They are small enough to easily slip inside your house, live incolonies that number in the tens of thousands to the hundreds of thousands, and reproduce quickly.
它们很小，可以轻易地溜进你的房子里，成群地生活，数量从几万到几十万，迅速繁殖。
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“Like ants, they gather incolonies, sometimes underground in basements, and work long and hard, ” said Zhou Xiaozheng, a sociology professor at Renmin University in Beijing.
By Mr Chen's calculation, that brings the population of what is possibly the world's rarest bird up to 32, surviving incolonies near some of the densest human populations on earth.