Original sentence: DDT was initially extremely effective, but U.While many control methods have been investigated since the boll weevil entered the United States, insecticides have always remained the main control methods.weevil populations developed resistance by the mid-1950s
Edited sentence: DDT was initially extremely effective, but US weevil populations developed resistance by the mid-1950s.While many control methods have been investigated since the boll weevil entered this country, insecticides have always remained the main control methods