Is the North about to fall? The big, flying southern cockroaches are coming in droves!

Audit expert: Mo Jianchu

Professor, Institute of Insect Science, College of Agriculture and Biotechnology, Zhejiang University

There is a kind of insect: it has a flat body, long antennae, it crawls around in the house, and it can even fly!

It is a solitary "bug" that can make a group of netizens lose their ability to control their expressions without making any noise, and can "win the enemy without fighting."

Do you know who we are talking about? That’s right, cockroaches .

Source: pixabay

Do you have the urge to pick up your slippers in front of the screen?

Cockroaches are also called "invincible cockroaches". Are cockroaches really invincible?

In fact, a cockroach can be easily killed. Just muster up your courage, raise your slippers, aim and shoot. But this cannot completely solve the problem of the rampant cockroach family in your home. Strictly speaking, cockroaches are not undying, but they can never be completely killed.

1Why can’t we kill all the cockroaches?

Cockroaches have strong adaptability to the environment

Cockroaches like to live in warm, humid, food-rich and crevices-filled places. Sewers, express boxes, under bookshelves, corners and other hidden corners are all cockroaches' "base camps".

Cockroaches can live in groups

The image of swarms of cockroaches crammed into a small space gives many people a chill just thinking about it. Cockroaches can live together in extremely high densities and will not kill each other as long as there is enough food.

Cockroaches have a strong reproductive capacity: they lay a lot of eggs in a short period of time.

Cockroaches reproduce very quickly. A mature female German cockroach can produce an ootheca containing 14 to 40 eggs every 7 to 10 days, and can produce nearly 10,000 offspring a year, up to 100,000. Even in extreme conditions where there are no male cockroaches, female cockroaches can lay eggs. That is, the same female cockroach only needs to mate once to store sperm and lay eggs continuously.

The most terrifying thing is that dead German cockroaches can still lay eggs! It sounds incredible, but it is true. The eggs of German cockroaches are located in the relatively safe egg sheath at the tail. The mother and the egg sheath exist independently. If the mother dies but the egg sheath is not destroyed, the cockroaches will still hatch.

However, the American cockroach, the black-breasted cockroach and other cockroaches do not have this characteristic. This is because the eggs of the German cockroach rely on the mother to provide the required humidity for hatching, while the hatching of cockroach eggs relies on the environment to provide the required humidity. Generally, the humidity required for the hatching of cockroach eggs is above 70%.

Therefore, the German cockroach can live and survive in a dry indoor environment, while the Periplaneta is only suitable for breeding in relatively humid environments, such as sewers, and then invade indoor areas through other pipes.

Source: pexels

2. There are also differences between cockroaches in the north and south

Southern cockroaches are generally huge in size, love to visit other people's homes, and like to catch humans off guard; northern cockroaches seem to be much friendlier, smaller in size, and prefer to stay in dry places indoors, living in "harmony" with humans.

More than a decade ago, compared to southern netizens' deep hatred for cockroaches, northern netizens' impression of cockroaches was probably still vague. Even if they saw them, they rarely made a fuss, thinking it was nothing more than a slipper.

Source: The Paper

But in recent years, the "southern cockroaches migrate to the north" situation is not uncommon. Many northern netizens have also found large cockroaches at home. After asking online, they found out that these are the legendary southern giant cockroaches. Could it be that southern cockroaches have migrated to the north?

Previously, a Shandong netizen recorded the moment his defense was broken on Weibo. Giant southern cockroaches suddenly appeared in his home. According to professionals, the invader was an Australian cockroach, which had already begun to march northward.

Source: Weibo screenshot

3Is the southern cockroach’s hometown in the south?

Cockroaches are insects of the Blattaria family. There are many species, with more than 5,000 known species worldwide. Most of them live in the wild and will not visit human residences. The main indoor "rampant" ones in my country are the German cockroach, Australian cockroach, American cockroach, and black-breasted cockroach.

Common cockroaches in the home: A: German cockroach (German cockroach) B: American cockroach (American cockroach) C: Australian cockroach (Australian cockroach) D and E: Female and male Oriental cockroach Source: Wikipedia

The southern part of my country has sufficient rainfall, a warm and humid climate, and most houses are made of brick and wood, which provides an environmental foundation for the reproduction of cockroaches and is more suitable for the survival of large cockroaches.

Most of the cockroaches that are rampant in the south, creating a huge visual impact and causing humans to fight wits and courage for centuries are American cockroaches . Other species include black-breasted cockroaches, Australian cockroaches, brown-spotted cockroaches and Japanese cockroaches. Cockroaches have now become pests distributed worldwide.

American cockroach Source: Wikipedia/Jan Drewes

Although the American cockroach has America in its name, it is actually native to Africa and the Middle East and was introduced to America in the 2nd century AD. Therefore, although these cockroaches have become a "specialty" in the south, they are actually still "outsiders."

As for the north, under the influence of the cold and dry climate, cockroaches are mostly small in size, only one-third or one-fourth the size of those in the south. They are more agile and convenient to move. Most of them are German cockroaches.

In the cold winter, German cockroaches can use their petite body to easily get into extremely small places such as radiators, inside range hoods, and refrigerator heat sinks. This is an ability that southern cockroaches do not have, which gives them an advantage in resisting the cold winter and dominating the area.

4Why did cockroaches from the south move north?

For some time, southern cockroaches have appeared frequently in the north, shocking northern netizens who "don't know how to identify cockroaches" and have been frightened wave after wave by these southern specialties that have come from afar.

Why do cockroaches in the south leave their warm and humid hotbeds and travel long distances to suffer in the dry north? Can they adapt to the completely different climate?

Global warming

As the global climate warms, the climate in the north is gradually becoming adaptable to southern cockroaches, so the distribution range of southern cockroaches is gradually moving northward.

In addition, in the north, there is heating indoors in winter, and the temperature is relatively suitable. In places such as kitchens, there are moist floors or drainage pipes, which have the humidity required for the survival of cockroaches. Therefore, if a small number of cockroaches spread to the north through various channels, they will naturally reproduce in the case of abundant food.

The rapid development of logistics

The southern cockroaches did not appear suddenly in the north, but were transported to the north by express delivery. Netizens in the south must have seen cockroaches in the express boxes piled in the corner. The cockroaches crawled in through the gaps in the boxes and used this place as a new "base" to reproduce.

At the express delivery stations along the way, cockroaches enter the express packages through the gaps in the poorly sealed cartons, and travel a long distance from the south to a new world along the logistics chain.

Source: The Paper

Now, it is an indisputable fact that cockroaches from the south have moved north. But netizens in the north don't need to be too nervous, as the ability of southern cockroaches to survive in the north is still relatively limited. It is recommended that you carefully clean the small gaps in your home, the piles of cardboard boxes and sundries, and the spotlights, so as not to provide a suitable residence for cockroaches to invade.

If they are not indoors, most cockroaches that come from the south cannot withstand the cold winter in the north.

If cockroaches have already appeared in your home, you can use cockroach sticky boards or insecticides, but you must buy qualified products that are harmless to humans and the environment before you can use them with confidence. In addition, if cockroaches are rampant in your home, you can hire a professional pest control company to eliminate them comprehensively, leaving no cockroach behind.