Abnormal occurrence

…It refers to the phenomenon in which a certain organism, especially an animal, suddenly increases the population compared to normal. It is also called an abnormal outbreak. There are two main types of outbreaks. One is a sudden increase in population in only one generation, which is called a sudden outbreak. …

*Some of the terminology used to refer to "abnormal occurrence" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ある生物とくに動物が通常に比べ急に大幅な個体数の増加を引き起こす現象を指す。異常発生とも呼ばれる。大発生には大きく分けて二つの型があり，一つは一世代だけで急激な個体数増加を示すもので突発的大発生sudden outbreakと呼ばれる。…

※「異常発生」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報