Fewer than a dozen, but as many as 40 or 50.

Once upon a time, some biologists made a conclusion based on the ecological habits of cockroaches: if there is a global nuclear war on Earth one day, all the creatures in the affected area, including human beings and even fish, will disappear, but only the cockroaches will continue to live their lives.

This is because under normal circumstances, the human body can tolerate the amount of radiation for 5rems, once the total radiation exceeds 800rems, it will die. The German cockroach can tolerate 9000~105000rems, and the American cockroach reaches 967500rem! (denotes the radiation dose. rem dose equivalent Rem (rem) Sie [wot] (Sv) 1Sv=100rem) So even if there is a nuclear explosion, the cockroach can also survive.

The U.S. government spends $1.5 billion a year to exterminate cockroaches, roughly double the budget used to fight AIDS.?

Most of them look alike, but differences can be seen on closer inspection. Current taxonomists categorize cockroaches into about 6,000 species, about 50 of which are pests, such as the common Asian cockroach.

In addition, American cockroaches (American cockroach), German cockroaches (German cockroach), brown cockroaches and Australian cockroaches are also widely distributed. There are about 200 species in China, and there are about 10 species of common indoor cockroaches, which vary from place to place. The common ones are German cockroach, American cockroach and black-breasted cockroach.