1. The defoliation of millions of acres of trees by massive infestations of gypsy moth caterpillars is a recurring phenomenon in the northeastern United States. 在美国东北部，舞毒蛾毛虫的大规模侵扰导致数百万英亩的树木落叶，这是一个反复出现的现象。
2. A history of rat infestations in major cities throughout the world. 鼠患的历史在世界各地的主要城市。
3. Their first map focuses on Africa, where worm infestations are worst. 他们的第一批地图着手于非洲，因为那里是寄生虫感染最多的地方。
4. Eosinophils can increase with allergic reactions and with parasitic infestations. 当过敏反应和寄生虫感染时嗜酸性粒细胞会增多。
5. In his captions, letters and journals he complained about dirty streets, insects and rat infestations. 在他撰写的图片解说、信函与日记里，他抱怨街道肮脏、虫鼠成灾。
