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Ever used an exterminator to get rid of mice , termites , fleas or cockroaches ?

曾经用药除过老鼠，白蚁，跳蚤和蟑螂吗？

A study last year in the american journal of tropical medicine and hygiene suggested that early snowmelt in western states had led to drier soil in rodent burrows and fewer fleas to spread plague .

美国热带医学及卫生杂志去年的一份研究表明，美国西部地区积雪提早融化使得啮齿动物洞穴的土壤更加干燥，跳蚤传染的瘟疫爆发少了。

As you watch them jump and hit the top , you will notice something interesting . The fleas continue to jump , but they are no longer jumping high enough to hit the top .

当你观察它们跳跃并且撞到盖子的时候，你会发现一件有趣的事情，跳蚤会继续跳，但是它们不再跳到能撞到盖子的那个高度。

Planes sprayed the zone with a plague culture or dropped bombs with plague-infested fleas to see how many people would die .

飞机在此区域撒播瘟疫培养菌或投下装有感染瘟疫的跳蚤的炸弹，以观察有多少人会死亡。

Newly found fossils of fleas , 165 million years old , show that the critters were almost an inch in length and had blood-sucking mouthpieces that scientists say were used to penetrate tough hides .

从这一新发现的1.65亿年前的跳蚤的化石可以看出，这种小生物几乎有一尺长并且还有吸血用的吸嘴，科学家说那是用来穿透坚韧厚实的毛皮的。