Used primarily as an insecticide in agricultural and public health programs to control mosquitoes, flies, and other disease-carrying insects. Its effectiveness in reducing malaria and typhus transmission made it widely used in the mid-20th century, especially in tropical and subtropical regions. Applied in indoor residual spraying to kill insects that rest on walls after feeding. Also used in some cases for crop protection against soil-dwelling pests. Due to environmental persistence and toxicity to non-target species, its use is now restricted or banned in many countries, though limited applications are still permitted in specific vector control programs under strict regulation.