also very low, and because of their long rest periods, they end up saving this energy which in turn prolongs their lives.

They can live without food for a month:

This is for the same reason they are cold-blooded. Since they store up a lot of their energy, they can spread its use out to sustain themselves in times when they find no food.

Roaches can go without water for a week:

Water, unlike food for them, is a necessity, and because they do not have anywhere to conserve water in their makeup, they can only make do with a lack of it for about a week.

They are omnivorous:

Roaches feed on anything – from humans to plants and dead animals, and even inanimate things (glue, paper, hair, etc).

More Facts

  • A day-old roach can run just as fast as its parents.
  • German cockroaches take as little as 36 days to mature into adulthood.
  • They can stay underwater for up to an hour.
  • They can hold their breaths for more than thirty minutes.
  • Roaches can regrow their limbs.
  • They have exoskeletons (molts) which they shed off many times in their lives.
  • Female roaches are oviparous:
  • They carry their young ones in a bean-like sac known as ootheca (an egg).
  • There are always traces of chemicals in their feces, which they leave as a trail for other roaches to follow in finding food.
  • They have short, sticky protrusions on their legs which make it possible for them to cling to vertical surfaces such as walls, etc., or ceilings.
  • They are always born white but go on to get their dark-brown coloring as they age. The hormone responsible for the change is the bursicon.
  • The largest cockroach in the world is six inches long and it is only found in South America.

Final Thoughts On Why Cockroaches Come Out At Night

Cockroaches come out at night because they are nocturnal animals. A nocturnal animal is one that is active at night but sleeps during the day. The reason for this is because of their circadian rhythm. Have you got roaches and pests in your house but don’t know what to do to get rid of them? Reach out to a pest control professional today for help. 

Thank you for reading my guide on why do cockroaches come out at night.



David Floyd:

David Floyd has 20 years of experience working as a pest control technician as well as running his own pest control company. David is Quality Pro certified and is a certified Structural Pest Control Operator in the state of North Carolina, and the owner of NCPestControlExperts pest control company.

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