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Where Do Cockroaches Come From?

Cockroaches are some of the most common pest insects around the world. These creepy-crawlies are classic symbols of unsanitary conditions in a home. They don’t bite or sting, but they can spread diseases and are a major source of allergens and asthma irritants.

But where do cockroaches actually come from? How do they start an infestation in your home?

This article discusses some of the reasons cockroaches infest our homes and how they get there when they do.

Why Do Cockroach Infestations Happen?

While some pest problems may be caused by insects living in the wild who make their way into our homes, this is less true with cockroaches. While all cockroach species originated in the wild (and there are many left there today), the species that end up in your kitchen live almost exclusively indoors.

The two most common are the German cockroach (Blattella germanica) and the American cockroach (Periplaneta americana).

Despite their names, the cockroaches are native to the tropics, so most tend to die out in the cold. American cockroaches can live in some of the warmer and wetter American states, but German cockroaches are almost never found living outdoors.

Human homes let cockroaches survive in colder climates because they provide everything a roach needs – warmth, moisture, dark places to hide, and decaying organic matter to eat.

Ultimately, cockroach infestations happen because our homes are much more hospitable than nature for these bugs. Cockroaches generally spread from home to home by hitchhiking on objects and people rather than traveling outdoors.

How Do Cockroaches Spread?

Since the most common cockroaches can’t really travel outside, they have some clever strategies for getting from place to place.


Thankfully, cockroaches don’t spend as much time on people as other pests like bed bugs or fleas. However, you may still get cockroaches from your neighbor if you live in an apartment complex or have shared walls with neighboring houses.

Cockroaches can travel through small passageways in the plumbing or gaps in the walls where pipes and electric wires run. This allows them to easily spread to neighboring structures. This is also a big problem for commercial facilities that can spread cockroaches to neighboring businesses.

Boxes from Deliveries

A box shipped from a place with cockroaches may spread the infestation. Boxes are great hiding places for cockroaches as they provide darkness and shelter that they love.

This is especially true for large, industrial shipping since the roaches are less likely to be noticed. However, even a local mail delivery may have a cockroach if the sender has a problem.

A good way to prevent an infestation from coming to you via mail is to immediately dispose of the cardboard boxes away from the home as much as possible and look around the edges and flaps of the boxes upon opening them.

Grocery Bags

Pests love grocery stores since they are major sources of warmth, moisture, and food. While grocery stores work very hard to keep cockroaches away, cockroaches may occasionally make it home through a grocery bag.

This can be especially convenient for cockroaches since they most often infest kitchens where they’ll find both food and water.

Check your groceries on the way in, especially if you have paper bags where they’ll be harder to spot and more likely to be. Dispose of your grocery bags away from the home whenever possible.


Cockroaches may also come home with workers or students. Luckily, they are usually too large to travel directly on a person’s skin without being noticed, but they can easily end up in bags, backpacks, or even clothing that has been left on the floor.

If you see cockroaches at your school or place of work or are aware of a recent infestation, be vigilant about inspecting anything you bring back and forth between home and the office.


Many sewers are full of cockroaches. If they stay in the sewer, they don’t always pose a major problem (though they can be unpleasant for sewer workers).

However, sewer roaches can end up in homes as well. When sewage systems are repaired, the displaced roaches can back up into people’s homes or into commercial facilities. Roaches can enter the sewers from these buildings as well.

Used Appliances

If the previous owner had a roach infestation, there are probably roaches hiding in used appliances like ovens, microwaves, dishwashers, and toaster ovens.

The warmer and wetter the appliance – the more likely it is to be comfortable for roaches.  Check appliances carefully before bringing anything into your home.

Final Thoughts

Sometimes a roach infestation is all but unpreventable. If a sewage repair backs up roaches into your home, there’s not much you could have done to prevent that.

But some of the ways that roaches travel into your home are very preventable. If you live in a major city, you should always carefully inspect any delivery or appliance you bring into your home. Check your bags and lunch containers, as well as any food you bring home from the grocery store. And make your home as uncomfortable for roaches as possible by keeping it clean, ventilated, and dry.

So while you may not be able to prevent every infestation, you can certainly give yourself a fighting chance.

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Written by Miles Martin

Miles is a professional science writer with a Bachelor of Arts in Biology from the University of Rhode Island and a Masters of Science in Science Communication and Public Engagement from the University of Edinburgh.

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