The world’s most ubiquitous cockroach — the tiny, tan German cockroach — is currently creeping through countless buildings, hiding in the dark corners of hotel rooms, restaurant kitchens, and, if you’re unlucky, your own home. This tiny little nightmare can squeeze into any crevice, feasting on the crumbs we drop.

Yet, when scientists search for its natural habitat, they come up empty-handed. It turns out that the German cockroach is a bit of an enigma. Despite its name, it’s not native to any wilderness in Germany. In fact, it doesn’t seem to have a wild home anywhere in the world.

“Its origin has been a mystery,” said Edward Vargo, an urban entomologist at Texas A&M University. “These only exist in buildings.”

Now, scientists who conducted a DNA analysis of this cockroach say they have solved the 250-year-old puzzle of where this ubiquitous bug hails from.

The answer is us. Yes, we are responsible for this persistent pest. The species diverged from its closest cousin only about 2,100 years ago — a mere blink in evolutionary time — and has since adapted entirely to living in human dwellings.

“It formed as a species due to its adaptation to human-made environments,” said Vargo, co-author of a study on the cockroach’s origins published in the Proceedings of the National Academy of Sciences. “It’s a creation of human-made environments.”

The German cockroach is a testament to nature’s adaptability, thriving in the most unnatural environments and persisting despite our best efforts to trap, poison, or squash it. This adaptability has allowed it to infest buildings from Alaska to Antarctica, making it one of the world’s most pervasive pests.

How did the German cockroach become so widespread? By hitching rides in cargo on planes, trains, and automobiles. The first records of this pest appeared in Europe in the mid-18th century, shortly after the Seven Years’ War. It likely spread across the continent by hitchhiking with soldiers. Europeans named the new bug after their wartime enemies. Russians called it the “Prussian cockroach,” while some of Russia’s enemies dubbed it the “Russian cockroach.”

Swedish biologist Carl Linnaeus settled on “German cockroach,” and the name stuck. (Sweden fought Prussia in the war.) “The name is truly biased, reflecting the personal or national prejudices of the time,” said Qian Tang, a research associate at Harvard who led the study.

For centuries, the insect’s true origin remained a mystery even as it spread worldwide. It reproduces more quickly than other cockroach species, enhancing its ability to evolve. One key to its success is its resistance to most poisons thrown at it.

“If we can know the origin of the species,” Tang said, “we can try to identify the mechanism of this rapid evolution of insecticide resistance.”

To pinpoint the insect’s inception, Tang and his team collected nearly 300 individual cockroaches from 17 countries on six continents to map its global spread. Their analysis concluded that the species branched off from the Asian cockroach — another invasive species in the U.S. that primarily lives outdoors — after moving in with humans in either India or Myanmar over two millennia ago. From there, German cockroaches hitched rides with travelers during the Islamic dynasties and European colonialism.

Today, the health and economic costs of their spread are significant. Beyond lost business at hotels and restaurants when guests see them scurrying, cockroach infestations can trigger asthma in those allergic to their saliva and feces.

“It’s a big public health concern, especially in low-income housing where treatments for German cockroaches leave much to be desired,” Vargo said.

The study originated from Tang’s doctoral work at the National University of Singapore. Growing up in China, Tang loved watching nature documentaries and reading books about dinosaurs. As a kid, he never imagined his interest in evolutionary biology would lead him to studying a household pest.

“I wasn’t thinking of that,” he said with a chuckle.

Now, researchers aim to identify the genes that have allowed German cockroaches to thrive in urban environments to better manage this pest and others.

“With increasing urbanization, this is just going to become a more common phenomenon,” Vargo said. “The urban environment is becoming a much more prevalent sort of ecosystem.”

As for the name? Tang believes it’s time to drop the German moniker.

“It’s probably necessary to rename it in a more scientific fashion,” he said.

If you’re interested, here’s some more: Two types of cockroaches commonly found in our homes: one American, the other German. Why are they harmful? Where do they lurk?

The German cockroach (Blattella germanica) and the American cockroach (Periplaneta americana) are two distinct species of cockroaches that differ in several key aspects:

Size and Appearance

• German Cockroach: Smaller in size, typically around 1.1 to 1.6 cm (0.4 to 0.6 inches) in length. They are light brown to tan with two dark parallel streaks running from the head to the base of the wings.
• American Cockroach: Significantly larger, averaging 4 cm (1.6 inches) in length but can grow up to 5.4 cm (2.1 inches). They are reddish-brown with a yellowish figure-eight pattern on the back of their heads.

Habitat and Behaviour

• German Cockroach: Prefers warm, humid environments and is commonly found in kitchens, bathrooms, and other indoor spaces. They are highly adapted to living indoors and are often found in human dwellings.
• American Cockroach: Typically found in dark, damp areas such as basements, sewers, and drainage systems. They can live both indoors and outdoors but prefer warmer climates and are often found in commercial buildings.

Reproduction and Lifespan

• German Cockroach: Known for their rapid reproduction, females can produce up to 30-40 eggs per egg case, and the nymphs mature quickly, reaching adulthood in about 100 days. Their lifespan is around 100 to 200 days.
• American Cockroach: Females produce fewer eggs, with about 16 eggs per case, and the development from nymph to adult takes longer, typically around 600 days. They have a longer lifespan, living up to 700 days.

Behaviour and Mobility

• German Cockroach: Less capable of flight and generally prefers to run. They are very agile and can easily hide in small crevices.
• American Cockroach: Capable of gliding flight and often uses its wings to escape threats. They are strong fliers and can move quickly on the ground.

Health and Sanitation

• German Cockroach: Known to carry more pathogens and allergens, posing a significant health risk in residential settings. They can contaminate food and surfaces, contributing to the spread of disease.
• American Cockroach: Also a carrier of pathogens, but less associated with indoor allergen issues compared to the German cockroach. They can spread bacteria and cause contamination in commercial and residential areas.

Control and Prevention

• German Cockroach: Due to their rapid reproduction and preference for indoor environments, they are more challenging to control. Effective management requires persistent efforts including baiting, insecticides, and maintaining high sanitation standards.
• American Cockroach: Control typically focuses on reducing humidity and eliminating access to water sources. They are more likely to be controlled by targeting outdoor habitats and sealing entry points into buildings.

While both species are pests, German cockroaches are smaller, reproduce more rapidly, and are more common in indoor environments, posing significant health risks. American cockroaches are larger, can fly, and are found in both indoor and outdoor environments, with a longer lifespan but slower reproduction rate.

  environment, German Cockroach, insects, pest control