The good news is that in the fight against malaria we have a weapon that is cheap, easy to use, and highly effective. Widely used as an agricultural pesticide after World War II, DDT eventually came to be seen as an insidious agent of ecological destruction. The United States outlawed it in 1972 because of evidence it was helping wipe out the peregrine falcon, the bald eagle and other birds. Using this pesticide may sound like a terrible idea to anyone who remembers it as the surest way to put a species on the endangered list. But in the bad old days, DDT was sprayed in huge volumes on entire fields of crops to kill insects.
Nobody proposes to do that today.
What public health experts endorse is spraying small amounts on the indoor walls of homes in malarial zones. You can treat the homes in an entire tropical country with the amount of DDT that once would have been used on a single farm. Does it ever. Since mosquitoes are most active at night, when people are indoors, DDT sharply reduces the transmission of malaria. During the 1990s, countries like Brazil and Peru stopped using the stuff and saw their malaria rates soar.