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 .
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 .
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 .
