The culprit is methyl parathion, which has been used to combat pests like the boll weevil, scourge of the cotton fields.
That failed in 1961as did methyl parathion in 1963, and fenthion in 1968.
Meanwhile, the insecticide barrage had been augmented by dieldrin, parathion, heptachlor, malathion and other fearful compounds many times stronger than DDT, all of which the .