What biologists fear most, of course, is a pest without an enemy, and to obviate this threat, the U.S. spends $ 10 million annually on customs inspection and quarantine.
沒有天敵的昆蟲，是人類最可怕的敵人之一。直到今天，美國每年還要花一千萬美元用在海關檢疫，只怕稍有疏忽，將來得付出幾百倍的代價。